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49
Legend and Notes for Table 11
LEGEND:
BRKR --- Circuit breaker
CO --- Convenience outlet
DISC --- Disconnect
FLA --- Full load amps
LRA --- Locked rotor amps
MCA --- Minimum circuit amps
PE --- Power exhaust
PWRD CO --- Powered convenient outlet
UNPWR CO --- Unpowered c onvenient outlet
NOTES:
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. 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 =100x
max voltage deviation from average voltage
averagevoltage
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 p ercent 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.
48HC