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Discussion Starter #1 (Edited)
When I did the design of this job I thought it would be much easier but now that I am looking for actual parts it is not as nice as I thought it would be. I need to be able to drop a generator that is powering a house by means of a toggle switch. So I need a contactor that has a 120v coil and contacts that are rated for the house load.

The generator has a 100a main circuit breaker. The more conventional looking contactors I have been able to find have something like a 90a motor rating/130a resistive rating. These are probably fine but I am concerned what an inspector might say. Also, I saw some "pump panels" out there that had contactor and enclosure as one and this would be nice as it will be found in a 3R environment. But the pump panels have switches and buttons which I don't want or need.

Prices are all over the place. I am hoping somebody has a ready idea on what part number might be the most appropriate for this application.
 

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When I did the design of this job I thought it would be much easier but now that I am looking for actual parts it is not as nice as I thought it would be. I need to be able to drop a generator that is powering a house by means of a toggle switch. So I need a contactor that has a 120v coil and contacts that are rated for the house load.

The generator has a 100a main circuit breaker. The more conventional looking contactors I have been able to find have something like a 90a motor rating/130a resistive rating. These are probably fine but I am concerned what an inspector might say. Also, I saw some "pump panels" out there that had contactor and enclosure as one and this would be nice as it will be found in a 3R environment. But the pump panels have switches and buttons which I don't want or need.

Prices are all over the place. I am hoping somebody has a ready idea on what part number might be the most appropriate for this application.
What do you mean by "drop a generator"?? Is the generator powering the house and the utility comes back on?

On the pump panels, why not just disconnect the switches and buttons you don't want/need?

Is this some kind of home made transfer switch? If so, you'd best make sure that there is no way you can back feed the utility or you might be in for more headaches than you want...
 

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Why are you going through all that bother? If you need to drop the generator by a toggle switch, why not just use a toggle switch to kill the engine? :rolleyes:

In any event, to do it any other way you will need to do two things:

1: Have a qualified EE design or spec something to drop that much load.
2: Hire a qualified professional electrician to install the equipment as specified by the qualified EE.

Thread closed.
 

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Ok, after some discussion with the OP via PM, I am reopening this thread.

There was some info omitted from the OP that needs to be added to the mix:

From OP PM said:
We are using a transfer switch as per normal but the customer wants to be able to shut off the generator during a prolonged outage.

I realize most people just cut off the power to the generator and let it stop as will I. However, it is not good practice to allow a generator to start up or shut down with the load connected so a simple contactor will suffice to drop the load gracefully.

I was hoping someone would have a ready part number because the selection of possibilities for said contactor are almost mind boggling.

I know this is out of the ordinary but this is what the customer wants; he does not want to have to go out to the generator and shut off the MCB and ignition switch but to do it remotely.

The generator (proposed) is just a 22kw Generac, nothing special.
I want to bring up the following points as well:

1: The only Code-Compliant solution I see is if the generator manufacturer can provide a shunt-trip MCB and the ability to kill the engine remotely.

2: As for a contactor, other than transfer switches, I am not aware of ANY contactors that are rated as suitable for service equipment.

3: In any event I do see that there might be issues with getting your inspector to sign off on anything that is not listed/approved as an assembly for that particular generator. Your power company may also refuse to connect to the system if it is not listed/approved.

Now that we have more pertinent info, the question remains, is anyone aware of a solution to this problem that will be safe, Code-Compliant and not a possible issue with the AHJ or POCO?
 

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We installed a T switch that had a modem interface quite a while ago , at the request of an out of state customer.

They had the ability to patch in all manner of internet toys for the monitoring and control of it all....

Not that i'm much help on the specifics of it :(, but i would be asking the genny or ATS manufacturers the OP's Q...;)


~CS~
 

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Discussion Starter #10 (Edited)
Thanks for bringing up the service entrance issue. However, only some transfer switches are service rated and in this case we do not need one of them because the transfer switch is running off a 100A branch breaker in the main panel which then feeds its own subpanel. I guess that would not even make it a service entrance since there are 2 or so circuits still on the main panel that the generator doesn't power?

The contactor and its enclosure would be remotely mounted on the wall, in the conduit most likely somewhere near the transfer switch. No modification to the generator is necessary other than to use 2-wire start and that is well documented.

A shunt trip would be fine but that eliminates the possibility of restarting the machine remotely which is what the customer wants.
 

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Glad I read the last post as a shunt trip wouldn't work. How remote are we looking to do this. Why not simply use a manual discO? And have auxiliary contacts wired in that upon break it maybe has some sort of delay timer that will kill unit as to not damage brushes.

To restart use auxiliary contacts on disconnect need to be made and use a start button to close loop on starter coil and ignition and gas solenoid. That should be able to disconnect the load quick enough but not sure how much I like the idea plus if he's looking for more of a remote option say in the house /kitchen a knife wouldn't look so hot
 

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The start contacts would obviously have to be 12 volt battery sourced. And it would need to be 2 sets of auxiliary contacts.

Only other thing I'm coming up with would void a generac warranty but to introduce a 240 volt switch to imitate grid power and pull the coil back to utility that would disconnect it then we would want a start stop station to kill the engine. Via 12 volts. Once the generator warms down and shuts off you will use your push buttons 12 volt 2 wore start once it's up and running again it will transfer back to gen .
 

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McClary his client doesn't want to go outside . Wants a remote option and other than my last post I can't think of anything else besides utilizing the transfer switch and straight up voiding the warranty on transfer switch. Definitely make sure customer is willing to do that because I can't think of any other way to disconnect load safety other than using transfer switch or manual disco.
 

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McClary his client doesn't want to go outside . Wants a remote option and other than my last post I can't think of anything else besides utilizing the transfer switch and straight up voiding the warranty on transfer switch. Definitely make sure customer is willing to do that because I can't think of any other way to disconnect load safety other than using transfer switch or manual disco.
Ok I missed that. This can be done with a 24 volt to 120 volt transformer. The transfer switch doesn't sense 240 volt it will transfer with loss of one leg. Run the secondary of the transformer through one set of n.o. contacts on a selector switch. Run 192 and 93 through two other sets of n.c contacts.
 

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I am just wondering if we could make use of the two wire start capability in these and insert some switching into the mix. Maybe use an asco transfer switch as well. Still could insert a contactor after the transfer switch between the load to drop it out.
 

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Discussion Starter #18 (Edited)
I left out the control wiring, we are using an Asco type transfer switch (which model is unknown at this point). So wire 194 and 23 will not have control of it, it has control of itself. And N1 and N2 become contact closure input like a commercial unit and transfer switch.

I would love to figure out some way to force the transfer switch back into the utility position and I may well end up doing that, but it would be even more custom than the contactor idea.

I just hate doing custom work inside a package like a transfer switch because everything has to be thought out so carefully to avoid unintended consequences. But I have done it before so maybe I will have to do it again. I just want to do it without introducing unreliable components into the mix.

A contactor, in a box, with a toggle switch, would satisfy these requirements but I need to find the right contactor. All I was really after was the right current ratings, i.e. something with a FLA of over 90.
 

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I'm thinking of a generac switch in my head since I was out troubleshooting a transfer yesterday. I fired you could tap 240 volt off of e1 and e2 to line side of switch and load side of switch one wire would go to utility coil and one to the limit switch. That would get it to switch but you would have to put a emergency stop in line of the start circuit so that after it did transfer and shut down it would restart and retransfer.

So customer would flip a 240 volt switch to throw transfer to utility then once we knew that was safe and disconnected to hit a e button to kill genny. Resetting e button and pushing start would start unit and it would auto transfer once running.
 

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Discussion Starter #20
That is basically what I would like to do but there is no provision for that in the genset controller, to start and stop on command. You can convert the genset to start and stop on a 2 wire contact closure input but once you do that your utility monitoring goes away and you can't use the Generac cheap transfer switch any more.

Maybe I could do the same thing with the Asco style switch but I don't have one in front of me to play with and not knowing how they are wired ahead of time, it is too risky to go and buy one and then see if it works for me or not.

Fortunately I have a job on Monday where there is a Thomson transfer switch of the same style so we will see how that one works internally.

Thanks for the ideas.
 
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