Gas Heater User Manual

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TABLE 67 (cont.) MCA/MOCP DETERMINATION NO C.O. OR UNPWRD C.O.
LEGEND:
C.O. --- Convenience outlet
DISC --- Disconnect
FLA --- Full load amps
IFM --- Indoor fan motor
LRA --- Locked rotor amps
MCA --- Minimum circuit amps
MOCP --- Maximum over current protection
P. E . --- P o w e r e x h a u s t
U N P W R D C O --- U n --- p o w e r e d c o n v e n i e n t o u t l e t
NOTES:
1. In compliance with NEC requirements for multimotor and
combination load equipment (refer to NEC Articles 430 and
440), th e overcurrent protective device for the uni t shall be fuse
or HACR breaker. Canadian units may be fuse or circuit break-
er.
2. Unbalanced 3-Ph ase Supply Voltage
Never operate a motor where a phase imbalance in supply volt-
age is greater than 2%. Use the following formula to determine
thepercentageofvoltageimbalance.
% Voltage Imbalance = 100 x
max voltage deviation from average voltage
average voltage
Example: Su pply voltage is 230-3- 60
AB = 224 v
BC = 231 v
AC = 226 v
Average Voltage =
(224 + 231 + 226)
=
681
3
3
= 227
Determine m aximum 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 im balance.
% Voltage Imbalance = 100 x
4
227
= 1.76%
This amount of phase imbalance is satisfactory as it is below the maxi-
mum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is more than 2%,
contact your local electric u tility company imm ediately.
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