Fuses burned out
Fuses burned out
(OP)
Hello friends,
At one industrial facility, there are some capacitors which include their tunning reactor (at 4th component) to compensate PF, they are located at medium voltage.
However, very oftenly the fuses of the "capacitor+ reactor circuit" are burn out, I mean, they are not blown, after some hours they are burned, even the outside!
We have already done some measurements, and harmonics levels are quite low, in voltage and current.
Has anybody experienced something similar?
Any ideas will be welcome!
Best Regards,
At one industrial facility, there are some capacitors which include their tunning reactor (at 4th component) to compensate PF, they are located at medium voltage.
However, very oftenly the fuses of the "capacitor+ reactor circuit" are burn out, I mean, they are not blown, after some hours they are burned, even the outside!
We have already done some measurements, and harmonics levels are quite low, in voltage and current.
Has anybody experienced something similar?
Any ideas will be welcome!
Best Regards,






RE: Fuses burned out
Can you post pictures?
Have done a thermographic scan when in operation?
Rafiq Bulsara
http://www.srengineersct.com
RE: Fuses burned out
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Fuses burned out
Too many times people experience a series of blown fuss and just keep replacing the fuses without inspecting the clips. The heat can weaken the pressure springs, which increases the contact resistance so the fuse starts heating up faster every time.
So at least inspect the fuse holders but if it were me, I would just do a prophylactic replacement now. Then you should try to determine why they kept blowing in the first place. My first suspicion would be resonance and/or high harmonics. Although you may think you have already eliminated that, is it possible that some piece of non-linear equipment, such as a VFD, comes on when you are not looking? Did you do a recorded analysis over time?.
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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RE: Fuses burned out
I thank your kind answers and comments!
The final customer has done some measurements over time, despite having some "inconsistencies", they do not show a significative amount of harmonics but, fuses keep burning.
We had previously done a resonance analysis and found the system prone to several resonance frequencies, however, even with installed relays we have taken the values of harmonic registered and nothing excessive.
I remember that even some capacitors have been replaced by the manufaturer and the problem continues.
If you had another clue or recommendation, please, let me know it.
RE: Fuses burned out
Rafiq Bulsara
http://www.srengineersct.com
RE: Fuses burned out
I thank your post!
Yes, I did read the previous posts, maybe I was wrong writing my last post because, it may be not correct at "this stage" of the conversation.
RE: Fuses burned out
old field guy
RE: Fuses burned out
Loose fuse holder clips.
Loose switch blade clips heating and conducting heat to the fuses.
Improper cable installation. I have seen installs with parallel feeds where one conduit contained "A" phase and part of "B" phase and the second conduit contained part of "B" phase and "C" phase. The unbalanced magnetic flux heated the conduits and the cables conducted the heat to the switch. The switch was destroyed several times by heat accelerated corrosion, and the fuses would fail from time to time.
Using the old "Renewable" fuses. These were bad news. Failures were common and burning of the fuse barrel was not uncommon. Use one-time fuses.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Fuses burned out
------------------------------------------------------------------------
If it is broken, fix it. If it isn't broken, I'll soon fix that.
RE: Fuses burned out
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Fuses burned out
I will talk to the responsible in order to perform some tests and in that way evaluate what you politely have recommended.
Regards,
RE: Fuses burned out
Let us know what you find. WE all learn much from the misery of others.
old field guy