ReplyWe had one doing that and it was a setting on the main breaker feeding the chiller. You may have to tweek them a little with the help of someone who knows what they should be let at.
Professional Member
Got a call today from a customer with a 500 ton CVHE. Engineering has had to reset the main twice in the past few weeks and said it happened again last night at midnight. Go out today and meg the motor 2200+, start the machine and check everything out, no problems. Briefly noticed a low oil pressure and quickly went away without producing a diagnostic. It only did this once but has me curious. Put a fluke current trend on today so will monitor that. Any thoughts would be appreciated.
Professional Member
We had one doing that and it was a setting on the main breaker feeding the chiller. You may have to tweek them a little with the help of someone who knows what they should be let at.
Professional Member*
You could pull the breaker and have it tested. I would not adjust the settings unless you absolutely know what you are doing.
If you adjust settings you could be upsetting the coordination of fault protection in the building.
Then if you have a actual fault with chiller motor, instead of tripping the breaker in starter, you may trip the main to the building.
Depending on what they do in this building, you may not be very popular.
“If your work speaks for itself, don't interrupt.” ~Henry J. Kaiser
"Highly efficient equipment and LEED Bldgs are very expensive to maintain in order to keep that efficiency!" ~ Me
Regular Guest
When I had this problem, it was burnt contact points in breaker inside control panel.
Member
Have the breaker tested and eliminate a loose lug by checking all the connections. Had that happen before, now we recommend all high voltage and chiller eletrical panels be thermal scand. A hot connection shows up instantly.
Professional Member*
commloss
what generation machine do you have (UCP2, CH530) etc?
All points mentioned here are good. I know that the starer should take you out sooner, but could you have a loaded start condition? You are megged out good, I wonder if you have an issue with 1st stage guide vane open at start up. Maybe pull the suction cover oil return line and put a gauge on it and the evap at the same time at start up to see how close they are.
For giggles, wipe the terminal board real clean with contact cleaner on the off chance you are arcing there.
I remember a message out a while back on the blue light that in rare cases the U3 mod drove the guidevanes full open or enough open to cause issues like this.
r404a
Professional Member
UCP2. thanks for all the replies and all are good points. I did check for loaded start condition already and been thru the starter thoroughly. The only thing I havent done was the breaker check or adjustments which was mentioned here by a few guys. The breaker hasnt tripped in 2 days and the current trender is looking good.
Regular Guest
I,d be checking mechanical interlocks on motor switchgear
Regular Guest
I would start at the switchgear . I operate a powerplant on my night job and have 1500 ton CVH's .We have had a faulty main fuse cause something very similiar .
Professional Member
I would spotcheck the breaker with an infrared thermometer. Normal temps are around 85 degrees. Hot spots may be around 95-100 or more. A thermal image camera is the ticket.
It might get loud!
Regular Guest
Surge maybe , if switchgear good
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