We got a bit of snow today. Not much by anyone's standards (about an inch or two) but around here it's a big deal. Schools closed and everything. Ya I know :laughing: Anyway it was also pretty windy so snow was blasting around sideways and stuff.
The fish plant maintenance guy called me in a panic and said their main dock hoist stopped working and they're trying to offload a boat. So I pulled out of the job I was on and went down there.
The dock hoist is a hydraulic unit. To turn it on they have to make sure the E-stop is off and then hit the "On" switch on the control panel. Inside, there's a starter for the hydraulic pump motor. Then a transformer, some relays, etc for the hoist up/down controls and whatnot.
When I got there I found the control transformer fuses were blown on the primary (480) side. Secondary fuse was fine. Started testing the control circuit for any faults. Found the E-stop button was all crudded up and a couple wire strands were hanging out and contacting the metal enclosure, so I fixed that and the fault went away. Not sure why it blew the primary fuses instead of the secondary but they're probably sized wrong or something. Fuse labels were all worn out. Felt confident, threw some new transformer fuses in, closed it all back up, and fired it up. Ran fine. Left, went back to other job.
An hour later I got a call back saying it stopped working again. Dammit! Got back and found that someone (probably the maintenance guy) had gotten back into the control panel, which is a stainless enclosure mounted outside, for who the hell knows why. Well he didn't latch it shut all the way and a bunch of snow blew in there and eventually started melting all over the terminal blocks. Shorted out a bunch of stuff. So, replaced a few terminal blocks, blew the remaining snow out, and sat there with a heat gun for a few minutes. Still working fine.
I guess snow in enclosures is like a time bomb.
The fish plant maintenance guy called me in a panic and said their main dock hoist stopped working and they're trying to offload a boat. So I pulled out of the job I was on and went down there.
The dock hoist is a hydraulic unit. To turn it on they have to make sure the E-stop is off and then hit the "On" switch on the control panel. Inside, there's a starter for the hydraulic pump motor. Then a transformer, some relays, etc for the hoist up/down controls and whatnot.
When I got there I found the control transformer fuses were blown on the primary (480) side. Secondary fuse was fine. Started testing the control circuit for any faults. Found the E-stop button was all crudded up and a couple wire strands were hanging out and contacting the metal enclosure, so I fixed that and the fault went away. Not sure why it blew the primary fuses instead of the secondary but they're probably sized wrong or something. Fuse labels were all worn out. Felt confident, threw some new transformer fuses in, closed it all back up, and fired it up. Ran fine. Left, went back to other job.
An hour later I got a call back saying it stopped working again. Dammit! Got back and found that someone (probably the maintenance guy) had gotten back into the control panel, which is a stainless enclosure mounted outside, for who the hell knows why. Well he didn't latch it shut all the way and a bunch of snow blew in there and eventually started melting all over the terminal blocks. Shorted out a bunch of stuff. So, replaced a few terminal blocks, blew the remaining snow out, and sat there with a heat gun for a few minutes. Still working fine.
I guess snow in enclosures is like a time bomb.
