fuses
fuses
(OP)
Good day
A number of fuse failures have being occuring on our plant. I have checked the tightness of the wires/connections. They seem to be in good condition. Properly rated fuses are being used. I have a concern that most of the failures are occuring on the supply side. What could I look at to resolve this problem. The fuses are housed in fuse holders.
Thanks in advance.
A number of fuse failures have being occuring on our plant. I have checked the tightness of the wires/connections. They seem to be in good condition. Properly rated fuses are being used. I have a concern that most of the failures are occuring on the supply side. What could I look at to resolve this problem. The fuses are housed in fuse holders.
Thanks in advance.





RE: fuses
Are you talking about fuses for machinery or fuses for lighting? Or both?
Are the fuses hot in normal operation? Or are they just normally warm?
Is your voltage normal and stable?
Has any new equipment been installed lately? (Frequency inverters and thyristor controllers generate harmonics that tend to be shorted out by power factor compensation capacitors and thus overload fuses for flourescent lights with capacitors attached in parallel).
If you have a current transducer and a scope available then check the current waveforms in the fuses that fail. If you have waveforms that deviate a lot from a sine wave then have to find the cause for it and find alternative solutions.
Please keep us informed how you solve this problem.
RE: fuses
the fuses are warm in normal operation. voltage is a 380V supply.
no equipment has been installed
I am currently monitoring the problem
RE: fuses
motors is frequently a mechanical problem that
temporarily overloads the motor.
Connect a digital O Scope with a current clamp to the
circuit and set the trigger for one shot and
the threshold 30% higher than the fuse rating and
you might capture a waveform indicating a
temporary mechanical problem.
Use low bandwidth current probe to avoid triggering
the scope with noise.
Rodar
RE: fuses
RE: fuses
Added resistance, lower voltage, higher current,
Then more heat from higher current, lower voltage, higher current, ad infinitum.
Check motor contactor also, if weak then current increases.
Check fuse size. NEC range is 125% - 250%, but for inductive loads such as pump motors you do not want to be at the lower end of that range but rather try to be at 150% minimum, preferably 175% or higher if motor is started frequently with short time between starts. OK, so then some will automatically ask why increase fuse size, is that not dangerous? If original fuse was sized too close and was always on the very edge, then slight aging problems in electrical supply and equipment could push you over the edge making it appear that some problem developed. If anyone remembers, ask them if this fuse ever required replacement. If the fuse was always on the edge I bet they had to replace the fuse once in a while but not too often.
Did the operation of the pump change? Before pump may have been started infrequently but now starts more often. Did flow rate of pump increase? Was grade of oil changes to a heavier type?
PUMPDESIGNER
RE: fuses
RE: fuses
Bung
Life is non-linear...