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#1
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One for the electrical boys, please ...
We are in the process of taking some modern commercial premises, in which
the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Help please, lads ... !! d:-) TIA Arfa |
#2
Posted to uk.d-i-y
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One for the electrical boys, please ...
"Arfa Daily" wrote in message ... We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Just a query in passing - IIUC you can get industrial machinery (such as lathes, drills etc.) which run on 3 phase directly - which would obviously require three phases. If you have normal 230V kit do you have two supplies of 230V split between the three phases when you install a 3 phase supply? Cheers Dave R |
#3
Posted to uk.d-i-y
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One for the electrical boys, please ...
On 13/04/2011 19:00, David WE Roberts wrote:
Just a query in passing - IIUC you can get industrial machinery (such as lathes, drills etc.) which run on 3 phase directly - which would obviously require three phases. If you have normal 230V kit do you have two supplies of 230V split between the three phases when you install a 3 phase supply? Cheers Dave R No, a 3-phase supply will come as 4 wires: L1, L2, L3 and N. Each phase ( L1, L2, L3 ) to N is a standard 240v supply. Phase-to-Phase is 415v. ( Give or take the EU harmonisation voltages etc.. ) So you can feed 3-phase motors etc off L1, L2, L3. They typically won't require the N. The dist board will have a 3-phase incomer, and 3 L bus-bars. 3-pole breakers will connect to each of the L to feed 3-ph loads. Single-pole MCBs will connect to only one L, and the single-phase wiring will then use the N bar, just like a domestic CU. -- Ron |
#4
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One for the electrical boys, please ...
Arfa Daily wrote:
We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Have you got 3 phase appliances? It is worth noting that 3x100A fuses on a 3 phase supply does not give you 300A of available power for 230V appliances (no matter how well you share the load between the fuses) as the neutral is only rated at 100A. I have not done 3 phase for a while (other than just connect up a few machines) but 40kVA sounds like he has just multiplied 400 (the nominal voltage between phases) by the 100A fuse. ISTR that it should be multiplied by sq rt of 3 to get the maximum power. With a bit of (bad) luck Dennis should be along shortly to explain everything as he is a f***ing know all. -- Cheers Adam |
#5
Posted to uk.d-i-y
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One for the electrical boys, please ...
On Apr 13, 7:37*pm, "ARWadsworth"
wrote: Arfa Daily wrote: We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? *I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Have you got 3 phase appliances? It is worth noting that 3x100A fuses on a 3 phase supply does not give you 300A of available power for 230V appliances (no matter how well you share the load between the fuses) as the neutral is only rated at 100A. I have not done 3 phase for a while (other than just connect up a few machines) but 40kVA sounds like he has just multiplied 400 (the nominal voltage between phases) by the 100A fuse. ISTR that it should be multiplied by sq rt of 3 to get the maximum power. With a bit of (bad) luck Dennis should be along shortly to explain everything as he is a f***ing know all. -- Cheers Adam- Hide quoted text - - Show quoted text - If each phase was taking 100Amps there would be no neutral current at all. A neutral current only appears when the phase currents are unbalanced. |
#6
Posted to uk.d-i-y
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One for the electrical boys, please ...
harry wrote:
On Apr 13, 7:37 pm, "ARWadsworth" wrote: Arfa Daily wrote: We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Have you got 3 phase appliances? It is worth noting that 3x100A fuses on a 3 phase supply does not give you 300A of available power for 230V appliances (no matter how well you share the load between the fuses) as the neutral is only rated at 100A. I have not done 3 phase for a while (other than just connect up a few machines) but 40kVA sounds like he has just multiplied 400 (the nominal voltage between phases) by the 100A fuse. ISTR that it should be multiplied by sq rt of 3 to get the maximum power. With a bit of (bad) luck Dennis should be along shortly to explain everything as he is a f***ing know all. -- Cheers Adam- Hide quoted text - - Show quoted text - If each phase was taking 100Amps there would be no neutral current at all. A neutral current only appears when the phase currents are unbalanced. Not if the OP is only using 230V appliances. Please pay attention to what is written. -- Adam |
#7
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One for the electrical boys, please ...
-- Cheers Adam- Hide quoted text - - Show quoted text - If each phase was taking 100Amps there would be no neutral current at all. A neutral current only appears when the phase currents are unbalanced. Not if the OP is only using 230V appliances. Please pay attention to what is written. -- Adam I really hesitate to differ, but are you saying that, if each 230 V appliance was taking 100A, there would be 300A in the neutral? |
#8
Posted to uk.d-i-y
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One for the electrical boys, please ...
newshound wrote:
-- Cheers Adam- Hide quoted text - - Show quoted text - If each phase was taking 100Amps there would be no neutral current at all. A neutral current only appears when the phase currents are unbalanced. Not if the OP is only using 230V appliances. Please pay attention to what is written. -- Adam I really hesitate to differ, but are you saying that, if each 230 V appliance was taking 100A, there would be 300A in the neutral? No there would not be 300A in the neutral. -- Adam |
#9
Posted to uk.d-i-y
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One for the electrical boys, please ...
newshound wrote:
-- Cheers Adam- Hide quoted text - - Show quoted text - If each phase was taking 100Amps there would be no neutral current at all. A neutral current only appears when the phase currents are unbalanced. Not if the OP is only using 230V appliances. Please pay attention to what is written. -- Adam I really hesitate to differ, but are you saying that, if each 230 V appliance was taking 100A, there would be 300A in the neutral? I calculate it that if you have all three phases drawing 100A, the neutral would be carrying only stray currents, but if only one phase was loaded, the neutral current would be equal to the load current. With two running, it's something on the order of 1/ (square root of 2) multiplied by the combined load current, so in this case about 141A maximum with full load on two phases. With three phases running in balance, it's close to zero. It's a vector sum, and the worst case is with two phases running at full load, and the other one drawing zero load. For other combinations, it depends on the loads on each phase. -- Tciao for Now! John. |
#10
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One for the electrical boys, please ...
"ARWadsworth" wrote in message ... Not if the OP is only using 230V appliances. Please pay attention to what is written. Do pay attention, he has two 9 kW fryers, they are not going to be 230V. Even the dishwasher I put in was three phase and that was only 7 kW. And no I don't know enough about 3 phase to answer the OPs questions. |
#11
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One for the electrical boys, please ...
In article , dennis@home
writes Do pay attention No thanks. re-plonked due to morph. -- (\__/) (='.'=) (")_(") |
#12
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One for the electrical boys, please ...
On 13/04/2011 21:15, dennis@home wrote:
"ARWadsworth" wrote in message ... Not if the OP is only using 230V appliances. Please pay attention to what is written. Do pay attention, he has two 9 kW fryers, they are not going to be 230V. Even the dishwasher I put in was three phase and that was only 7 kW. And no I don't know enough about 3 phase to answer the OPs questions. Is that 9kW including VAT or plus VAT? -- Dave - The Medway Handyman www.medwayhandyman.co.uk |
#13
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One for the electrical boys, please ...
In message , "dennis@home"
writes "ARWadsworth" wrote in message ... Not if the OP is only using 230V appliances. Please pay attention to what is written. Do pay attention, he has two 9 kW fryers, they are not going to be 230V. Even the dishwasher I put in was three phase and that was only 7 kW. And no I don't know enough about 3 phase to answer the OPs questions. FFS pay attention There will be two electrical fryers, each loading at 2 x 9kW, -- hugh "Believe nothing. No matter where you read it, Or who said it, Even if I have said it, Unless it agrees with your own reason And your own common sense." Buddha |
#14
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One for the electrical boys, please ...
On Apr 13, 7:59*pm, "ARWadsworth"
wrote: harry wrote: On Apr 13, 7:37 pm, "ARWadsworth" wrote: Arfa Daily wrote: We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Have you got 3 phase appliances? It is worth noting that 3x100A fuses on a 3 phase supply does not give you 300A of available power for 230V appliances (no matter how well you share the load between the fuses) as the neutral is only rated at 100A. I have not done 3 phase for a while (other than just connect up a few machines) but 40kVA sounds like he has just multiplied 400 (the nominal voltage between phases) by the 100A fuse. ISTR that it should be multiplied by sq rt of 3 to get the maximum power. With a bit of (bad) luck Dennis should be along shortly to explain everything as he is a f***ing know all. -- Cheers Adam- Hide quoted text - - Show quoted text - If each phase was taking 100Amps there would be no neutral current at all. A neutral current only appears when the phase currents are unbalanced. Not if the OP is only using 230V appliances. Please pay attention to what is written. -- Adam- Hide quoted text - - Show quoted text - It matters not If all were using the same Kw, Where the separate neutral wires meet, the sum is zero. |
#15
Posted to uk.d-i-y
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One for the electrical boys, please ...
In message , ARWadsworth
writes Arfa Daily wrote: We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Have you got 3 phase appliances? It is worth noting that 3x100A fuses on a 3 phase supply does not give you 300A of available power for 230V appliances (no matter how well you share the load between the fuses) as the neutral is only rated at 100A. I have not done 3 phase for a while (other than just connect up a few machines) but 40kVA sounds like he has just multiplied 400 (the nominal voltage between phases) by the 100A fuse. ISTR that it should be multiplied by sq rt of 3 to get the maximum power. With a bit of (bad) luck Dennis should be along shortly to explain everything as he is a f***ing know all. You forgot Harry ... -- geoff |
#16
Posted to uk.d-i-y
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One for the electrical boys, please ...
geoff wrote:
In message , ARWadsworth writes Arfa Daily wrote: We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Have you got 3 phase appliances? It is worth noting that 3x100A fuses on a 3 phase supply does not give you 300A of available power for 230V appliances (no matter how well you share the load between the fuses) as the neutral is only rated at 100A. I have not done 3 phase for a while (other than just connect up a few machines) but 40kVA sounds like he has just multiplied 400 (the nominal voltage between phases) by the 100A fuse. ISTR that it should be multiplied by sq rt of 3 to get the maximum power. With a bit of (bad) luck Dennis should be along shortly to explain everything as he is a f***ing know all. You forgot Harry ... No, I didn't. And I was wrong. I offered my apologies to Harry. What more can you do? I was wrong and I admitted it. I will not try to make excuses, I will eat humble pie. -- Adam |
#17
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One for the electrical boys, please ...
On Apr 13, 10:36*pm, "ARWadsworth"
wrote: geoff wrote: In message , ARWadsworth writes Arfa Daily wrote: We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? *I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Have you got 3 phase appliances? It is worth noting that 3x100A fuses on a 3 phase supply does not give you 300A of available power for 230V appliances (no matter how well you share the load between the fuses) as the neutral is only rated at 100A. I have not done 3 phase for a while (other than just connect up a few machines) but 40kVA sounds like he has just multiplied 400 (the nominal voltage between phases) by the 100A fuse. ISTR that it should be multiplied by sq rt of 3 to get the maximum power. With a bit of (bad) luck Dennis should be along shortly to explain everything as he is a f***ing know all. You forgot Harry ... No, I didn't. And I was wrong. I offered my apologies to Harry. What more can you do? I was wrong and I admitted it. I will not try to make excuses, I will eat humble pie. -- Adam- Hide quoted text - - Show quoted text - We all still love you :-) |
#18
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One for the electrical boys, please ...
On 14/04/2011 16:05, harry wrote:
On Apr 13, 10:36 pm, wrote: wrote: In , ARWadsworth writes Arfa wrote: We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Have you got 3 phase appliances? It is worth noting that 3x100A fuses on a 3 phase supply does not give you 300A of available power for 230V appliances (no matter how well you share the load between the fuses) as the neutral is only rated at 100A. I have not done 3 phase for a while (other than just connect up a few machines) but 40kVA sounds like he has just multiplied 400 (the nominal voltage between phases) by the 100A fuse. ISTR that it should be multiplied by sq rt of 3 to get the maximum power. With a bit of (bad) luck Dennis should be along shortly to explain everything as he is a f***ing know all. You forgot Harry ... No, I didn't. And I was wrong. I offered my apologies to Harry. What more can you do? I was wrong and I admitted it. I will not try to make excuses, I will eat humble pie. -- Adam- Hide quoted text - - Show quoted text - We all still love you :-) But only in a manly, viking way.... -- Dave - The Medway Handyman www.medwayhandyman.co.uk |
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One for the electrical boys, please ...
On Apr 13, 5:20*pm, "Arfa Daily" wrote:
We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". I have not the slightest idea what the difference between these is, or which it will be that we need ?? *I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main.. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Help please, lads ... !! * * *d:-) TIA Arfa Whole current means the meters pass the whole current through them (as you might think). CT=current transformer. For large industrial supplies. The current passes through a Current Transormer which reduces the cureent to usually 5amp max, There are different ratios on the CT eg 50:1 would be a 250 amp supply. 100:1 would be a 500amp supply. etc. I should think each flat would be given a single phase supply, 100a is ample. You will be "whole current" |
#20
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One for the electrical boys, please ...
On 13/04/2011 17:20, Arfa Daily wrote:
snip Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. /snip Find the specs for that aircon unit. I'd expect it to use a substantial fraction of the heat it needs to get rid of - and on a hot summer's day that will be the whole 36kW and a bit. I'm no expert (I merely suffer these things in computer rooms) but I wouldn't be at all surprised to find it eats another 18kW. Seems to me that may exceed your power limit. Splitting this lot evenly over three phases isn't going to be possible. Some of the time you'll have load on one of the phases only, sometimes two, and only occasionally all three. Andy. |
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One for the electrical boys, please ...
On Apr 13, 9:21*pm, Andy Champ wrote:
On 13/04/2011 17:20, Arfa Daily wrote: snip Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. /snip Find the specs for that aircon unit. *I'd expect it to use a substantial fraction of the heat it needs to get rid of - and on a hot summer's day that will be the whole 36kW and a bit. *I'm no expert (I merely suffer these things in computer rooms) but I wouldn't be at all surprised to find it eats another 18kW. Seems to me that may exceed your power limit. Splitting this lot evenly over three phases isn't going to be possible. * Some of the time you'll have load on one of the phases only, sometimes two, and only occasionally all three. Andy. It depends on the Coefficient Of Performance of the AC system. Typically three. (Varies with outside air temperature.) So.that's about 11 Kw split between three phases, equals 3.6Kw/phase is about 15 amps per phase. More or less. |
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One for the electrical boys, please ...
On Apr 13, 5:20*pm, "Arfa Daily" wrote:
We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Help please, lads ... !! * * *d:-) TIA Arfa 40 Kva is approx 53 amps/phase,so he is trying to split the available power equally between the two units. At that level you want the "whole current" and 415v options. |
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One for the electrical boys, please ...
"mark" wrote in message ... On Apr 13, 5:20 pm, "Arfa Daily" wrote: We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? Help please, lads ... !! d:-) TIA Arfa 40 Kva is approx 53 amps/phase,so he is trying to split the available power equally between the two units. At that level you want the "whole current" and 415v options. OK. Thanks for all the useful information, everyone. Looks like I need to do a bit more research. I just went looking at the detailed specs for the proposed fryers, and interestingly, it states neither a supply voltage nor a phase requirement. Only that it is 2 x 9kW. I must admit that I never even considered that they might be three phase. I have now shot an email off to the manufacturers to enquire on this point. However, when I was reading up on them, it seems to me that the proposed model has way more capacity than we are going to require. My daughter has specced all of the equipment, and I'm not sure quite how she arrived at this model. I will ask her tomorrow, as from what I can see, the manufacturer has models of much more modest power requirements, that would easily be able to keep up with the demand that's going to be placed on them. Arfa |
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One for the electrical boys, please ...
In article , Arfa Daily
writes from what I can see, the manufacturer has models of much more modest power requirements, that would easily be able to keep up with the demand that's going to be placed on them. If the 9kW model your daughter has (over)specced is single-phase, rather than install two of those, you might be able to settle on three smaller single-phase models, one on each phase, to help with load balancing. -- (\__/) (='.'=) (")_(") |
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One for the electrical boys, please ...
"Mike Tomlinson" wrote in message news In article , Arfa Daily writes from what I can see, the manufacturer has models of much more modest power requirements, that would easily be able to keep up with the demand that's going to be placed on them. If the 9kW model your daughter has (over)specced is single-phase, rather than install two of those, you might be able to settle on three smaller single-phase models, one on each phase, to help with load balancing. I would love to see the maths on that.. three fryers all operating their own heating cycle, based on when you switched them on, how much and what type of food you put in, etc. They could end up in phase or out of phase with each other for unknown periods of time as they cycle. An electricians nightmare IMO, but that's diversity for you. I would just ensure they were three phase so all the heaters were on at the same time whatever you put in them. Being as I can cook a bit I can also understand why she would want a high power input too, you don't want it to keep going cold every time you chuck some food in. You want a fast recovery time to ensure it frys properly and to increase throughput potential. |
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One for the electrical boys, please ...
On Wed, 13 Apr 2011 17:20:06 +0100, Arfa Daily wrote:
More or less definitive answer coming up...... We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". Right, 3 x 100a supply equates to a nominal maximum capacity of 75 kva. First thing, you need to do is determine your maximum demand allowing for diversity. Will everything be on and working at once? Do the fryers cycle because of thermostats. I'm guessing you're probably going to be looking an MD of about 40-50 kva. Whole current means the installation is connected directly through the meter. A three phase WC meter will have a maximum capacity of about 80 to 100 amps per phase. If you were going for some major industrial process with motors, heating welding and all sorts of other equipment you could be looking at a demand well in excess of 100a per phase. These meters operate using CTs (current transformers), usually 200/5 or 400/5, so the meter is actually taking only a small percentage of the full load current. The incoming cable and main fuses are also much larger. I have not the slightest idea what the difference between these is, or which it will be that we need ?? See above I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Is this a completely new supply or is he extending the installation to give you a sub-main off the existing installation? If that's the case, you'll be paying the landlord through a private meter, nothing to do with the distribution company. Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? Another question on the form is "Voltage - please delete" The three options given are 415V 11kV and 33kV. I assume that the correct answer there is 415V as it's a three phase supply direct into the premises ? 415 volts, but see above. -- The Wanderer When you hear the toilet flush and your child says 'Uh oh' It's already too late! |
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One for the electrical boys, please ...
"The Wanderer" wrote in message ... On Wed, 13 Apr 2011 17:20:06 +0100, Arfa Daily wrote: More or less definitive answer coming up...... We are in the process of taking some modern commercial premises, in which the landlord is dividing down a 2k sq ft unit into two 1k sq ft units, one of which will be ours. The electrical supply comes into the unit that will not be ours, so the landlord is putting a new supply into our bit for us as part of the deal. The currently installed supply is three phase, with each phase company-fused at 100A, as far as I can see. We have approached NPower for a meter, and one of the questions on the application form refers to the type of meter required. The two three phase options given are "Three Phase Whole Current" and "Three Phase CT". Right, 3 x 100a supply equates to a nominal maximum capacity of 75 kva. First thing, you need to do is determine your maximum demand allowing for diversity. Will everything be on and working at once? Do the fryers cycle because of thermostats. I'm guessing you're probably going to be looking an MD of about 40-50 kva. Whole current means the installation is connected directly through the meter. A three phase WC meter will have a maximum capacity of about 80 to 100 amps per phase. If you were going for some major industrial process with motors, heating welding and all sorts of other equipment you could be looking at a demand well in excess of 100a per phase. These meters operate using CTs (current transformers), usually 200/5 or 400/5, so the meter is actually taking only a small percentage of the full load current. The incoming cable and main fuses are also much larger. I have not the slightest idea what the difference between these is, or which it will be that we need ?? See above OK. All understood. That form has now been filled out and faxed to our liason guy at NPower. I have checked with the landlord to make sure that it is a three phase supply that he is bringing over to our unit, and he says that we will "need a three phase meter for a 40kVA supply" First question then. If each phase is currently fused at 100A, does that mean that the incoming supply is 25kVA per phase i.e. 75kVA, and that by dividing it between the two newly created premises, that is how he arrives at 40kVA ? Is this a completely new supply or is he extending the installation to give you a sub-main off the existing installation? If that's the case, you'll be paying the landlord through a private meter, nothing to do with the distribution company. It is a new supply. The landlord has sent us a copy of the letter from EON regarding them putting it in. In that letter, they request that a meter supplier is appointed. However, that said, as he has told us that it will be a 40 kVA supply, I have to assume that EON will be re-working the existing 75 kVA supply into 2 x 40 kVA supplies, one being for us, and one to serve the remaining 1k sq ft unit that is still to be let. Does that make sense ? Our demand will be fairly high. There will be two electrical fryers, each loading at 2 x 9kW, so I guess if they are all on and heating up together, that would be a demand of 36kW. There is also a ceiling mounted airco / heater unit that I don't know the specs for . It's not very big - maybe 2 ft square. Other than that, the demand will be moderately low - some fume extraction which is only a few amps, a couple of small fridges and freezers, lights (not more than 1kW) and small odds and sods for a normal ring main. So, given the *potential* for everything being on together, does that mean that the supply he is proposing giving us, is going to be adequate for our needs ? I have now revisited this, and enquired with my daughter as to why she chose fryer units with such a large power demand. It turns out that it was, to some extent, an 'arbitrary' decision, based on the fact that the particular model in question seemed to be the best value for money, whilst fulfilling our performance needs. She had not considered the potential for two of these gobbling up all of our incoming electricity supply capacity. We have now found another model from the same manufacturer and range, which is 2 x 6 kW per unit. This is capable of a 17 kilo per hour throughput of frozen chips, so we think that two of these will be plenty adequate for the busy nights. So, with those both on, there is the potential for a 24 kW draw worst case, both thermostats on together. Now, a slightly different question arises. According to the specs, this unit can be configured for single phase or two phase operation. What would be the story there ? Would it be both 6 kW elements paralleled up for single phase, and one element on each of two phases for a two phase configuration ? Given the knowledge of what supply we are going to have, which would be the preferred way of hooking them up - all factors such as cost of fittings, cable, labour, practicality for supply loading etc, considered ? Arfa |
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One for the electrical boys, please ...
On Thu, 14 Apr 2011 16:31:05 +0100, Arfa Daily wrote:
"The Wanderer" wrote in message ... OK. All understood. That form has now been filled out and faxed to our liason guy at NPower. snip Is this a completely new supply or is he extending the installation to give you a sub-main off the existing installation? If that's the case, you'll be paying the landlord through a private meter, nothing to do with the distribution company. It is a new supply. OK, that's a new supply to you. The landlord has sent us a copy of the letter from EON regarding them putting it in. In that letter, they request that a meter supplier is appointed. However, that said, as he has told us that it will be a 40 kVA supply, I have to assume that EON will be re-working the existing 75 kVA supply into 2 x 40 kVA supplies, one being for us, and one to serve the remaining 1k sq ft unit that is still to be let. Does that make sense ? I guess the Landlord has told EON to install a 40kva supply, based on what you've said to him[1]. I think you mentioned in your OP that there was already a supply into the original unit and that it was located in the part that wasn't in your tenancy. I would expect that to be left in situ to supply the other half of the building. (Gentle) questions I'd be putting to the LL, is the existing supply remaining for the other half of the building, and has he merely asked for a 40kva supply based on your estimates to him? (You can tell him you just want to be clear about the arrangements.) The distribution compan need a reasonable estimate of maximum demand for any commercial or industrial premises to ensure they are installing the correct cable and equipment to meet that demand. They will install a supply with a nominal maximum capacity of 75kva, even if you only need 40kva. (Single phase will only give a nominal MD of 25 kva, no use to you). snip I have now revisited this, and enquired with my daughter as to why she chose fryer units with such a large power demand. It turns out that it was, to some extent, an 'arbitrary' decision, based on the fact that the particular model in question seemed to be the best value for money, whilst fulfilling our performance needs. She had not considered the potential for two of these gobbling up all of our incoming electricity supply capacity. Unlikely, you finish up with more capacity through the cable and meter than you will need. We have now found another model from the same manufacturer and range, which is 2 x 6 kW per unit. This is capable of a 17 kilo per hour throughput of frozen chips, so we think that two of these will be plenty adequate for the busy nights. So, with those both on, there is the potential for a 24 kW draw worst case, both thermostats on together. Now, a slightly different question arises. According to the specs, this unit can be configured for single phase or two phase operation. What would be the story there ? Would it be both 6 kW elements paralleled up for single phase, and one element on each of two phases for a two phase configuration ? Given the knowledge of what supply we are going to have, which would be the preferred way of hooking them up - all factors such as cost of fittings, cable, labour, practicality for supply loading etc, considered ? If it were me, I'd go for the 9kw models as long as they can be connected across three phases, 3kw per phase. You should aim to keep your load reasonably well balanced across the three phases. [1] It's a while since I had anything to to do with commercial/industrial tariffs, but your LL might be doing you a favour. From memory anything over a nominal 50kva supply will only be metered on a maximum demand tariff. Below 50kvz you have the choice of straight kwh or maximum demand.[2] [2] An MD tariff is most beneficial to a customer with a very high load factor, i.e. he is running continuous processes that are drawing a steady kwh demand more or less continuously. If you have a process that ticks over at a nominal demand of 30kva but for 5 minutes in every hour kicks up to 200kva, you will be penalised because the supply company has needed to install much larger cables that are really only needed for just 5 minutes in every hour. Bit of an over-simplification but I hope that makes sense. -- The Wanderer There is no place like 127.0.0.1 |
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One for the electrical boys, please ...
"The Wanderer" wrote in message ... On Thu, 14 Apr 2011 16:31:05 +0100, Arfa Daily wrote: "The Wanderer" wrote in message ... OK. All understood. That form has now been filled out and faxed to our liason guy at NPower. snip Is this a completely new supply or is he extending the installation to give you a sub-main off the existing installation? If that's the case, you'll be paying the landlord through a private meter, nothing to do with the distribution company. It is a new supply. OK, that's a new supply to you. The landlord has sent us a copy of the letter from EON regarding them putting it in. In that letter, they request that a meter supplier is appointed. However, that said, as he has told us that it will be a 40 kVA supply, I have to assume that EON will be re-working the existing 75 kVA supply into 2 x 40 kVA supplies, one being for us, and one to serve the remaining 1k sq ft unit that is still to be let. Does that make sense ? I guess the Landlord has told EON to install a 40kva supply, based on what you've said to him[1]. I think you mentioned in your OP that there was already a supply into the original unit and that it was located in the part that wasn't in your tenancy. I would expect that to be left in situ to supply the other half of the building. (Gentle) questions I'd be putting to the LL, is the existing supply remaining for the other half of the building, and has he merely asked for a 40kva supply based on your estimates to him? (You can tell him you just want to be clear about the arrangements.) Good point, but I don't think that we entered into any specifics about what our demand would be on any supply, before he told us that it would be a 40 kVA supply that EON would be putting in. The distribution compan need a reasonable estimate of maximum demand for any commercial or industrial premises to ensure they are installing the correct cable and equipment to meet that demand. They will install a supply with a nominal maximum capacity of 75kva, even if you only need 40kva. (Single phase will only give a nominal MD of 25 kva, no use to you). snip I have now revisited this, and enquired with my daughter as to why she chose fryer units with such a large power demand. It turns out that it was, to some extent, an 'arbitrary' decision, based on the fact that the particular model in question seemed to be the best value for money, whilst fulfilling our performance needs. She had not considered the potential for two of these gobbling up all of our incoming electricity supply capacity. Unlikely, you finish up with more capacity through the cable and meter than you will need. We have now found another model from the same manufacturer and range, which is 2 x 6 kW per unit. This is capable of a 17 kilo per hour throughput of frozen chips, so we think that two of these will be plenty adequate for the busy nights. So, with those both on, there is the potential for a 24 kW draw worst case, both thermostats on together. Now, a slightly different question arises. According to the specs, this unit can be configured for single phase or two phase operation. What would be the story there ? Would it be both 6 kW elements paralleled up for single phase, and one element on each of two phases for a two phase configuration ? Given the knowledge of what supply we are going to have, which would be the preferred way of hooking them up - all factors such as cost of fittings, cable, labour, practicality for supply loading etc, considered ? If it were me, I'd go for the 9kw models as long as they can be connected across three phases, 3kw per phase. You should aim to keep your load reasonably well balanced across the three phases. OK. Mostly understood, I think. However, as each of those fryers has 2 x 9 kW of heating elements, would that not equate to 6 kW per phase for each fryer i.e. a total of 12 kW per phase when both fryers are in use, and happen to both be 'statted on at the same time ? Do the three demands then just add up to amount to a grand total of 36 kW ? If so, then that seems to be coming pretty close to the system capacity of 40 kVA (am I right in thinking that for resistive loads kW = kVA ??) Arfa [1] It's a while since I had anything to to do with commercial/industrial tariffs, but your LL might be doing you a favour. From memory anything over a nominal 50kva supply will only be metered on a maximum demand tariff. Below 50kvz you have the choice of straight kwh or maximum demand.[2] [2] An MD tariff is most beneficial to a customer with a very high load factor, i.e. he is running continuous processes that are drawing a steady kwh demand more or less continuously. If you have a process that ticks over at a nominal demand of 30kva but for 5 minutes in every hour kicks up to 200kva, you will be penalised because the supply company has needed to install much larger cables that are really only needed for just 5 minutes in every hour. Bit of an over-simplification but I hope that makes sense. -- The Wanderer There is no place like 127.0.0.1 |
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One for the electrical boys, please ...
On Fri, 15 Apr 2011 02:14:55 +0100, Arfa Daily wrote:
OK. Mostly understood, I think. However, as each of those fryers has 2 x 9 kW of heating elements, would that not equate to 6 kW per phase for each fryer i.e. a total of 12 kW per phase when both fryers are in use, and happen to both be 'statted on at the same time ? Do the three demands then just add up to amount to a grand total of 36 kW ? If so, then that seems to be coming pretty close to the system capacity of 40 kVA (am I right in thinking that for resistive loads kW = kVA ??) No need to worry about it, the supply that is installed will have a nominal capacity of 75kva. You won't be in some way limited just to 40kva. What you need to be aware about, if the busness expands, and you start installing more equipment, you have a ceiling of 75kva. Seems unlikely you'd reach that figure. I'm guessing you are taking the place with an electricity supply, so the landlord has started the ball rolling, rather than telling you to contact the DisCo to make arrangements. He's probably done it before and has the (not unreasonable) figure of 40kva set in his mind as a reasonable demand for the type of unit. It's the sort of figure I would expect to see in a request for supply. As to kva and kwh, yes for resistive loads the two will be more or less the same. As far as all tariffs are concerned units are charged per kwh, not per kvah, but..... Where some industrial processes are concerned, the total demand on the supply may be greater than the load in kw. i.e. a load of 200kw resistive, but a demand of say 220kva. This is because motors and some other equipment don't represent a purely resistive load. Imagine a 5-12-13 right-angled triangle, the 12 side is the resistive load, the 5 side is reactive load at right angles to the resistive load, the 13 side is the actual maximum demand on the supply system. As an aside measuring the demand used to be by using a very clever bit of electro-mechanical metering, a trivector. This had a meter measuring kwh another measuring rkvah, and the two were summated using an awe-inspiring gear train, with all sorts of differentials, epicyclics, the sort of thing to bring a real gleam to the eye of any experimenter here. :-) -- The Wanderer When you hear the toilet flush and your child says 'Uh oh' It's already too late! |
#31
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One for the electrical boys, please ...
Arfa Daily wrote:
We have now found another model from the same manufacturer and range, which is 2 x 6 kW per unit. This is capable of a 17 kilo per hour throughput of frozen chips, so we think that two of these will be plenty adequate for the busy nights. So, with those both on, there is the potential for a 24 kW draw worst case, both thermostats on together. Now, a slightly different question arises. According to the specs, this unit can be configured for single phase or two phase operation. What would be the story there ? Would it be both 6 kW elements paralleled up for single phase, and one element on each of two phases for a two phase configuration ? Given the knowledge of what supply we are going to have, which would be the preferred way of hooking them up - all factors such as cost of fittings, cable, labour, practicality for supply loading etc, considered ? Many normal household hobs come with wiring diagrams for 1, 2 and 3 phase supplies. When using the single phase option then all the live terminal are linked together at the hob. The use of a single phase would need you to balance the other two phases with other appliances. -- Adam |
#32
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One for the electrical boys, please ...
"Huge" wrote in message ... On 2011-04-14, Arfa Daily wrote: This is capable of a 17 kilo per hour throughput of frozen chips, That's a serious chip dependency you have there. But seriously, what is this business? I can't see a chip shop in an industrial unit ... -- Not all 'units' are *industrial* units, and not all places that serve chips, are 'chip shops' ... !! It is a retail unit, in a terrace of other retail units, and we will be selling mainly American-style char-grilled burgers. Sort of 'quality' junk food, if you like ... :-) Arfa |
#33
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One for the electrical boys, please ...
"Huge" wrote in message ... On 2011-04-15, Arfa Daily wrote: "Huge" wrote in message ... On 2011-04-14, Arfa Daily wrote: This is capable of a 17 kilo per hour throughput of frozen chips, That's a serious chip dependency you have there. But seriously, what is this business? I can't see a chip shop in an industrial unit ... Not all 'units' are *industrial* units, and not all places that serve chips, are 'chip shops' ... !! It is a retail unit, in a terrace of other retail units, and we will be selling mainly American-style char-grilled burgers. Ah, OK. The very best of luck to you. Why thank you, kind sir ! Actually, should be a success. My wife and daughter have run food outlets for quite a long time, and been very successful at it. They sold both their cafes recently, in order to finance this latest project, that they've wanted to do for some time. It is actually very hard to get a decent take out burger from anywhere. Mostly, your only option is Burger King for a mass produced flame grilled burger, Mickey D's for a mass produced griddled burger, or the local chip shop for a poorly hand-made griddled or microwaved cheeseburger. There is a quality char-grilled burger take out in a town not far from me, and he celebrated 30 years a few months ago. His quality both of product and staff has never dropped in all that time, and I think that has got a lot to do with his ongoing success. It has taken us a long time to find suitable premises. One of the big stumbling blocks is getting A5 planning. The landlord had just applied on this unit when we were first interested. A local councilor did object, but he was over-ruled by the rest of the committee on the grounds that it was better to have the unit doing something rather than standing empty, and that there was already a precedent set by other food establishments in the same retail area. There is very good footfall to a late night supermarket, and a massive pool of housing surrounding the area on three sides, and a large free car park serving the shops right outside. Also, a large pub across the road, and an industrial estate at the other end of the road that the complex sits on, as well as a main road connecting this town to the next one, just a hundred yards away, so we are hopeful that it will be really successful. I think many businesses like this fail due to wrong location, lack of business savvy, and wrong attitude to customer service. This is an 'eyes wide open' enterprise that the girls are embarking upon, and one that they are bringing a big chunk of business and food expertise to .... Arfa |
#34
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One for the electrical boys, please ...
Arfa Daily wrote:
"Huge" wrote in message ... On 2011-04-15, Arfa Daily wrote: "Huge" wrote in message ... On 2011-04-14, Arfa Daily wrote: This is capable of a 17 kilo per hour throughput of frozen chips, That's a serious chip dependency you have there. But seriously, what is this business? I can't see a chip shop in an industrial unit ... Not all 'units' are *industrial* units, and not all places that serve chips, are 'chip shops' ... !! It is a retail unit, in a terrace of other retail units, and we will be selling mainly American-style char-grilled burgers. Ah, OK. The very best of luck to you. Why thank you, kind sir ! Actually, should be a success. My wife and daughter have run food outlets for quite a long time, and been very successful at it. They sold both their cafes recently, in order to finance this latest project, that they've wanted to do for some time. It is actually very hard to get a decent take out burger from anywhere. Mostly, your only option is Burger King for a mass produced flame grilled burger, Mickey D's for a mass produced griddled burger, or the local chip shop for a poorly hand-made griddled or microwaved cheeseburger. There is a quality char-grilled burger take out in a town not far from me, and he celebrated 30 years a few months ago. His quality both of product and staff has never dropped in all that time, and I think that has got a lot to do with his ongoing success. It has taken us a long time to find suitable premises. One of the big stumbling blocks is getting A5 planning. The landlord had just applied on this unit when we were first interested. A local councilor did object, but he was over-ruled by the rest of the committee on the grounds that it was better to have the unit doing something rather than standing empty, and that there was already a precedent set by other food establishments in the same retail area. There is very good footfall to a late night supermarket, and a massive pool of housing surrounding the area on three sides, and a large free car park serving the shops right outside. Also, a large pub across the road, and an industrial estate at the other end of the road that the complex sits on, as well as a main road connecting this town to the next one, just a hundred yards away, so we are hopeful that it will be really successful. I think many businesses like this fail due to wrong location, lack of business savvy, and wrong attitude to customer service. This is an 'eyes wide open' enterprise that the girls are embarking upon, and one that they are bringing a big chunk of business and food expertise to .... Sounds a brilliant plan Only thing to object to apart from late night disturbances would be the smell of greasy frying ! And your daughter appears to have realised something that is blindingly obvious to all but the catering trade: food costs in this kind of enterprise are typically very low. Maybe 10% or less. A **** burger (or whatever) will cost 2 quid (20p food cost), a really **** burger 1.95 (5p food cost), and you can do a really good one for £2.50,.(60p food cost) for the same overall gross profit per burger. I mean, we can cook, using retail priced Waitrose special buns and burgers, and salads, a fantastically delicious burger for about £1.50 food cost each.If the cooking and overheads contribute the same margin - say £1.90 - then a completely gourmet burger is £4.40! |
#35
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One for the electrical boys, please ...
In article , Huge
writes I can understand that. A good burger is a delight. My local pub does hand-made burgers. Bit pricey at a fiver, but you get chips, salad and onion rings too. The chilli and coriander burgers are to die for. -- (\__/) (='.'=) (")_(") |
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