Unknown Variable_Resistor

Thread Starter

mortenlund

Joined Mar 20, 2020
17
Hi all

I have gotten this variable resistor or very large potentiometer. It looks like wire wound with some resistive metal wire of maybe 0.25 - 0.5 mm2 (AWG 24 - 20) exposed in front where a rotating copper plate can conduct. The other sides are covered in some isolating material. It is all on a ceramic ring. Please see attached images.

Does anybody know this product or something similar?

Even not knowing this specific product, I would greatly appreciate any thoughts on its limits in both voltage and current. Any qualified guess is welcome.

Thanks in advance.

Morten
Denmark
 

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Pyrex

Joined Feb 16, 2022
247
Hi, Morten
it seems to me, P250 means the power rating- 250W.
If so, voltage can be found easily : U=sqrt(P*R)= sqrt(250*2000)=707 Volt
Amperage can be found in the same way: I=sqrt(P/R)= 0.35 A
 

Thread Starter

mortenlund

Joined Mar 20, 2020
17
Thank you all. I greatly appreciate your answers. It is a throw out from the electrician company I work in.
Yes it must have been purchased for mains equipment testing - 230 or 400 V.

I plan on using it for eg. testing unknown transformers, using pin 1 for L and pin 3 for N. Then having a variable output between 0 and 230 V. Of course taking into consideration the high ampere that would be possible if testing a low ohm device. Will build a series coupled 0.25 A circuit breaker in to it and attach a thermostat with auto reset on its top side. Then building it into a cabinet with voltmeter and some more.

Just a follow up question, is this setup not much like a vario transformer and well suited for testing eg. unlabeled transformers?

Again thanks for all inputs.

Morten
 
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