SECT
IO
N
2
2-19
T-268-07
2.12 SAFETY AND PROTECTIVE DEVICES
Unit components are protected from damage by safety
and protective devices listed in
Table 2-1
. These
devices monitor the unit operating conditions and open
a set of electrical contacts when an unsafe condition
occurs.
Open safety switch contacts on either or both of devices
IP-CP or HPS will shut down the compressor.
Open safety switch contacts on device IP-CM will shut
down the condenser fan motor.
The entire refrigeration unit will shut down if one of the
following safety devices open: (a) Circuit Breaker(s);
(b) Fuse (F3/15A); or (c) Evaporator Fan Motor Internal
Protector(s) -- (IP-EM).
Table 2-1. Safety and Protective Devices
UNSAFE CONDITION
SAFETY DEVICE
DEVICE SETTING
Circuit Breaker (CB-1) -- Manual Reset
Trips at 29 amps
(460 vac)
Excessive current draw
Circuit Breaker (CB-2,
50
amp) --Manual
Reset
Trips at 62.5 amps
(230 vac)
Circuit Breaker (CB-2,
70
amp) --Manual
Reset
Trips at 87.5 amps
(230 vac)
Excessive current draw on the
control circuit
Fuse (F3)
15 amp rating
Excessive current draw by the
Controller/DataCORDER
Fuse (F1 & F2)
5 amp rating
Excessive condenser fan
motor winding temperature
Internal Protector (IP-CM) -- Automatic
Reset
N/A
Excessive compressor motor
winding temperature
Internal Protector (IP-CP) -- Automatic
Reset
N/A
Excessive evaporator fan
motor(s) winding temperature
Internal Protector(s) (IP-EM) -- Automatic
Reset
N/A
Abnormal
pressures/temperatures in the
high refrigerant side
Fusible Plug -- Used on the Receiver
Rupture Disc -- Used on the Water-Cooled
Condenser
93
_
C = (200
_
F)
35 kg/cm
@
= (500 psig)
Abnormally high discharge
pressure
High Pressure Switch (HPS)
Opens at 25 kg/cm
@
(350 psig)
