Automatic Transfer Switch Problem

In summary, Danilo is facing a problem with his ONAN OTUDD100-4/1201C automatic transfer switch, which is 3 phase and will interpret a 1 phase failure as a complete failure, causing the emergency generator to start. This is due to Danilo's power supply being 120/240V 1 phase, while the generator and transfer switch are 3 phase. Danilo is unable to return the generator and is looking for a way to make it work, but Fish advises that it would be easier to purchase a 30kW single phase generator or a 1 phase transfer switch.
  • #1
danilorayob
2
0
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
 
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  • #2
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
 
  • #3
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





Fish4Fun said:
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
 
  • #4
Can you purchase a 1 phase transfer switch? Other than that, I think you might not have any other options.
 

1. What is an automatic transfer switch?

An automatic transfer switch (ATS) is an electrical device that automatically switches the power source from the primary source to a backup source in the event of a power outage or other electrical issue. This ensures continuous power supply to critical systems or equipment.

2. How does an automatic transfer switch work?

An ATS works by monitoring the primary power source and the backup power source. When the primary source fails or drops below a certain voltage level, the ATS will automatically switch the load to the backup source. Once the primary source is restored, the ATS will switch the load back to the primary source.

3. What are the common problems with automatic transfer switches?

The most common problems with ATS include failure to transfer the load to the backup source, failure to transfer the load back to the primary source, and mechanical issues such as stuck or burnt contacts. Other issues can include faulty wiring, incorrect installation, and lack of maintenance.

4. How can I troubleshoot an automatic transfer switch problem?

If you are experiencing issues with your ATS, the first step is to check the power sources to ensure they are functioning properly. If the sources are working, then you can check the ATS for any visible damage or loose connections. It is also recommended to consult the manufacturer's manual for troubleshooting steps specific to your ATS model.

5. Can I repair an automatic transfer switch myself?

It is not recommended to attempt to repair an ATS yourself unless you have the proper training and experience. The internal components of an ATS can be dangerous and should only be handled by a licensed electrician or trained professional. It is best to contact a reputable electrical contractor for any repairs or maintenance on your ATS.

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