soft start

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=106228
Printed Date: May 16, 2025 at 8:36 AM

Topic: soft start

Posted By: ashbyspannerman
Subject: soft start
Date Posted: July 19, 2008 at 4:26 AM

hi i'm running a 240 volt fridge through a 1500 watt inverter, i want to do away with the waste of having the inverter on continuosley. i have managed to tap into the thermostat on the fridge and use that to turn on the inverter 'on demand' the prob is that the inverter seems to 'ramp up' and won't power the fridge comp if the demand is there before the inverter is on! the inverter is fine for operating the fridge, i just need a way of delaying the demand, so that the thermostat turns on the inverter and then maybe a couple of seconds later a relay closes allowing the fridge to draw power after the inverter has fully powered.
any ideas?

Replies:

Posted By: Big Dog
Date Posted: July 21, 2008 at 3:24 PM

I'm sure you can do something with this module: TR7

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Prepare your future. It wasn't the lack of stones that killed the stone age.

Posted By: ashbyspannerman
Date Posted: July 22, 2008 at 2:00 PM

that looks dooable, i'll have a look to see if i can get hold of one of those, thanks.

Posted By: hotwaterwizard
Date Posted: July 26, 2008 at 6:59 PM

You will probably have to switch the 220 vac on a delay circuit not the 12vdc.

You will need a Motor Start Contactor and a Timer module rated at 220vac.

I can come up with a wiring diagram for you if you like.

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: hotwaterwizard
Date Posted: July 26, 2008 at 7:26 PM

Grainger.com ships world wide. here is what I came up with.
The timer gets its power from the inverter when it is turned on by the Thermostat.
The timer will time out and turn on the Contactor.
The contactor L1 L2 L3 all get power from the Inverter.
The Fridge is hooked to T1 T2 T3 and gets power after the set delay on the timer.

https://www.grainger.com/Grainger/items/5JJ47

posted_image

https://www.grainger.com/images/products/enlarged/XL-5JJ47.JPG

https://www.grainger.com/Grainger/items/5B121

posted_image

https://www.grainger.com/images/products/enlarged/XL-5B120.JPG

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !