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I'm planning to move to a different place and the voltage there is 240V 50Hz. Currently, most of my appliances are 115V except for few 220V devices. Sold most of the high power 115V devices. I do have a few small office devices and a UPS which I would like to take it with me. I know by using an auto stabiliser it can be solved. But if I were to use a regular 1000W step-down transformer, the frequency would be different right? I'm not planning to use any inductive devices just the UPS. Will it heat up the device? or damage it? Thanks in advance everyone. Edit: I've read people specifically mention about inductive loads heating and electronic clocks running slower but didn't come across anyone mentioning about UPS or power electronic devices much. In the figure, I've used only the transformer not the stabiliser like my original setup I'm planning to use. Circuit diagram

automatic stabiliser servo type

step down transformer

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    \$\begingroup\$ Draw a diagram of what you intend to do. \$\endgroup\$ – winny Jun 11 '17 at 11:43
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    \$\begingroup\$ And explain what an "auto-stabiliser" is. Links are good. \$\endgroup\$ – Transistor Jun 11 '17 at 11:55
  • \$\begingroup\$ What does it tell you on the box about operating at a lower frequency? \$\endgroup\$ – Andy aka Jun 11 '17 at 12:18
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    \$\begingroup\$ Depends on the UPS and the equipment. My UPS will work off 50 or 60Hz and output the same frequency as it gets from the input. \$\endgroup\$ – Finbarr Jun 11 '17 at 12:51
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    \$\begingroup\$ You have drawn the transformer incorrectly. Connect the lower pole of both primary and secondary, and your drawing will be more accurate. The point being, autotransformers are not isolation transformers. \$\endgroup\$ – Harper Jun 11 '17 at 15:17
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I know by using an auto stabiliser it can be solved.

The Yomin device pictured says "servo motor control voltage regulator". That suggests that it has something like a variac (variable auto-transformer) driven by a motor.

enter image description here

Figure 1. Servo-motor controlled variac.

This is probably overkill if you are moving to a location with a stable power supply with normal +/-10% tolerance. An adequately sized auto-transformer as shown in your second photo would be adequate. A related question, Step down transformer voltage between neutral and ground, came up today.

But if I were to use a regular 1000W step-down transformer, the frequency would be different right?

Correct. But it will be for the Yomin device too, judging by its front cover.

I'm not planning to use any inductive devices just the UPS. Will it heat up the device? or damage it?

It depends. If it were my equipment I would open it up and assess the situation as follows:

  1. Does it have a mains transformer running the UPS charger? If so there could be a bit of bother. Generally, transformers and motors will run hotter on 50 Hz (due to lamination thickness and eddy-currents).
  2. If it looks as though it is running a switched mode power-supply to charge the battery you might be OK. The problem in this instance is that the internal high-voltage DC derived from the mains only gets topped up every 10 ms half-cycle instead of every 8.33 ms on 60 Hz. The resulting additional voltage droop between half-cycles may cause the device to malfunction. On the other hand, it may work fine. The manufacturer may have designed it to work on 50/60 Hz but only tested it on 60.

... but didn't come across anyone mentioning about UPS or power electronic devices much.

Most aren't sensitive as they rectify to DC internally.

In the figure, I've used only the transformer not the stabiliser like my original setup I'm planning to use.

The figure is fine other than we would normally draw power flow from left to right. i.e., Power source on the left.

See http://www.armory.com/~stacey/frequency-50.html for more information. (I gave it a very quick scan and it looks OK.)

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  • \$\begingroup\$ Thanks mate. I checked the manual and it says the acceptable frequency range is 56-63Hz.Not sure how much of a difference it would make. Hope it wouldn't blow up. The unit is APC UPS BK500MC. \$\endgroup\$ – The_Vintage_Collector Jun 11 '17 at 18:41
  • \$\begingroup\$ The fact that they have specified a frequency range that doesn't extend down to 50 Hz suggests that you shouldn't use this in 50 Hz land. \$\endgroup\$ – Transistor Jun 11 '17 at 19:15
  • \$\begingroup\$ I've contacted APC and waiting for input from their side. Frequency converters are too expensive. I'll junk it if there is no option. But what makes me still think is doesn't a UPS function like a normal charger while power is present and run as an inverter in case of power failure. What could possibly fail if the frequency is wrong? Also there are two transformers. A very Large one for inverter function possibly and a small one(like the one found in computer PSU) on the mainboard for charging the battery maybe. \$\endgroup\$ – The_Vintage_Collector Jun 12 '17 at 11:59
  • \$\begingroup\$ Send a link to a block diagram of the APC UPS. See if mains goes straight through when on or through the UPS's inverter. Consider what happens when the mains fails - load switches from 50 to 60 Hz. That might not be a problem but what if the UPS is trying to synchronise its output with the mains for bumpless switch-over? It can't. It's could probably only do that for 56 to 63 Hz. \$\endgroup\$ – Transistor Jun 12 '17 at 12:34

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