UPS and Step down transformer issue


New Member
Jul 31, 2009
I am using Maxine brand 220v to 110v step down 2k transformer and stabilizer to power all of my 120v gadgets.

Recently I have installed 800VA UPS and when the UPS kicks in, the output voltage of the transformer goes from 110v to 150v. I have measured the EB input 235 and the UPS input 250v. The installer says all the UPS will start with 260~270v and as the load is added the voltage drops. I have seen the sales guy of the step down unit to demonstrate that it would give constant output while changing the input voltage between 190 and 270v. But when it is connected to the UPS it is not doing it.

Also, the UPS produces noise when the transformer is connected. According to UPS guy I should not be connecting any stabilizer to the UPS load.

Since the output voltage is way too high, my power conditioner shuts off. Is there a way to get around this issue?

Thanks a lot for any suggestions.
There is a severe mismatch between the UPS and step down transformer capacities. You cannot connect a 2KV unit to a 800VA unit. Your UPS will not be able to handle the load and will behave erratically. The UPS must, at the minimum have the same capacity as the step down transformer, preferably more.

In any case, 800VA UPSs generally have quasi sine wave outputs and cannot be used with audio video equipment.

These have been discussed a number of times across the forum. Since you have joined recently, please search the forum for discussions on power conditioning and use of UPS.

APC smart ups are pure sine wave ups but then they are also expensive and in your case a 2kva model would cost more then 20k so the point is that this is not a cost effective solution in comparison to a servo of the same capacity.
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