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Discussion Starter · #1 ·
Well it happened. In February It will have been 2 years since I graduated trade school and started my life as an idustrial electricain. Tonight about 2 hours ago i got a called to one of air compressors. We had blown a fuse. The compressor is a 75hp monster. Turns out a blown fuse was the culprit. I put on my level 4 suit and pulled the 600 amp fuse, stuck the new one in and after making sure everyone was clear standing as far off to the side as i could flipped the switch.:censored::censored::censored: Man i never saw so many fireworks in my life. It arc blast blew a hole in the sid eof the peckerhead with flames shooting out a good 1 or so as the motor continued to try to turn. This wasn't the shocker to me. The shocker was the pecker head was about 5 foot from my face.

I am glad i had my gear on. We have an emergency compressor ming that i will be hooking up with in the hour. Stay safe out there guys you never know when Thantos will come looking for you.:thumbsup:
 

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Discussion Starter · #5 ·
Well the only thing that i could have done safer would have been to have one of those nonconductive switch sticks that the poco here use flip the switch instead of ding it by hand. I have all my protective gear on(class 4 suit with fr rated clothing under it rubber gloves, leather protectors and fr hood with the blast shield on). No one was hurt it just made for an exciting few minutes.
 

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Discussion Starter · #6 ·
Should've determined why the fuse blew in the first place before wantonly replacing it. I guess you know this though.
I tried to troubleshoot with out the fuse but the phase with the blown fuse was one of the phases for the control power. The starter for the compressor wasn't tripped nor was there any blown fuses with in the control cabinet. Wasn't any burnt wiring smell or anything else that we could think of.
 

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Discussion Starter · #9 · (Edited)
75 H.P. 600 amp? That's a wtf ?
The 600 amp fuse was the main disconnect coming off the transformer. The compressor it self has fuses between the main disco and the control box for the compressor. There was more then just the compressor motor in the "box". lso has 2 25 hp fan motors an air dryer and warmer.

We have a transformer just to power the 2 massive air compressors on the grounds. This disconnect feeds directly off the secondary of the transformer. From there it runs into the compressor control panel that feeds everything else.

Got the new compressor delivered and wired up. Plant back to normal.:thumbsup:
 

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Discussion Starter · #11 ·
What caused the short? Why didn't the new fuse just blow?
The fuse did blow but it took about 3 seconds or so to do it.
The only thing i could think for the short was the 75hp motor went bad. We have had a lot of rain the last 2 weeks and this compressor is outside. This is not the first time this compressor has done this. The motor in it is only 4 months old. However they compressor literally run 24/7 has the plant runs 24/7. IMHO The 2 compressors we have are to small for the plant and we either need a 3rd one so we can cycle between the 3 and give one a cool down period or we need bigger. However my opinion in the pecking order is about the bottom of the totem pole.
 

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Hey I don't know you but I am glad you are alright. Those types of accidents can be horrible :thumbsup:
 
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Estwing magic
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The fuse did blow but it took about 3 seconds or so to do it.
The only thing i could think for the short was the 75hp motor went bad. We have had a lot of rain the last 2 weeks and this compressor is outside. This is not the first time this compressor has done this. The motor in it is only 4 months old. However they compressor literally run 24/7 has the plant runs 24/7. IMHO The 2 compressors we have are to small for the plant and we either need a 3rd one so we can cycle between the 3 and give one a cool down period or we need bigger. However my opinion in the pecking order is about the bottom of the totem pole.
Still confused. Why didn't the new fuse blow the same as the original one? Three seconds seems odd.
 

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The fuse did blow but it took about 3 seconds or so to do it.
The only thing i could think for the short was the 75hp motor went bad. We have had a lot of rain the last 2 weeks and this compressor is outside. This is not the first time this compressor has done this. The motor in it is only 4 months old. However they compressor literally run 24/7 has the plant runs 24/7. IMHO The 2 compressors we have are to small for the plant and we either need a 3rd one so we can cycle between the 3 and give one a cool down period or we need bigger. However my opinion in the pecking order is about the bottom of the totem pole.
There are lots of air compressor motors out there that run 24/7.. Most have unloaders on them and will load/unload automatically, depending on the air demand. They had better last longer than 4 months...
 

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Still confused. Why didn't the new fuse blow the same as the original one? Three seconds seems odd.
It's possible that it did but nobody was there to witness it. Or more likely the old fuse was already running hot, being in the circuit 24/7, and the fault quickly brought it to fusing temp.
 

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I tried to troubleshoot with out the fuse but the phase with the blown fuse was one of the phases for the control power. The starter for the compressor wasn't tripped nor was there any blown fuses with in the control cabinet. Wasn't any burnt wiring smell or anything else that we could think of.
If the 600 Amp fuse blew before the main ones on the starter, you may have a bit of a coordination issue.. You may want to get the fuse info and do some checking.. Someone before you may have replaced a fuse with "what they had" and now it is out of whack...
 

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If the 600 Amp fuse blew before the main ones on the starter, you may have a bit of a coordination issue.. You may want to get the fuse info and do some checking.. Someone before you may have replaced a fuse with "what they had" and now it is out of whack...
This depends on whether the original fuse opened during run, or start.
 

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It's possible that it did but nobody was there to witness it. Or more likely the old fuse was already running hot, being in the circuit 24/7, and the fault quickly brought it to fusing temp.
I know what you're saying but, with a short circuit of this magnitude, a new fuse should react almost as fast as a fatigued fuse. The dots just aren't connecting here for me.
 
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