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Legend and Notes for Table 5
LEGEND:
BRKR --- Circuit breaker
CO --- Convenient outlet
DISC --- Disconnect
FLA --- F ull load amps
LRA --- Locked rotor amps
MCA --- Min imum circuit amps
PE --- Powe r exh aust
PWRD CO --- Powered convenient outlet
UNPWR CO --- Unpowered convenient outlet
NOTES:
1. In compliance with NEC requirements for multimotor and
combination l oad equipment (refer to NEC Articles 430 and
440), the overcurrent protective device for the unit shall be
fuse or HACR breaker. Canadian units may be fuse or circuit
breaker.
2. Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance in supply
voltage is greater than 2%. Use the following formula to de-
termine the percentage of voltage imbalance.
% Voltage Imbalance =100 x
max voltage deviation from average voltage
average voltage
Example: Supply voltage is 230-3-60
AB = 224 v
BC = 231 v
AC = 226 v
Average Voltage =
(224 + 231 +226)
=
681
3
3
= 227
Determine maximum deviation from average voltage.
(AB) 227 – 224 = 3 v
(BC) 231 – 227 = 4 v
(AC) 227 – 226 = 1 v
Maximum deviation is 4 v.
Determine percent of voltage imbalance.
% Voltage Imbalance =100 x
4
227
= 1.76%
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%, contact your local electric utility company immediately.
581J