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Strange test results, generator supplied installation
Former Community Member
I did a bit of testing at an installation supplied by a generator and was confused by the test results. I had two testers with me: a megger loop tester and a MFT. The loop tester mainly refused to carry out the test due to the frequency being 51Hz but did give a result from a light switch of 0.9 ohms. The MFT gave a result of 20 ohms from the same light switch and similar (18 to 20 ohms) readings throughout. At the generator it gave a figure of 38.8 ohms. This doesn’t seem to make sense. I’ve done loop tests with both testers since arriving home and they seem to produce fairly similar results Could there be some feature of the way the generator operated that has led to this strange mix of results? Would the high supply frequency have an effect on the tester? HVe I done anything wrong when testing. I’d appreciate it if anyone can help.
. . . The loop tester mainly refused to carry out the test due to the frequency being 51Hz . . .
The high supply frequency is also worth a mention. Most mains powered clocks use the (usually steady) mains frequency to derive a “seconds” count to advance the display. If it really is 51Hz, then that will give you an additional 28.8 minutes a day on possibly all mains powered clocks. Is that acceptable?
. . . The loop tester mainly refused to carry out the test due to the frequency being 51Hz . . .
The high supply frequency is also worth a mention. Most mains powered clocks use the (usually steady) mains frequency to derive a “seconds” count to advance the display. If it really is 51Hz, then that will give you an additional 28.8 minutes a day on possibly all mains powered clocks. Is that acceptable?
