Carrier 69NT40-561-300, Operation And Service Manual

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T-365 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 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
(F3A/F3B, 7.5A); or (c) evaporator fan motor internal protector(s) - (IP).
DUV Coil 24VAC Nominal Resistance @
68°F (20°C)
15.5 ohms +/- 5%
EEV Nominal Resistance
Coil Feed to Ground (Gray
Wire)
47 ohms
Coil Feed to Coil Feed 95 ohms
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 3–2 Safety and Protective Devices
UNSAFE CONDITION DEVICE DEVICE SETTING
Excessive current draw
Circuit Breaker (CB-1, 25 amp) -
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 con-
troller Fuse
Fuse (F1 & F2) 5 amp rating
Excessive current draw by the Emer-
gency Bypass module
Fuse (FEB) 10 amp rating
Excessive condenser fan motor
winding temperature Internal Protector (IP-CM) - Automat-
ic Reset
N/A
Excessive compressor motor wind-
ing temperature Internal Protector (IP-CP) - Automat-
ic Reset
N/A
Excessive evaporator fan motor(s)
winding temperature Internal Protector(s) (IP-EM) - Auto-
matic Reset
N/A