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OK, I am attempting to determine if this power pack, MRC 6200, is defective. The situation is, operating in mode 2 (rated 14 v, 27 va) potentiometer at half throttle ammeter on line reading .95 amps for approximately 1 hour the pack shuts down. Does this show the power pack to be defective or is this overloading the power pack?

I hope I am giving enough information for an answer.


A few comments:

We're right at the edge of a 'duty cycle' discussion.  The power pack may be rated at 27VA, but a secondary question is if the power pack was designed for that usage for hours on end, or just a typical length of running time, say 30 minutes?  In the old days, power packs were over-designed to provide reliability (think of the people who claim you can weld with a ZW), but newer power packs are likely not as over-designed due to efforts at containing costs.

Secondly, there might be issues with a weak thermal overload breaker too.  Don't forget that all of these parts have design tolerances and your transformer may have a thermal breaker out of tolerance or at the edge of being out of tolerance.


@Rayin"S" posted:

I am kind of a rookie, does what you are saying mean the power packs protection might shut it down at lower amperage?

Depending on how they regulate the power, a lower than maximum voltage, many power control circuits don't have the same current handling capability as they do at full throttle.

I don't do much with DC supplies, but take an electronic AC transformer, say the CW-80.  If you run it at 18 volts, you'll be able to get close to 80 VA, the current limit is 5 amps.  However, if you're running it at six volts at 5 amps, that's only 30VA before you trip the over-current circuit.

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