Typically, I don’t report about test equipment acquisition unless these are associated with repairs, but this time, I will make an exemption. I used to have an old isolation tester, but it has been playing up, and with the analog instrument, difficult to repair. So I checked about more recent instruments, mostly, to check electric installations and motors and similar, for isolation after repair. This requires a 1000 VDC test, because some isolation defects tend not to show up at low voltage.

After a quick search, I found an almost unbelievable offer, just about 25 EUR! Shipping included!

One week later, a badly packaged box arrived, in a plastic bag, but without major damage.

Inside, a handy soft case.

The instrument, the plastic is of good quality. The red plastic is a little hard so it will not absorb too much shock when you drop the device.

Immediately, I got some of the highest value resistors I have in stock, a Remix 1000 MOhm +-5 % resistor. This is good to 10 kV, so there is no problem or leakage when doing a 1000 V test (other resistors may be have voltage rating of 300 V or 500V).

At a first glace, very nice result. -2% within the tolerance of the part.

Checking the voltages, 1000 V is fairly accurate.

500 Volts, even better.

Some more deviation at 250 and 100 Volts.

The specifications are quite good. But eventually, the instrument is not used much to measure resistance, but to check for conduction when 1000 Volts are applied. Normally, it will either show >2000 MOhm, or a spark will fly and the high-voltage isolation test has failed.

For completeness, also checked a 200 Ohm, 0.1% resistor. 1.5% deviation is the specification of the MH15, and deviation found is 0.25%, very good.

All in all, a great instrument for the occasional user, and one more reason to not skip isolation resistance tests.