This is exactly what the title of the question from the reader Elena sounded like.
This is the 16th part of a series of publications - "Electrician Q&A". Who missed the past parts - as always, I remind you that in this and past publications (parts) I bring real questions from readers and my answers to them. I continue to do so in this part.
I quote the text of the question verbatim:
I connected the refrigerator LIEBHERR {CUN3033} through the PH-122 voltage relay. For about a week everything was fine, the mains voltage was within the upper limit, the factory setting was 250 volts, and the refrigerator worked. But from December 31 to this day, the relay shows 250-253 volts and the refrigerator is turned off for about 5 hours a day. And at night I don't know how it works at all. Please tell me if it is possible to set the upper limit on the 255 volt relay or is it unacceptable for the refrigerator? Is the relay defective? And why is there such a high voltage in the network in an apartment in Moscow, or is this the norm? Advise how to be? And yet, the relay heats up a little, but the case is warm, is this normal or not?
I gave Elena the following answer due to my knowledge and qualifications:
As far as I understand, you have installed the RN-122 voltage monitoring relay in the socket for connecting the refrigerator. There are many questions, but let's look at everything in order. If we consider the permissible operating limits, then in accordance with the passport data, the Umax control range is from 230 to 290 V. Therefore, yes, you can set the maximum voltage limit to more than 250 V.
The fact that you have set the maximum Umax limit of 250 V indicates the use of the factory settings (for voltage monitoring relay RN-122, the threshold for minimum voltage is 185 V, and for maximum 250 IN). To change the value of the maximum response threshold, you need to do the following:
- Press the Umax button on the control panel - this will open the maximum limit adjustment function;
- Then using the Umin key you can decrease the maximum threshold, and using the Umax function you can increase the maximum threshold;
- The data will be saved automatically after 5 seconds. After the transition, the display will show the current voltage in the circuit.
With regard to the rated voltage, in accordance with GOST 32144-2013, the maximum limit is 253 V (that is, + 10% to 230 V). But for many household appliances, this is too much. I recommend that you double-check it with a multimeter or voltmeter, if this is true, contact the management company with an official statement. Otherwise, it is possible that the relay is really defective and just needs to be replaced.
P.S. Link to some past parts - Part 15, Part 14, Part 13, Part 12, Part 11.
P.S. Dear readers of my channel, if you have your own version of the answer to this kind of typical questions - write in the comments. I and other readers will be happy to read them.