10
LEGEND AND NOTES FOR TABLE 2
LEGEND
*Heater capacity (kW) is based on heater voltage of 208 v, 240 v,
480 v, and 600 v. Heaters are rated at 240 v, 480 v, or 600 v. If
power distribution voltage to unit varies from rated heater voltage,
heater kW will vary accordingly. To determine heater capacity at
actual unit voltage, multiply 240 v, 480 v, or 600 v capacity by mul-
tipliers found in table below.
†Used to determine minimum disconnect size per NEC.
**Heaters are field installed only.
††Fuse or HACR circuit breaker.
||Fusing in single point box provides the required branch circuit
protection.
NOTES:
1. In compliance with NEC requirements for multimotor and com-
bination load equipment (refer to NEC Articles 430 and 440),
the overcurrent protective device for the unit shall be fuse or
HACR breaker. The Canadian units may be fuse or circuit
breaker.
2.
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 percent of voltage imbalance.
% Voltage Imbalance
Example: Supply voltage is 460-3-60.
AB = 452 v
BC = 464 v
AC = 455 v
= 457
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 percent of voltage imbalance.
% Voltage Imbalance = 100 x
= 1.53%
This amount of phase imbalance is satisfactory as it is below
the maximum allowable 2%.
3. Determine heater capacity using multiplication factors table
below:
NOTE: The following equation converts kW of heat energy to Btuh: kW x 3.412 =
Btuh.
EXAMPLE: 32.0 kW (at 240 v) heater on 208 v
= 32.0 (.751 mult factor)
= 24.0 kW capacity at 208 v
FLA —
Full Load Amps
HACR—
Heating, Air Conditioning and Refrigeration
IFM —
Indoor (Evaporator) Fan Motor
LRA —
Locked Rotor Amps
MCA —
Minimum Circuit Amps
MOCP—
Maximum Overcurrent Protection
NEC —
National Electrical Code
OFM —
Outdoor (Condenser) Fan Motor
RLA —
Rated Load Amps
= 100 x
max voltage deviation from average voltage
average voltage
Average Voltage =
452 + 464 + 455
3
=
1371
3
IMPORTANT: If the supply voltage phase imbalance is
more than 2%, contact your local electric utility company
immediately.
HEATER
RATING
VOLTAGE
ACTUAL HEATER VOLTAGE
200 208 230 240 380 440 460 480 550 575 600
240
0.694 0.751 0.918 1.000 — — — — — — —
480
— — — — 0.626 0.840 0.918 1.000 — — —
600
————————0.8400.9181.000
7
457
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