Results 1 to 10 of 10
09-24-2012, 10:37 PM #1
3 year old copeland scroll grounded..
all 3 terminals..this is a 3 phase system
ill check for acid but what causes all 3 to ground out?
this is a walkin refer with 3 evaporators..customer says
last evaporator never really put out cold air..
09-24-2012, 10:48 PM #2
Single phrasing can. Recommend a phase monitor and of course check for any problems once you have it running again.
09-25-2012, 12:40 AM #3
Obviously not your compressor but just a stock photo of a 3 phase stator. Notice how everything touches? A little fire on one winding will burn across everything and can short out the whole fam damly.
09-25-2012, 01:08 AM #4
O-tay..thanks..im not familure with a phase monitor..how do they work?
09-25-2012, 07:20 AM #5
Motors are either wound as delta(Δ)or wye(Y). In Delta wound, all three corners are connected to outside. In "Y" the three ends are, but the center knot is not.
As you can visualize, if any part of the winding touches the core, it will look like all 3 points are shorted, but in reality, you probably have a spot or two inside that shorted to the core.
More difficult ones are partial shorts that cause some turns to be skipped, therefore cause abnormal phase imbalance (i.e. coil #1 with 20% of turns bypassed due to a short will have overcurrent)
09-25-2012, 07:27 AM #6
09-25-2012, 08:41 AM #7
I think a phase monitor should be installed on all three phase motors, that would cause less failure in the field. Any thoughts?
09-25-2012, 07:34 PM #8
this system has one...and no acid in the sytem...BUT when i was packing up my tools one of the maintenance guys said he replaced a contactor some time ago, said one wire was burnt..............
09-25-2012, 10:23 PM #9
09-25-2012, 10:33 PM #10
thats what im thinking too^^^ glad the guy finally said something..