A compressor condition and failure not often discussed is
Terminal Venting. Terminal Venting is a result of an electrical ground fault occurring
in the compressor with one or more of the compressor terminals being ejected
from the compressor shell. Obviously when
this occurs, any refrigerant and oil in the compressor is vented / discharged through
the terminal opening to the atmosphere. The refrigerant and oil mixture will be
discharged at the pressure of low side pressure at the time of the failure. In addition to the
oil being hot, the oil and refrigerant mixture can ignite as a result of the
ground fault resulting in a potential fire hazard.
Safety is paramount; you should never under any circumstance
apply power to a compressor with the compressor terminal cover removed. In addition
to the safety hazards listed above, the terminal can be discharged with the
force of a 22 caliber bullet.
A terminal venting condition has a higher probability of
occurring if a ground fault condition exists and power is reapplied to the
compressor by either resetting a breaker or replacing a fuse. If an over
current device is found open, the unit should be checked for a ground fault
using a megohmmeter (megger). A standard
ohmmeter may not detect a ground fault under certain conditions. In addition to
following standard safety practices related to electric, use extreme caution
when removing the compressor terminal cover and disconnecting compressor
wiring. The compressor terminal pins could have become weakened from the
initial ground fault or the equipment owner could have reset the breaker (more
than likely several times) which could further lead to a deteriorating pin assembly.
Be safe and always wear proper PPE.
