Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old August 10th 20, 09:22 PM posted to sci.electronics.repair
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Default Solid state relay questions

On Mon, 10 Aug 2020 11:20:54 -0700 (PDT), "
wrote:

Could you please
explain why a relay controlled by a remote switch is a bad idea? BTW,
thanks for the links.


a) Because a relay is _NOT_ typically rated for motor-start loads.
b) Because a relay is not designed for the purpose you suggest.
c) Because a relay does not accept abuse very well.

Whereas:
a) A definite-purpose contactor _IS_ rated for whatever motor load you choose (it's only money).
b) A definite-purpose contactor _IS_ designed to turn motors on and off, as needed and as often as needed.
c) A definite-purpose contactor _MAY_ be designed against any number of coil voltages.
d) A definite-purpose contactor _IS_ quite reliable if installed correctly.
e) A definite-purpose contactor will take a great deal of abuse. In point of fact, they were developed for exactly the sort of scenario you suggest.

Again - this venue may often get used as a means to avoid the safe-and-correct solution in preference for the Kluge solution - but that does not make that solution correct, nor safe, nor reasonable.

Keep in mind that any problem with electricity, motors, and controls for same has, at some point in the last 130 years or so, been addressed and managed. Most, quite elegantly. Reinventing a simple wheel only for the sake of that reinvention is always futile, often silly, and all too often, dangerous.

Peter Wieck
Melrose Park, PA

I guess I should have said contactor, which is just a special type of
relay.
Eric

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Old August 10th 20, 10:34 PM posted to sci.electronics.repair
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Default Solid state relay questions

Much as a Ducati or a Triumph or a BMW is a special sort of Scooter.

Peter Wieck
Melrose Park, PA
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Old August 11th 20, 10:26 AM posted to sci.electronics.repair
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Default Solid state relay questions

On 10/08/2020 21:34, wrote:
Much as a Ducati or a Triumph or a BMW is a special sort of Scooter.


https://en.wikipedia.org/wiki/Contactor

--
Adrian C
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Old August 11th 20, 10:49 PM posted to sci.electronics.repair
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Default Solid state relay questions

On Sunday, August 9, 2020 at 9:26:55 PM UTC-4, wrote:
Line drop. Bull****. Use #6 copper UF cable, and the line-drop for a 400-foot run is 2.53 volts at 8 amps (1920 watts).

Repeat: cut the BS and do it right.



Or use a boost transformer to compensate for the drop, but only to power the pump.

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Old August 13th 20, 02:33 PM posted to sci.electronics.repair
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Default Solid state relay questions

On Saturday, August 8, 2020 at 3:40:57 PM UTC-4, wrote:
My water comes from a well. When the well was drilled I had only
built my shop and so the well is now powered by my shop. The pressure
tank and switch is also at the shop.
Now that the house is built I need to power the well from the
house. This is fine but I am not gonna move the pressure tank and the
pump switch must be at the tank for proper operation.
The problem I must address is how to use the switch at the tank
while using power from the house. I cannot run power from the house to
the tank and then to the well pump because the voltage drop would be
too great due to the much longer run of wire.
My plan is to instead use the existing wires coming from the shop
and going to the well to just carry switching power, not pump power. I
want to use a couple solid state relays, one for each leg of the 240
power, to switch the power to the well. There is plenty of room to
mount two solid state relays inside the well junction box. And I found
AC controlled solid state relays that use 80 to 280 volts AC for
control and will switch up to 480 volts AC at 25 amps. My well pump is
a 2 HP pump that draws less than 10 amps. It is a capacitor start
type pump so it draws less current at start up than a non-capacitor
type pump.



Why isn't the switch at the pump? How are you going to get power from the house to the pump, without new a new power line?


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Old August 13th 20, 02:52 PM posted to sci.electronics.repair
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Default Solid state relay questions

Why isn't the switch at the pump? How are you going to get power from the house to the pump, without new a new power line?

After all this confusion - I expect that the OP means to "control" the pump from the house. If I can interpret the issue (risky, always).
a) The house has a back-up generator.
b) The line to the pump is from the house, but the power to the tank is from the shop, not backed up.
c) The pressure switch is at the tank.

I interpret this to mean that a 120V pressure-switch is controlling a 240V pump, powered by two different sources. Which is flat-out nuts.

I am interpreting (again, risky) that the OP wants the controls at the pump.

So, the 120V source at the shop will control a 240V (hopefully) contactor at the pump.

All the while forgetting that if there is a power-failure, that 120V source will be dead - so, no water.

Clue 1: The tank does not care where it is in the system.
Clue 2: The tank will be perfectly happy staying where it is, with all controls, pressure-switch, contactor and so forth at the pump - in suitable enclosures, of course.

Peter Wieck
Melrose Park, PA

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Old August 13th 20, 06:00 PM posted to sci.electronics.repair
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Default Solid state relay questions

On Thu, 13 Aug 2020 05:52:00 -0700 (PDT), "
wrote:

Why isn't the switch at the pump? How are you going to get power from the house to the pump, without new a new power line?


After all this confusion - I expect that the OP means to "control" the pump from the house. If I can interpret the issue (risky, always).
a) The house has a back-up generator.
b) The line to the pump is from the house, but the power to the tank is from the shop, not backed up.
c) The pressure switch is at the tank.

I interpret this to mean that a 120V pressure-switch is controlling a 240V pump, powered by two different sources. Which is flat-out nuts.

I am interpreting (again, risky) that the OP wants the controls at the pump.

So, the 120V source at the shop will control a 240V (hopefully) contactor at the pump.

All the while forgetting that if there is a power-failure, that 120V source will be dead - so, no water.

Clue 1: The tank does not care where it is in the system.
Clue 2: The tank will be perfectly happy staying where it is, with all controls, pressure-switch, contactor and so forth at the pump - in suitable enclosures, of course.

Peter Wieck
Melrose Park, PA

The tank and pressure switch are at the shop and have been so for
over 20 years. The pressure switch has two contacts. The 240 volt
power from the shop, where the tank and pressure switch are, is
switched by the pressure switch. The pressure switch has a completely
mechanical action. The pressure switch switches both legs of the 240
volt power.
When the house was built and I was digging ditches I put conduit in
the ground from the house to the well so that I could eventually power
the well from the house.
Now that I have the generator panel and transfer switch installed
and bought off at the house I want to power the well from the house so
that the generator will be able to power the well when the power goes
out.
I pulled wire from the house to the well to supply power, so now
power from the house is at the well head.
The pressure switch must be located at the pressure tank for proper
operation.
I am not going to move the pressure tank.
So all I want to do is to use the existing pressure switch to
switch the power to a contactor coil. The power for the contactor
coil that the pressure switch will be switching will be coming from
the house. The contactor will be switching the power coming from the
house. There will no longer be any power coming from the shop. Nowhere
did I say any switch was 120 volts. What is wrong with doing this?
Eric
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Old August 13th 20, 06:09 PM posted to sci.electronics.repair
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Default Solid state relay questions

On Thursday, August 13, 2020 at 8:52:05 AM UTC-4, wrote:
Why isn't the switch at the pump? How are you going to get power from the house to the pump, without new a new power line?


After all this confusion - I expect that the OP means to "control" the pump from the house. If I can interpret the issue (risky, always).
a) The house has a back-up generator.
b) The line to the pump is from the house, but the power to the tank is from the shop, not backed up.
c) The pressure switch is at the tank.

I interpret this to mean that a 120V pressure-switch is controlling a 240V pump, powered by two different sources. Which is flat-out nuts.

I am interpreting (again, risky) that the OP wants the controls at the pump.

So, the 120V source at the shop will control a 240V (hopefully) contactor at the pump.

All the while forgetting that if there is a power-failure, that 120V source will be dead - so, no water.

Clue 1: The tank does not care where it is in the system.
Clue 2: The tank will be perfectly happy staying where it is, with all controls, pressure-switch, contactor and so forth at the pump - in suitable enclosures, of course.



He could have easily buried a new power line to the tank when he installed the plumbing, as well. I am rebuilding my pumphouse and rewiring it. It will have a couple AC Ammeters and a line voltage meter to monitor the pump's health, along with a one minute lockout between pump cycles. Te old pump failed, but All I could check was the voltage, since there were no current transformers in place. One till monitor the current to the run winding,, the other will show total current. The voltmeter's use is obvious. The timer is to prevent overheating of the start capacitor, if the potential relay fails, again. I have a new submersible pump, and two pump control boxes, so it an be swapped out without waiting for spare parts. The old pump lasted 22 years. That is a long life, with Florida's very hard water.
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Old August 13th 20, 06:16 PM posted to sci.electronics.repair
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Default Solid state relay questions

On Thursday, August 13, 2020 at 12:00:47 PM UTC-4, wrote:
On Thu, 13 Aug 2020 05:52:00 -0700 (PDT), Peter Wieck wrote:

Why isn't the switch at the pump? How are you going to get power from the house to the pump, without new a new power line?


After all this confusion - I expect that the OP means to "control" the pump from the house. If I can interpret the issue (risky, always).
a) The house has a back-up generator.
b) The line to the pump is from the house, but the power to the tank is from the shop, not backed up.
c) The pressure switch is at the tank.

I interpret this to mean that a 120V pressure-switch is controlling a 240V pump, powered by two different sources. Which is flat-out nuts.

I am interpreting (again, risky) that the OP wants the controls at the pump.

So, the 120V source at the shop will control a 240V (hopefully) contactor at the pump.

All the while forgetting that if there is a power-failure, that 120V source will be dead - so, no water.

Clue 1: The tank does not care where it is in the system.
Clue 2: The tank will be perfectly happy staying where it is, with all controls, pressure-switch, contactor and so forth at the pump - in suitable enclosures, of course.

Peter Wieck
Melrose Park, PA

The tank and pressure switch are at the shop and have been so for
over 20 years. The pressure switch has two contacts. The 240 volt
power from the shop, where the tank and pressure switch are, is
switched by the pressure switch. The pressure switch has a completely
mechanical action. The pressure switch switches both legs of the 240
volt power.
When the house was built and I was digging ditches I put conduit in
the ground from the house to the well so that I could eventually power
the well from the house.
Now that I have the generator panel and transfer switch installed
and bought off at the house I want to power the well from the house so
that the generator will be able to power the well when the power goes
out.
I pulled wire from the house to the well to supply power, so now
power from the house is at the well head.
The pressure switch must be located at the pressure tank for proper
operation.
I am not going to move the pressure tank.
So all I want to do is to use the existing pressure switch to
switch the power to a contactor coil. The power for the contactor
coil that the pressure switch will be switching will be coming from
the house. The contactor will be switching the power coming from the
house. There will no longer be any power coming from the shop. Nowhere
did I say any switch was 120 volts. What is wrong with doing this?


I have never seen one installed that way. Why not just put the pressure switch at the house, if you insist on not locating it at the pump? That would eliminate all of the jury rigged crap that wouldn't pass an inspection.
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Old August 14th 20, 03:38 PM posted to sci.electronics.repair
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Default Solid state relay questions

Comments:

1. use a definite purpose contactor.

2. the pressure switch might have a minimum load, so if those contacts are used to switch a relay coil, they may fail.


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