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Earth Leakage Clamp Meter - Great Tool!

Foffer
Maybe I'm behind the times and you've all known about these for years!


I've just started using a Megger DCM305E clamp meter which can measure current from 0.001mA to 100A, meaning that its prime application is measuring earth leakage.  Clamping around both meter tails together or around the cores of a specially made extension lead test rig quickly helps track down the offending item causing RCD/RCBO tripping.  This tool speeds up fault finding a great deal and causes minimum disruption in a working environment.


Just wanted to bring this tool to the attention of anyone who like me hadn't heard of it before!


Also, I don't know if there are similar tools made by other manufacturers.....
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  • 0
    Most TVs prior to the introduction of SCART sockets had a mains derived power that made the chassis live or neutral;  or if it was a Phillips, then live on negative half cycles, and neutral on the positive cycles, as the rectifier was a bridge.


    In all cases that  I recall the antenna isolation was 1000 pf or so of capacitance twice, being in the centre and another one in the braid of the coax. Problem is the set would keep working perfectly even if the capacitor had failed, but would then be very 'tingly' indeed, saw that at least a couple of times. These were the sets where pulling the plastic volume know off revealed a live brass shaft, and in one design I cannot remember the make,  under some unfortunate condition the metal speaker grill could become live, and there was a stock fix to over sleeve the speaker wires.


    There were audio transformers with mains thickness insulation for headphones in the 1970s, but I do not recall seeing an RF transformer antenna isolation until after the SCART era, by which time the PSU was fully isolating and a generally more standardized approach was being adopted and  CE marking and safety tests followed a bit later.
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  • 0
    Most TVs prior to the introduction of SCART sockets had a mains derived power that made the chassis live or neutral;  or if it was a Phillips, then live on negative half cycles, and neutral on the positive cycles, as the rectifier was a bridge.


    In all cases that  I recall the antenna isolation was 1000 pf or so of capacitance twice, being in the centre and another one in the braid of the coax. Problem is the set would keep working perfectly even if the capacitor had failed, but would then be very 'tingly' indeed, saw that at least a couple of times. These were the sets where pulling the plastic volume know off revealed a live brass shaft, and in one design I cannot remember the make,  under some unfortunate condition the metal speaker grill could become live, and there was a stock fix to over sleeve the speaker wires.


    There were audio transformers with mains thickness insulation for headphones in the 1970s, but I do not recall seeing an RF transformer antenna isolation until after the SCART era, by which time the PSU was fully isolating and a generally more standardized approach was being adopted and  CE marking and safety tests followed a bit later.
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