LEGEND AND NOTES FOR TABLES 2A AND 2B
| LEGEND |
FLA | — Full Load Amps |
HACR | — Heating, Air Conditioning and Refrigeration |
IFM | — |
% Voltage Imbalance
max voltage deviation from average voltage
= 100 x
average voltage
LRA | — Locked Rotor Amps |
MCA | — Minimum Circuit Amps |
MOCP | — Maximum Overcurrent Protection |
NEC | — National Electrical Code |
OFM | — |
RLA | — Rated Load Amps |
Example: Supply voltage is
AB = 452 v
BC = 464 v
AC = 455 v
Average Voltage =
452 + 464 + 455
3
*Heaters are field installed only.
†Used to determine minimum disconnect per NEC.
**Heater capacity (kW) is based on heater voltage of 208 v, 240 v, or 480 v and 575 v. If power distribution voltage to unit varies from rated heater voltage, heater kW will vary accordingly.
1371
=
3
= 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.
††Fuse or HACR circuit breaker.
Optional disconnect switch is unavailable. (Applies to units with an FLA greater or equal to 80.)
NOTES:
% Voltage Imbalance = 100 x
= 1.53%
7
457
1.In compliance with NEC requirements for multimotor and combination load equipment (refer to NEC Articles 430 and 440), the overcurrent protective device for the unit shall be fuse or HACR breaker.
2.Unbalanced
Never operate a motor where a phase imbalance in supply voltage is greater than 2%. Use the following formula to determine the percentage of voltage imbalance.
This amount of phase imbalance is satisfactory as it is below the maximum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is more than 2%, con- tact your local electric utility company immediately.
