centrifugal motor by trane

[goshen]

hi i have a trane unit ecvge 300 ton unit that runs ok for approx 45 minutes ,loading and unloding ,vane motor is ok ,but motor peeks all of a sudden to 450 amps! with a lot of noise ,and shuts down .nominal current of motor is 364. but unit is current limited to 85%,one phase draws 12 amps more than the other two but this condition has been going for about 9 years!unit does not shake or vibrate ,contactors seem ok ,main circuit braker does not trip
anyone ever encounter such a problem??i know some old units made by trane had motor problems but they caused problems much earlier not 10 years later!!
urgent thanks:eek:

[Toosh]

hi i have a trane unit ecvge 300 ton unit that runs ok for approx 45 minutes ,loading and unloding ,vane motor is ok ,but motor peeks all of a sudden to 450 amps! with a lot of noise ,and shuts down .nominal current of motor is 364. but unit is current limited to 85%,one phase draws 12 amps more than the other two but this condition has been going for about 9 years!unit does not shake or vibrate ,contactors seem ok ,main circuit braker does not trip
anyone ever encounter such a problem??i know some old units made by trane had motor problems but they caused problems much earlier not 10 years later!!
urgent thanks:eek:

Hi Goshen, First of all what is the refrigerant in the system and what are the running pressures, have you measured the voltage, Im taking a guess that there is air in the system.

Norm

[goshen]

hi garry refrigerant is R-134a and all pressures are normal 250 on low side and approx 700 on high side unit is water condensed and like i said runs ok for 45 minutes

[hendry]

this 3 phase motor must be checked on its phase-ro-phase balance.
off phase operation happens.
but, how much it is out of norm that counts!
why don't you send the motor for checks by motor specialist?

if you are compentent like us ... do a mega on the motor's coil or running smaller amps thru empty coil to checks the coils conditions.

hope that helps.

[ptsac]

The sudden rise in motor Amps could be caused by liqiud return, however I would have expected that to be not so noisy. Is there a possibility that chilled water flow is affected after a period of operation? What, if any, fault is the chiller locking out on?

[goshen]

hi turns out the condenser is dirty approach at 100% capacity is 7 c
and current transformer is off by 35 amps motor is ok althogh this motor is indeed small for this unit and that is why the over current protection kicked in before surge protection at full capacity