Damn Electrics

[Brian_UK]

Had an interesting little electrical problem on an A/C unit today.

An old unit which had tripped it's 3 phase breaker. Performed the usual checks, earth leakage, shorted components etc. without finding any real problem. Admittedly this was only using a multimeter, albeit a good one.

Suspected a transformer, then a pump, then a relay; I seemed to be chasing a fault that came and went.

Rebuilt the circuits and applied power again - all seemed to be OK

Then, pop - lost a single phase. Started again but watched this particular phase, power stayed in but a slight burning smell started which didn't best please me I must say.

Finally found the cause by following the small plume of smoke coming from the terminal strip of the condensing unit. The terminal block insulation was breaking down and the thing was tracking down to earth.

Change the wiring and away we go again, I love these pain in the butt jobs don't you?

[Gary]

I've found an infrared thermometer is useful for tracking the telltale hot spots. Still a pain, but perhaps a little less so.

If refrigeration were easy, everyone would be doing it.

[Brian_UK]

Originally posted by Gary
I've found an infrared thermometer is useful for tracking the telltale hot spots

Yes, so do I now, but this onbe was cold when I got there and wouldn't stay in longer enough to test, but your point is well taken Gary.

[C J]

I have seen the same frustration in the face , a puzzeled look from the tech assistants on my staff. The 3 phase starters for the evaporators especially. I have seen the results of their oversite, and tell them try not to practice BASIC ARC WELDING 101......


C J