Carrier 50HJ015 - Page 16

Protective Devices
COMPRESSOR PROTECTION
Overcurrent — Each compressor has one manual reset, cal¬
ibrated trip, magnetic circuit breaker. Do not bypass con¬
nections or increase the size of the circuit breaker to correct
trouble. Determine the cause and correct it before resetting
the breaker.
Overtemperature — Each compressor has an internal pro¬
tector to protect it against excessively high discharge gas
temperatures.
Crankcase Heaters — Each compressor has 125-watt crank¬
case heaters to prevent absorption of liquid refrigerant by
oil in the crankcase when the compressor is idle. Since power
for the crankcase heaters is drawn from the unit incoming
power, main unit power must be on for the heaters to be
energized.
IMPORTANT: After a prolonged shutdown or serv¬
ice job, energize the crankcase heaters for 24 hours
before starting the compressors
Compressor Lockout — If any of the safeties (high- or low-
pressure, freeze protection thermostat, compressor internal
thermostat) trip, or if there is loss of power to the compres¬
sors, the CLO (compressor lockout) will lock the compres¬
sors off. To reset, manually move the thermostat
setting.
EVAPORATOR-FAN MOTOR PROTECTION - A man¬
ual reset, calibrated trip, magnetic circuit breaker protects
against overcurrent. Do not bypass connections or increase
the size of the breaker to correct trouble. Determine the
cause and correct it before resetting the breaker.
CONDENSER-FAN MOTOR PROTECTION - Each
condenser-fan motor is internally protected against over¬
temperature.
HIGH- AND LOW-PRESSURE SWITCHES - If either
switch trips, or if the compressor overtemperature switch
activates, that refrigerant circuit will be automatically locked
out by the CLO To reset, manually move the thermostat
setting
FREEZE PROTECTION THERMOSTAT (FPT) - An
FPT is located on the evaporator coil. It detects frost
buildup and turns off the compressor, allowing the coil to
clear. Once the frost has melted, the compressor can be
reenergized by resetting the CLO from the thermostat.
Relief Devices — All units have relief devices to pro¬
tect against damage from excessive pressures (i.e., fire).
These devices protect the high and low side.
Control Circuit, 24-V — This control circuit is pro¬
tected against overcurrent by a 3.2-amp circuit breaker. Breaker
can be reset. If it trips, determine cause of trouble before
resetting.
Replacement Parts — A complete list of replace¬
ment parts may be obtained from any Carrier distributor
upon request.
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