Bryant 580J manual Unbalanced 3-Phase Supply Voltage

TABLE 67 (cont.) MCA/MOCP DETERMINATION NO C.O. OR UNPWRD C.O.

580J

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.	---	Power exhaust
UNPWRD CO	---	Un---powered convenient 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 break- er.

2.Unbalanced 3-Phase Supply Voltage

Never operate a motor where a phase imbalance in supply volt- age is greater than 2%. Use the following formula to determine 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 maxi- mum allowable 2%.

IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact your local electric utility company immediately.

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