Electronics > Beginners
Brymen BM235 10A fuse silently destroyed by a switched off UPS leakage current..
hgg:
"In other words, devices are meant to be plugged into it when it is switched on, not when it is switched off"
I understand. The UPS has a switch off though and I have not read anywhere that you should not switch it off
with the devices plugged in.
"(Under no circumstances should you ever connect a DMM to a power output socket while the DMM is set to measure current.)"
Maybe you did not understand.
I connected the DMM between live and ground to see if there was any leakage current.
Is there a capacitor connected between live and ground inside the UPS?
Cnoob:
--- Quote ---Is there a capacitor connected between live and ground inside the UPS?
--- End quote ---
Without seeing the circuit we don't know.
As you said it's cheap, one cost cutting exercise is the use of autotransformers.
And you found out the hard way not to use a meter too short out the Live to Earth.
hgg:
I guess you are both right.
I've shorted live to earth... :palm:
hgg:
I did not expect to be any current though with the UPS switched off.
That fuse is a beast. I had a very hard time breaking it open with pliers!
Maybe that is why it was so quite. The only thing I can see is some
black grains.
Is there any remote possibility that this would be genuine ?
https://www.ebay.com/itm/Bussmann-DMM-B-11A-1000V-DMM-11A-Multimeter-Fuse-for-Fluke-87-V-88-V-287-289-179/261536107575
Cnoob:
I suspect those ebay fuses are too cheap But I will leave it up to you.
If you want to measure earth leakage put the meter inline with earth wire or use a clamp meter.
Rule of thumb (but not always) measure current on the low side/return.
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