Carrier 69NT40-541-505, Operation And Service Manual, Page: 28 / 143

T-368 3–8
3.4 SAFETY AND PROTECTIVE DEVICES
Unit components are protected from damage by safety and protective devices listed in the following table. These
devices monitor the unit operating conditions and open a set of electrical contacts when an unsafe condition occurs.
ELECTRICAL DATA (Continued)
h. 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% 0.99V
50% 1.65V
70% 2.31V
90% 2.97V
i. Controller Setpoint Range -30 to +30°C ( -22 to +86°F)
Table 3–1 Safety and Protective Devices
UNSAFE CONDITION SAFETY DEVICE DEVICE SETTING
Excessive current draw
Circuit Breaker (CB-1) − Manual Reset Trips at 29 amps (460VAC)
Circuit Breaker (CB-2, 50 amp) − Manual Reset Trips at 62.5 amps (230VAC)
Circuit Breaker (CB-2, 70 amp) − Manual Reset Trips at 87.5 amps (230VAC)
Excessive current draw in
control circuit Fuse (F3A & F3B) 7.5 amp rating
Excessive current draw by
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 /
temperatures in the high
refrigerant side Fusible Plug − Receiver 99°C = (210°F)
Abnormally high discharge
pressure High Pressure Switch (HPS) − Automatic Reset Open at 25kg/cm@ (350psig)
Close at 18kg/cm@ (250psig)
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