Cummins 20KW Generator low voltage wiring

[synchro]

The schematic for the RSS transfer switch shows that it doesn't have a K2 sense relay, and it sends the AC output of a step down transformer out on TB4-1 and TB4-2.
I would measure the AC voltage across those terminals with a meter to make sure you get a suitable relay for sensing the presence of utility power.
Apparently the RSS transfer switches are made for their GSAA, etc. generators.

 

[hillbilly1]

The schematic for the RSS transfer switch shows that it doesn't have a K2 sense relay, and it sends the AC output of a step down transformer out on TB4-1 and TB4-2.
I would measure the AC voltage across those terminals with a meter to make sure you get a suitable relay for sensing the presence of utility power.
Apparently the RSS transfer switches are made for their GSAA, etc. generators.

View attachment 2565026

Could just use a 240 volt relay across the utility to make the K2 output? Since the diagram is cut off, maybe it has a rectifier that sends 12 vdc to the generator control?

 

[synchro]

Since the diagram is cut off, maybe it has a rectifier that sends 12 vdc to the generator control?

The only other TB4 terminals are TB4-8, TB4-9, and TB4-10 that are labeled as "SPARE".
TB4-7 supplies a B+ output for battery charging, but there are no other outputs from the ATS that supply DC as far as I can tell.

 

[hillbilly1]

The only other TB4 terminals are TB4-8, TB4-9, and TB4-10 that are labeled as "SPARE".
TB4-7 supplies a B+ output for battery charging, but there are no other outputs from the ATS that supply DC as far as I can tell.

They must have had an ac relay in the generator to provide the start signal, I noticed the secondary is going out to the generator. The OP could put the relay at the generator if as you said, find the voltage that transformer puts out, and size the coil accordingly. Might be the simplest fix.

 

[MGRABHAM]

Hillbilly1,

Can you please re-confirm that this is the correct ATS Model# RA212S3 Part #A064G549 for the Cummins GenSet C20N6H RS20AE?

I did receive a TSR from Cummins Care folks today they also indicated that the RSS200-6869 ATS utility sense is different and I need to swap out the RSS200-6869 ATS with the RA212SE ATS model.

Thank you,
Marty

 

[LarryFine]

Did anyone ever check that the utility and generator power conductors were on the correct terminals?

 

[hillbilly1]

Hillbilly1,

Can you please re-confirm that this is the correct ATS Model# RA212S3 Part #A064G549 for the Cummins GenSet C20N6H RS20AE?

I did receive a TSR from Cummins Care folks today they also indicated that the RSS200-6869 ATS utility sense is different and I need to swap out the RSS200-6869 ATS with the RA212SE ATS model.

Thank you,
Marty

I think you can use the one you have, you just need a relay to convert the utility sense to a digital output. It just needs a contact closure to start the generator, the transfer signal is still controlled by the generator. If this is for you, that would be the way I would go. If it’s for a customer, then it would probably be better to change the switch. Generators are not that complicated, manufacturers just make it that way so you have to use their vendors.

 

[hillbilly1]

Did anyone ever check that the utility and generator power conductors were on the correct terminals?

I think his issue is, that model of transferswitch puts out voltage on the utility sense input instead of a contact closure, so the generator is not “seeing” utility loss. Because it takes both utility sense one and two to make the circuit, it didn’t conflict with the 12 volt dc control input, but just won’t work. The op needs a relay tied across the sense one and two outputs from the ts to convert to a digital input (contact closure)

 

[steve ardenas65@yahoo.com]

Here is the cheat sheet.

Hey Hillbilly. It my first Cummins ever and I’m having a hard time with the wire connections.
In Tb4 I am connecting a wire to 1,4 and 7 and the go to the wago dc block in the gen.
Where do I come off the t switch for the ac current to the two ac connection wago in the gen