Carrier WeatherExpert 48N2 Installation Instructions Manual page 30
Packaged rooftop cooling units with gas heat and comfortlink controls
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Unit failure as a result of operation on improper line voltage or ex-
cessive phase imbalance constitutes abuse and may cause damage
to electrical components.
Determine percent voltage imbalance:
% Voltage Imbalance = 100 x
Check proper rotation of the compressors. If they rotate in reverse
change the phasing of the main power not the compressors.
NOTE: Do not depend on fan rotation for proper phasing; the
VFDs will correct for swapped phases.
Check current draw of VFD and motor for proper phase balance.
All currents at 60 Hz should be within 5% of each other and the
rated load amps or a line reactor may be required to correct for
building or grid phase shifts. Check the building supply for proper
phasing of 120 degrees.
TB1
21
11
12
22
13
23
EQUIP GND
LEGEND
EQUIP — Equipment
GND
— Ground
NEC
— National Electrical Code
TB
— Terminal Block
Fig. 21 — Field Power Wiring Connections
NOMINAL
BkW
HP
7.5
5.6
10
7.5
15
11.2
20
14.9
25
18.7
30
22.4
40
29.8
50
37.3
60
44.8
75
59.5
100
74.6
LEGEND
Bhp — Brake Horsepower
BkW — Brake Kilowatts
7
457
= 1.53%
DISCONNECT PER NEC
Table 7 — Motor Limit
MAX BHP
MAX BkW
8.6
6.39
11.5
8.56
17.3
12.89
22.9
17.10
28.7
21.41
34.5
25.71
45.9
34.27
57.4
42.83
68.9
51.41
86.1
64.25
114.8
85.67
FACTORY-INSTALLED
POWER
DISCONNECT
WIRING
HANDLE LOCATION
ENTRY
Fig. 22 — Factory-Installed Disconnect Location (End
of Unit Shown)
FACTORY
WIRE
23
22
21
DISCONNECT
PER NEC
13
12
11
FIELD
WIRE
Fig. 23 — Field Power Wiring Connections
for Factory-Installed Disconnect
MAX AMPS (EA)
460 V
12.0
14.3
22.0
28.7
36.3
41.7
55.0
71.0
83.0
101.0
132.0
NOTE: Extensive motor and electrical testing on the Carrier units has
ensured that the full horsepower range of the motor can be utilized with
confidence. Using fan motors up to the horsepower ratings shown in the
Motor Limitations table will not result in nuisance tripping or premature
motor failure. Unit warranty will not be affected.
30
EQUIP
GND
LEGEND
EQUIP — Equipment
GND
— Ground
NEC
— National Electrical Code
RATED
EFFICIENCY
575 V
10.0
91.7
12.0
91.7
19.0
93.0
23.0
93.6
28.4
93.6
36.3
94.1
43.8
94.1
52.8
94.5
60.5
95.0
80.5
95.0
106.0
95.4
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