Table 2 — Electrical Data
OUTDOOR
UNIT 38QR
V-PH-HZ
OPERATIONAL
VOLTAGE*
COMPR
FAN
FLA
MCA
MAX FUSE†
OR HACR TYPE
CKT BKR AMPS
Max
Min
LRA
RLA
018C
208/230-1-60
253
187
49.0
8.9
.70
11.8
20
024C
61.0
10.9
.70
14.3
25
030C
76.0
13.5
.70
17.6
30
036C
90.5
17.9
.70
23.1
40
048C
110.0
22.4
1.45
29.5
50
060C
135.0
27.6
1.50
36.0
60
036C
208/230-3-60
253
187
66.0
11.2
1.45
15.5
20
048C
92.0
14.7
1.45
19.8
40
060C
105.0
17.7
1.50
23.6
45
036C
460-3-60
506
414
35.0
5.8
.80
8.1
15
048C
46.0
6.7
.80
9.2
15
060C
55.0
10.4
.83
13.8
20
LEGEND
FLA
— Full Load Amps
HACR — Heating, Air Conditioning, Refrigeration
LRA
— Locked Rotor Amps
MCA
— Minimum Circuit Amps per NEC Section 430-24
NEC
— National Electrical Code
RLA
— Rated Load Amps (Compressor)
*Permissible limits of the voltage range at which unit will operate sat-
isfactorily.
†Time-delay fuse.
NOTES:
1. Control circuit is 24 v on all units and requires an external power
source.
2. All motors and compressors contain internal overload protection.
3. In compliance with NEC requirements for multimotor and combi-
nation load equipment (refer to NEC Articles 430 and 440), the
overcurrent protective device for the unit shall be fuse or HACR
breaker.
4. Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance in supply volt-
age is greater than 2%.
Use the following formula to determine
the % voltage imbalance.
% Voltage Imbalance
= 100 x
max voltage deviation from average voltage
average voltage
Filter Drier —
Whenever the moisture liquid indicator
shows presence of moisture, replace the filter drier. Refer to
Carrier Standard Service Techniques Manual, Chapter 1, Re-
frigerants, for details on servicing filter driers.
High-Pressure Switch —
This switch, located on dis-
charge line, protects against high discharge pressures caused
by such events as overcharge, outdoor-fan motor failure, sys-
tem restriction, etc. It opens on pressure rise at about
426 psi. If system pressures go above this setting during ab-
normal conditions, the switch opens.
DO NOT attempt to simulate the system abnormalities
— high pressures pose a serious safety hazard.
High-pressure switch is also checked with an ohmmeter
similar to checking low-pressure switch. If system pressure
is below 426 psi, switch shows continuity.
Low-Pressure Switch —
This switch, mounted on
the suction line, has fixed, non-adjustable settings. The switch
is bypassed during defrost, and also for the first 2 minutes of
heating operation after defrost, by means of a time-delay
Example: Supply voltage is 460-3-60.
AB = 452 v
BC = 464 v
AC = 455 v
452 + 464 + 455
Average Voltage =
3
1371
=
= 457
3
Determine maximum deviation from average voltage.
(AB) 457 – 452 = 5 v
(BC) 464 – 457 = 7 v
(AC) 457 – 455 = 2 v
Maximum deviation is 7 v.
Determine % voltage imbalance.
% Voltage Imbalance = 100 x
7
= 1.53%
457
This amount of phase imbalance is satisfactory as it is below the maxi-
mum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance
is more than 2%, contact your local electric utility com-
pany immediately.
relay. This prevents nuisance tripping of the low-pressure
switch.
To check pressure switch, attach pressure gage to suction
service valve gage port. Slowly close liquid shutoff valve
and allow compressor to pump down. Do not allow com-
pressor to pump down below 2 psig. Compressor should shut
down when suction pressure drops to cutout pressure in
Table 1, and should restart when pressure builds up to cut-in
pressure shown after CLO (compressor lockout switch) has
been reset and accessory Time Guard® device has com-
pleted its timing cycle.
Crankcase Heater —
Heater prevents refrigerant mi-
gration and compressor oil dilution during shutdown when
compressor is not operating. If crankcase heater is deener-
gized for more than 6 hours, both compressor service valves
must be closed.
Crankcase heaters come in 2 basic types: wraparound (bel-
lyband) type that is wrapped externally around compressor
shell, and insertion type that is inserted into compressor oil
well in shell of compressor.
Crankcase heater is powered by high-voltage power of unit.
It is connected across the line side of the contactor and op-
erates continually. Use extreme caution when troubleshoot-
ing this device with power on.
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