Automatic Transfer Switch Problem

danilorayob

Hello,

I have an ONAN OTUDD100-4/1201C (Serial j810595543) automatic transfer swicth for a 30 KW 120/240 V 3PH Generator. The control panel is also 3PH. Nonetheless, the power company electric supply is 120/240V 1 PH 3 Wires. My issue is:

1. When we connect the above-mentioned current we will lack phase 3 and the transfer switch will interpret that there are only two phases and will, by default, start the emergency generator. Thus, I would like to know how to prevent this from happening.

Danilo

Fish4Fun

Danilo,

Welcome to PF!

If you currently have a 240V 1 phase supply, why would you attempt to have a 3 phase back-up generator? This is a nightmare! "Supply is 120V/240V 1 PH 3 Wires" is standard single phase. There is NO good way to connect a 3 phase generator to your existing panel. Even if you did, you would need some way of balancing the load, and that is far more complicated than simply purchasing a 30kW single phase generator. I am not certain who decided you should purchase a 3 phase generator, but you should make them take it back, it is completely unsuited for your needs.

Fish

danilorayob

Dear Fish4fun,

I appreciate your concern and advice. Let me give you some background on the case. I am Nicaraguan and Nicaragua is a kind of wonderland where people buy equipment without knowing if they suit their needs. The problem is that the 30 KW 3PH Generator is already bought, is old and cannot be returned. Thus, I have to work with it imperatively. But this is the least of my problems because I can make the generator work as a 120/240 V 1 PH via a double delta or zigzag combination for 1 PH for the 12 lines coming out of the generator.

My real problem is the ONAN OTUDD100-4/1201C (Serial j810595543) automatic transfer switch which is 3PH and will interpret that 1 phase has failed and thus will not carry out its tranference function.

I appreciate your kind advice,

Danilo

dlgoff

Can you purchase a 1 phase transfer switch? Other than that, I think you might not have any other options.