Transformer Unbalance - Open CKT Voltages

When you say open circuit voltage, I assume the electrodes are disconnected??

Is the voltage measurement to ground reference?

Is there a heavy current unbalance when the transformer is in service?

Hi,

Open Circuit Volatge means when the transformer is supplied with a voltage on the HV or LV side ( 1:1) Transformer, then Open Circuit means the transformer is under no load.

Voltage measurement shall be Phase to Phase, Phase to neutral.

Current Unbalance shall be unbalance in load. The differntial relay will operate during current unblance as this protection will be based on Unbalance current.

N.Suresh

Is the incoming line voltage balanced?

If everything looks good, then it sounds like your transformer has shorted turns. I would recommend taking out of service and perform..

1- winding resistance

2- TTR Transformer Turns Ration

3- Power Factor Test if available

Then compare against factory tests..

Hi,

If incoming line voltage itself is low/unbalanced then it shall be adjsuted in the sending end substation by balcning the load and the rasing the volatge. Raising/ lowering the voltage shall be done by adjusting the Tap cahnger in th trafo.

Alterantively the Voltage in the Bus can be improved by by providing Bus capacitor bank.

N.Suresh