Carrier 69NT40-561-019, Operation And Service Manual

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T-359 3–8
3.4 SAFETY AND PROTECTIVE DEVICES
Unit components are protected from damage by safety and protective devices listed in Table 3–1 . These de vices
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
(F3A/F3B, 7.5A); or (c) evaporator fan motor internal protector(s) - (IP).
m. Humidity Sensor Orange wire Power
Red wire Output
Brown wire Ground
Input voltage 5 VDC
Output voltage 0 to 3.3 VDC
Output voltage readings verses relative humidity (RH) percentage:
30% 0.99 V
50% 1.65 V
70% 2.31 V
90% 2.97 V
Table 3–1 Safety and Protective Devices
UNSAFE CONDITION DEVICE DEVICE SETTING
Excessive current draw
Circuit Breaker (CB-1) - Manual Reset Trips at 29 amps (460 VAC)
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
in the control circuit
Fuse (F3A & F3B) 7.5 amp rating
Excessive current draw
by the controller
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/tempera-
tures in the high refrigerant side
Fusible Plug - Used on the Receiver 99

C = (210

F)
Abnormally high
discharge pressure
High Pressure Switch (HPS)
Opens at 25 kg/cm
2

(350 psig)