55
Legend and Notes for Tables 10 and 11
LEGEND:
BRKR --- Circuit breaker
C.O. --- Convenience outlet
DISC. --- Disconnect
FLA --- Full load amps
LRA --- Locked rotor amps
MCA --- Minimum circuit amps
P. E . --- P o w e r e x h a u s t
Pwrd fr/ unit --- Powered from unit
PWRD C.O. --- Powered convenience outlet
UNPWR C.O. --- Unpowered convenience outlet
NOTES:
1. In comp li an c e with NE C requi rem en ts for mul tim otor and combin ation load
equi pmen t (refer to NEC Artic les 430 and 440), the overcurr ent protective device
for the unit shall be fuse or HACR breaker. Canadian units may be fuse or circuit
breaker .
2. For 208/230 v units, where one value is shown it is the same for either 208 or
230 volts.
3. 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 determine the percentage of voltage
imbalance.
% V oltage Imbalan ce = 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 fro m average voltage.
(AB) 227 – 224 = 3 v
(BC) 231 – 227 = 4 v
(AC) 227 – 226 = 1 v
Maximum deviatio n 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.
50TC
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