Carrier 69NT40-489-100 Series, Operation And Service Manual

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T-305
13
i. 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
j. Controller Setpoint Range --30 to +30
_
C (--22 to +86
_
F)
2.4 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.
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 1. Safety and Protective Devices
UNSAFE CONDITION SAFETY 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 (F3) 10 amp rating
Excessive current draw by the
controller
Fuse (F1 & F2) 5 amp rating
Excessive current draw by the
emergency defrost circuit
Fuse (FED) 5 amp rating
Excessive current draw by the
drain line heater
Fuse (FDH) 5 amp rating
Excessive current draw by the
humidity power transformer
Fuse (FH) 5 amp rating
Excessive condenser fan mo-
tor 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 mo-
tor(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
Rupture Disc -- Used on the Water-Cooled Con-
denser
99
_
C = (210
_
F)
35 kg/cm
@
= (500 psig)
Abnormally high discharge
pressure
High Pressure Switch (HPS)
Opens at 25 kg/cm
@
(350 psig)