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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions.

Soft Start



 
 
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  #1  
Old May 5th 11, 07:39 PM posted to uk.d-i-y
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Posts: 2,155
Default Soft Start

Anyone know whether it's possible to add soft start to a tool that
wasn't born with it - maybe by using some external plug-in wizardry?

I have a Lidl compressor which, according to my power meter, takes about
750 watts[1] when running.

I tried to run it today from my Honda 2kW (peak - 1.6kW continuous)
inverter-based generator, and the genny didn't want to know - presumably
because of the high start-up current.

Would a soft start help and, if so, can it be retro-fitted?

[1] Probably 1000VA with a non-unity power factor because the indicated
current was about 4 amps
--
Cheers,
Roger
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  #2  
Old May 5th 11, 08:27 PM posted to uk.d-i-y
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Posts: 2,364
Default Soft Start

On May 5, 7:39*pm, Roger Mills wrote:
Anyone know whether it's possible to add soft start to a tool that
wasn't born with it - maybe by using some external plug-in wizardry?

I have a Lidl compressor which, according to my power meter, takes about
750 watts[1] when running.

I tried to run it today from my Honda 2kW (peak - 1.6kW continuous)
inverter-based generator, and the genny didn't want to know - presumably
because of the high start-up current.

Would a soft start help and, if so, can it be retro-fitted?

[1] Probably 1000VA with a non-unity power factor because the indicated
current was about 4 amps
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.


You can add soft start to machinery - with an inverter (I guess the
same as in your genny, just with lots of user settings on it) - but I
don't think it will reduce the current draw.

I bought an old 3-phase bandsaw, and added an inverter to that (an
Omron IIRC), and it has endless settings for things like ramping up
the Hz - and every other imaginable characteristic of power
management.

Does an excellent job, but not cheap.
  #3  
Old May 5th 11, 08:44 PM posted to uk.d-i-y
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Posts: 9,216
Default Soft Start

On May 5, 7:39*pm, Roger Mills wrote:
Anyone know whether it's possible to add soft start to a tool that
wasn't born with it - maybe by using some external plug-in wizardry?

I have a Lidl compressor which, according to my power meter, takes about
750 watts[1] when running.

I tried to run it today from my Honda 2kW (peak - 1.6kW continuous)
inverter-based generator, and the genny didn't want to know - presumably
because of the high start-up current.

Would a soft start help and, if so, can it be retro-fitted?

[1] Probably 1000VA with a non-unity power factor because the indicated
current was about 4 amps
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.


The compressor might need and an unloading valve. ie, releases air
pressure in the compressor before it starts to reduce the start
current.
  #4  
Old May 5th 11, 09:03 PM posted to uk.d-i-y
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Posts: 1,532
Default Soft Start

On May 5, 7:39*pm, Roger Mills wrote:
Anyone know whether it's possible to add soft start to a tool that
wasn't born with it - maybe by using some external plug-in wizardry?


yes

I have a Lidl compressor which, according to my power meter, takes about
750 watts[1] when running.

I tried to run it today from my Honda 2kW (peak - 1.6kW continuous)
inverter-based generator, and the genny didn't want to know - presumably
because of the high start-up current.

Would a soft start help and, if so, can it be retro-fitted?


well... compressors are not normally soft started, they need a good
current surge to get going in the face of high pressure. You can soft
start them, but would need to take the pressure off them until theyre
upto speed. How easy it is to arrange the additional mechanics on your
compressor I dont know.

It will also work on soft start as is if you start with an empty tank,
and switch it off once full so it doesnt try to top it up. Might or
might not be practical though.

[1] Probably 1000VA with a non-unity power factor because the indicated
current was about 4 amps


http://wiki.diyfaq.org.uk/index.php?title=Droppers


NT
  #6  
Old May 5th 11, 11:21 PM posted to uk.d-i-y
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Posts: 1
Default Soft Start

On Thu, 05 May 2011 19:39:55 +0100, Roger Mills wrote:

Anyone know whether it's possible to add soft start to a tool that
wasn't born with it - maybe by using some external plug-in wizardry?

I have a Lidl compressor which, according to my power meter, takes about
750 watts[1] when running.

I tried to run it today from my Honda 2kW (peak - 1.6kW continuous)
inverter-based generator, and the genny didn't want to know - presumably
because of the high start-up current.

Would a soft start help and, if so, can it be retro-fitted?

[1] Probably 1000VA with a non-unity power factor because the indicated
current was about 4 amps


Does it start ok when there is no pressure in the receiver? If so then you
could add a three port solenoid operated valve between the compressor and
the receiver. The valve can vent the compressor output to atmosphere when
the motor power is removed and re-connect the compressor output to the
receiver a few seconds after the motor is powered up. It wouldn't be cheap
though.

SteveW
  #7  
Old May 6th 11, 08:33 AM posted to uk.d-i-y
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Posts: 1,320
Default Soft Start

Steve Walker wrote:
On Thu, 05 May 2011 19:39:55 +0100, Roger Mills wrote:

Anyone know whether it's possible to add soft start to a tool that
wasn't born with it - maybe by using some external plug-in wizardry?

I have a Lidl compressor which, according to my power meter, takes about
750 watts[1] when running.

I tried to run it today from my Honda 2kW (peak - 1.6kW continuous)
inverter-based generator, and the genny didn't want to know - presumably
because of the high start-up current.

Would a soft start help and, if so, can it be retro-fitted?

[1] Probably 1000VA with a non-unity power factor because the indicated
current was about 4 amps


Does it start ok when there is no pressure in the receiver? If so then you
could add a three port solenoid operated valve between the compressor and
the receiver. The valve can vent the compressor output to atmosphere when
the motor power is removed and re-connect the compressor output to the
receiver a few seconds after the motor is powered up. It wouldn't be cheap
though.

SteveW

Aldi/Lidl type compressors I have seen already have a dump valve
arrangement fitted.

Bob
  #8  
Old May 6th 11, 01:43 PM posted to uk.d-i-y
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Posts: 2,155
Default Soft Start

On 05/05/2011 23:21, Steve Walker wrote:
On Thu, 05 May 2011 19:39:55 +0100, Roger Mills wrote:

Anyone know whether it's possible to add soft start to a tool that
wasn't born with it - maybe by using some external plug-in wizardry?

I have a Lidl compressor which, according to my power meter, takes about
750 watts[1] when running.

etc



Does it start ok when there is no pressure in the receiver?


Dunno - I'll try it.

If so then you
could add a three port solenoid operated valve between the compressor and
the receiver. The valve can vent the compressor output to atmosphere when
the motor power is removed and re-connect the compressor output to the
receiver a few seconds after the motor is powered up. It wouldn't be cheap
though.


An interesting solution. I'm not going to spend much money on anything
though, because it was just an experiment to see whether I could operate
it away from a mains power supply - but I have no compelling need to
actually do that.
--
Cheers,
Roger
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  #9  
Old May 6th 11, 01:53 PM posted to uk.d-i-y
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Posts: 2,155
Default Soft Start

On 06/05/2011 08:33, Bob Minchin wrote:

Aldi/Lidl type compressors I have seen already have a dump valve
arrangement fitted.



Mine has a ring-pull valve to de-pressurise the receiver - is that what
you mean?

It *might* work with the genny if I turn it on and off manually,
completely exhausting the pressure each time - but that wouldn't be very
efficient.

In normal operation the motor is controlled by a pressure switch with
some hysteresis between on and off pressures - so it cuts out when it
gets to max pressure, and turns it on again when the pressure falls a
bit (but still way above zero).
--
Cheers,
Roger
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Please reply to Newsgroup. Whilst email address is valid, it is seldom
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  #10  
Old May 6th 11, 02:03 PM posted to uk.d-i-y
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Posts: 3,654
Default Soft Start

Roger Mills wrote:
Anyone know whether it's possible to add soft start to a tool that
wasn't born with it - maybe by using some external plug-in wizardry?

I have a Lidl compressor which, according to my power meter, takes about
750 watts[1] when running.

I tried to run it today from my Honda 2kW (peak - 1.6kW continuous)
inverter-based generator, and the genny didn't want to know - presumably
because of the high start-up current.

Would a soft start help and, if so, can it be retro-fitted?

[1] Probably 1000VA with a non-unity power factor because the indicated
current was about 4 amps


If it's a squirrel cage motor or capacitor start, then it'll take a
massive surge at start-up. The only generators I've met that will cope
have been old ones with a massive flywheel on the engine.

--
Tciao for Now!

John.
 




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