Generator Signal Voltage Source

[Duncan8943]

I've got one generator and two automatic transfer switches installed in a duplex. A 240 VAC signal is supplied to the generator which maintains the battery, but more importantly turns the generator on when the 240 VAC drops out. Each duplex is fed from the utility which goes through each utility meter and service disconnect on the exterior of the building. Where would you tie the 240VAC signal in and why? If you tie it in downstream of the disconnect for either side, then someone could easily think that they killed the power to the duplex and within a couple of minutes there would be power on the circuits.

 

[electrofelon]

funny you should ask, I was just working on a generator hookup today. I would think the "utility sense" should connect in the transfer switch, at least thats the way it was on this setup (generac). In the transfer switch are two terminals protected by 5 amp fuses and they have 240 volts between them. Check you transfer switch.

 

[Duncan8943]

Generator Control Signal

Generator Control Signal

There are fused utility connections in the generator automatic transfer switch which are normally used to send the signal to the generator. Rather than use these, I connected a 2A fuse block between the meter and disconnect. This was tied to the utility connection of the generator. This way if someone intentionally threw the disconnect to drop out the power going to either side of the duplex--the generator wouldn't start up. I am assuming that the either meter won't be pulled for non payment of a bill.

 

[macmikeman]

The circuit for maintaining the utility sense circuit must be fed from the panel that the switched loads are coming from. (usually that is the load center built into the auto transfer switch). There is an "off" switch built into the generators themselves, as well as the main breaker at each generator that can be used to prevent generator startup and backfeed when doing routine tests where the main utility power is shut off, but you do not want the generator to startup during that period.

 

[dicklaxt]

There could be different scenarios I guess but wouldn't the Generator spec sheet dictate the normal sequence of operation that the Gen was tested and listed for,is any deviation allowed:?

Is the sensor signal a dry contact closure/opening or is it actually switching voltage to the generator control system network:?

dick

 

[hillbilly1]

You didn't mention what brand of generator this was, but judging from what you have said, it is a Generac unit. They have several different control schemes depending on the model and size. Yours sounds like the one that uses the generator to control the transfer switch, not the other way around, unlike most manufactures. This causes issues when you have multiple transfer switches and power sources. All you can do without creating a complicated control scheme, is to use one of the units as the master, and the second as the slave. If power is lost at the slave (which would be unlikely, because there probably feed from the same transformer), the generator would not start. On the second transfer switch, you would only connect the DC control from the generator. The utility sense and charger circuits from this source would not be connected.

 

[hillbilly1]

By the way, how do you decide which unit of the duplex is going to pay for the power used to charge the battery and block heater if so equipped?

 

[Duncan8943]

The ATS units are Briggs and Stratton units which come with the whole house generators. The ATS has a board which will sense both the presence of utility and generator voltage. It will actuate based on the presence of one or the other. If both are present (during the 20 minute weekly test), nothing occurs. As far as deciding which duplex pays for the battery charging--one person is just luckier than the other...haha.

 

[hillbilly1]

Same thing as a Generac, sounds like you only need the utility voltage source from the same unit the charger feeds from, the other switch will only transfer if that unit also loses power.

 

[RUWired]

Not to jump in on your switching, but the Briggs and Straton ATS units have solid neutral bars in them, and by using only one generator between the two units, you have paralleld the neutral and ground together by means of the main bonding jumper in each unit. That would be a violation of 250.24(A)5. Having seperate generators or switched neutral ATS units would correct the problem.

 

[hillbilly1]

Not to jump in on your switching, but the Briggs and Straton ATS units have solid neutral bars in them, and by using only one generator between the two units, you have paralleld the neutral and ground together by means of the main bonding jumper in each unit. That would be a violation of 250.24(A)5. Having seperate generators or switched neutral ATS units would correct the problem.

You are so correct, we were so concentrating on the control issue, that the correct transfer switch was overlooked.

 

[pursery]

Transfer Switch vs Interlock

Transfer Switch vs Interlock

I recently purchased a portable generator and found a video on " Transfer Switch vs; Interlock ", and found the interlock idea to be very appealing. My home has a "Gould G1630MB1150" AKA "Siemens G1630MB1150" with a 150A main breaker. I am interested in finding an Interlock device to work with my panel. Is there a source that can help with this?