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Deleted member 105166
I have a Megger MFT1741 with current clamp, also a Fluke 117.
As the MFT can't record min/max, I'm using the current clamp with the Fluke multimeter, following Megger's instructions and understanding the 1000:1 step down ratio.
Just taking some basic readings on known values, the results are well outside what I'd expect to see.
For example, a line load of 8.29A on the MFT translates as 14.4V on the DMM
An 0.8mA earth leakage on the MFT shows as 2.3mV on the DMM
As the DMM is true RMS, I understand peak voltage being 1.41 x the RMS, however the measurements I'm achieving are significantly outside any adjustment to take this into account.
All equipment is recently calibrated and works very predictably on its own.
The current clamp also hums when used with the Fluke DMM if clamping a load over a few A.
It does not hum when used with the MFT, irrespective of load size.
Any thoughts/ideas welcome (other than "why did you buy that over priced huge I-clamp instead of the much more useful and compact Megger DCM305 clamp?"...which I've asked myself many times...
As the MFT can't record min/max, I'm using the current clamp with the Fluke multimeter, following Megger's instructions and understanding the 1000:1 step down ratio.
Just taking some basic readings on known values, the results are well outside what I'd expect to see.
For example, a line load of 8.29A on the MFT translates as 14.4V on the DMM
An 0.8mA earth leakage on the MFT shows as 2.3mV on the DMM
As the DMM is true RMS, I understand peak voltage being 1.41 x the RMS, however the measurements I'm achieving are significantly outside any adjustment to take this into account.
All equipment is recently calibrated and works very predictably on its own.
The current clamp also hums when used with the Fluke DMM if clamping a load over a few A.
It does not hum when used with the MFT, irrespective of load size.
Any thoughts/ideas welcome (other than "why did you buy that over priced huge I-clamp instead of the much more useful and compact Megger DCM305 clamp?"...which I've asked myself many times...