Incoming Fluctuating Power Supply

Is the voltage fluctuation present on all the three phases? What is the level of change in voltage?

There is SO much you haven't told us!!!!!!!!!!!!!!!!!

Where are you?

Have you talked to your power supplier?

WHAT HAVE YOU DONE?

Maybe hiring a local electrician would be the best thing to do.

This is the best free advice you will get all day!!!

Change your name until you know what to ask and/or do.

Hi I know what to do, may be you could come out in the open and identify your self.

Why did you leave an auto-tap changer in manual position?.

Good question.

_{Sadly, there isn't a Good Question button, only a Good Answer one.}

See Mr.Electrotech, if the output voltage of the transformer is low than the rated we can increase by changing the tap position but here u have mentioned its fluctuating, u have to tell what is the fluctuation level and normally fluctuations may occur incoming side only due to variable transsmission & distribution losses, commonly it may exists for few minutes. please find out incoming side also(12kv) fluctuation is there or only in outgoing of the transformer (480v). if its 12kv side u have contact ur power supply provider, but if exits in 480V side we have to cross check the transformer load side in ideal position (ie with out load), in ideal position of the transformer fluctuation is not there means u have to check ur loads due to over load also fluctuations will occur.

Thank for your answer, I know what i have to do because it is coming from the incoming I know that I have to put the Auto tapchanger on auto so it could compensate when the voltage fluctuate.

What revolutionary thinking...

Has there been a reduction in the fluctuations since you have allowed the tap changer to do its job?

I really can't understand why you had it running in manual, they are not an inexpensive piece of equipment and are fitted for a reason.

The size of the fluctuations is of interest. Were it inside +/- 10% on the LV side, don't worry about it.