Multimeter acts funny after measuring transformer secondary resistance

[TopLoser]

Has anybody ever had a multimeter act 'odd' after measuring the resistance of a transformer secondary winding? Only temporary, the fault resets when switching to another measurement function. There must be some high voltage surge after the probes are disconnected, maybe enough to upset the input circuit?

Yes I have asked for the test to be repeated using just a 220 ohm resistor, but I'm interested in what people might have experienced.

[Monkeh]

Can't say I have.. although it's not unusual for autoranging to go absolutely bonkers when presented with windings.

[macboy]

I think you are right about the high voltage surge. Think about it: the meter measures resistance by putting a constant current through the DUT (transformer winding in this case) and measuring the voltage. When you remove the connection to the transformer, the current is interrupted suddenly. A transformer winding is a big inductor, and what happens when you change current quickly in an inductor?

Try putting a snubber across the transformer winding, say a 10 ohm resistor in series with a 10 nF cap. This should not affect resistance readings since the cap blocks DC. Measure again. Do you get the same strange behavior from the meter? Probably not.

[albert22]

It happened to my fluke. But only when measuring windings not afterwards. Try disabling the auto range and selecting a suitable range for the measurement.

[mushroom]

Same problem while measuring (not after) only in autorange mode with a UT61E. The aurorange algorithm does not understand the inductive load, and turns the DUT + DMM into an oscillator (nice trace on the oscope).

Could your DMM firmware crash ?