Halving 220V Output Voltage: Investigating the Problem

[sbsapre]

Dear All,

In our plant , we have an 20 KVA UPS with three phase , 440 Volts , 50 HZ input . The output is single phase 220 Volts outputted from Isolation transformer.
I find it strange though output voltage between two terminal of isolation transformer is 220 Volts , when measured with respect to ground , it is 110 Volts.
I want to understand how the output voltage is halved when measured with respect to ground.
Another problem whenever output voltage is connected to load which is normally fed by another 20 KVA UPS having 3 phase , 4 wire , 440 volts output , the single phase UPS fails.
We have taken precaution of connecting two terminals of 220 KVA single phase UPS to one phase and ground of the load terminals which are normally fed by UPS having three phase output.
I shall appreciate valuable inputs from members.
Regards,

S.B. SAPRE

 

[NoTime]

Dear All,

I find it strange though output voltage between two terminal of isolation transformer is 220 Volts , when measured with respect to ground , it is 110 Volts.
I want to understand how the output voltage is halved when measured with respect to ground.

Most likely it is a center tap transformer. With the tap connected to ground.

 

[ravenprp]

Dear S.B. SAPRE,

Thank you for bringing this issue to our attention. It is indeed strange that the output voltage of your 20 KVA UPS is halved when measured with respect to ground. There could be several reasons for this, and I suggest we investigate further to determine the root cause of the problem.

One possibility could be an issue with the isolation transformer itself. It is possible that there is a faulty connection or a damaged component within the transformer that is causing the voltage drop when measured with respect to ground. Another possibility could be an issue with the grounding system in your plant. If the grounding is not properly set up, it could affect the voltage readings and potentially cause the UPS to fail when connected to a load.

I recommend conducting a thorough inspection of the isolation transformer and its components to check for any signs of damage or malfunction. It would also be beneficial to review the grounding system and ensure it is properly installed and functioning correctly. If necessary, consulting a professional electrician or engineer could help in identifying and resolving the issue.

Thank you for seeking input from our members. I'm sure others in our community may have additional insights or suggestions to offer. Let's work together to troubleshoot and resolve this issue.