[mdfriday]

I recently installed a 14KW single phase (120/240V) unit for a local business. They purchased the generator and the 16 ckt 100A transfer switch. Building utility voltage is 277/480V, stepped down to 120/208 at the panel I fed from.

I went today to test the generator for proper functionaltiy. I opened the 60A circuit breaker feeding the ATS (Utility power) to test the auto function. The generator started and the ATS transferred to generator power. We let it run for 10 minutes or so. Then I closed the breaker supplying utility power to the ATS. The ATS would not transfer power back over, nor did the generator shut down.

I did a manual shut down of the generator and manually transferred the power back to utility in the ATS.

All connections checked out and voltage and hertz were correct. It is Generac Equipment.

Can anyone lead me to a solution. I have scoured the manuals and have not found any way to fix this issue.

Thanks!

 

[NJWVUGrad]

How long did you wait for?

Some ATS's have a time delay for returning to utility power.

 

[macmikeman]

Recheck the connections on the 240 v sensor wiring.

 

[mdfriday]

How long did you wait for?

Some ATS's have a time delay for returning to utility power.

5-10 minutes

 

[glen1971]

5-10 minutes

Most of the ones I've worked on have a 10-15 minute delay on seeing a stable Utility Source. Might want to check that setting on yours and see its value.

 

[Meadow]

208 and 240 volt sounds like a potential cause.


Also is this single or tri phase for the ATS? From the description it sounds like a single phase generator on a 3 phase system.

 

[Meadow]

My theory is the drop out voltage is set very low while the pick up is over 208. Hence why it never transferred but it isn't now after manual start up.

 

[mdfriday]

208 and 240 volt sounds like a potential cause.


Also is this single or tri phase for the ATS? From the description it sounds like a single phase generator on a 3 phase system.

Generator is single phase 120/240. ATS is fed from a two pole breaker from a three phase panel.

I was thinking that may be the issue when I was standing there waiting for it to transfer back to utility power...the 240V vs 208V thing....but then I thought, if that were the case, why would it not instantly start the generator when you put it in auto mode since it would not sense the 240V it is looking for...

 

[Meadow]

Generator is single phase 120/240. ATS is fed from a two pole breaker from a three phase panel.

I was thinking that may be the issue when I was standing there waiting for it to transfer back to utility power...the 240V vs 208V thing....but then I thought, if that were the case, why would it not instantly start the generator when you put it in auto mode since it would not sense the 240V it is looking for...

Check the pick up and drop out voltages, are they adjustable? The drop out voltage might be at 200 volts so 208 satisfies the requirement, hence no transfer. Low drop out settings are often to prevent nuisance gen starting from momentary voltage drops.

The pick up to transfer back may be over 208, since 208 (anything below 220) is never the sign of a stable 240 volt system.

 

[mdfriday]

Check the pick up and drop out voltages, are they adjustable? The drop out voltage might be at 200 volts so 208 satisfies the requirement, hence no transfer. Low drop out settings are often to prevent nuisance gen starting from momentary voltage drops.

The pick up to transfer back may be over 208, since 208 (anything below 220) is never the sign of a stable 240 volt system.

If the voltage is the issue, and it cannot be adjusted, I am assuming I can just get a 208V - 120/240 control transformer and install it in the ATS pre solenoid, switch, relay, etc....????

 

[Meadow]

If the voltage is the issue, and it cannot be adjusted, I am assuming I can just get a 208V - 120/240 control transformer and install it in the ATS pre solenoid, switch, relay, etc....????

Yes. As long as the va is at or above the old transformer.


However, contact the ATS maker and see if they have an alternative just in case they do. If the transfer switch is a non resi model it will have adjustable perimeters, some resi do as well.

 

[mdfriday]

Yes. As long as the va is at or above the old transformer.


However, contact the ATS maker and see if they have an alternative just in case they do. If the transfer switch is a non resi model it will have adjustable perimeters, some resi do as well.

Even though a business purchased this, they purchased a resi unit.....I was against it and advised them to go a different route.....

 

[Roger123]

I had same problem with a Generac Uint with 120/240 volt supply. Found out that the genny supply coil was bad from the factory and that Generac has been having the same problem with other units. I don't think it is the sensing unit, N1 & N2 wires.

 

[RandyM]

If all else fails you could run a 480 circuit to a 480 to120/240 transformer to feed an 100 amp single phase sub panel.

 

[Meadow]

Even though a business purchased this, they purchased a resi unit.....I was against it and advised them to go a different route.....

Customer is always right, part that's frequently left out is only when they know what they are buying.

But, like the other posts mention test that the solenoids transfer back and fourth if you can.


If all else fails order an ASKO transfer switch. That is as long as the gen is 2 wire start.

Do you have a model number for the ATS?, just to look over the wiring diagram/set points.

 

[rewire]

maybe it is time to hand it off to a generac warranty service provider.

 

[Meadow]

maybe it is time to hand it off to a generac warranty service provider.

Who will probably blame the customer for "improper system condition". Regardless though I would see what they say.

 

[k.gelectrical]

ats 16 circuit transfer 50 amp

that model ats was recalled they are sending all the dealer the repair kit to fix that problem.

 

[nrp3]

Let me see if the evolution controller can be adjusted for drop out and pick up voltages. If not, I would think a step up transformer from 208 to 240v feeding N1/N2 (sense wires) would cure this. I have wondered about this myself as I have started installing 20kw units on some community room buildings for the housing units I work on. We had this discussion about using the residential grade units.

After that it could be a micro switch, bad transfer relay, or transfer coil.

There is a bulletin for this if it is found to be a bad transfer mechansim. Looks like it gets replaced with a traditional 100a mechanism. Have a warranty guy look at it.

 

[nrp3]

Return to utility occurs after 15 seconds of at least 75% of nominal. So assuming 240v is nominal 240x.75=180. Sounds like more of a mechanism problem. Looks from the book the voltage to start and transfer is 65% for 10 seconds and is adjustable on evolution units.