20
Legend and Notes for Tables 10-13
LEGEND
* Motors are designed for satisfactory operation within 10% of normal
voltage shown. Voltages should not exceed the limits shown in the Volt-
age Limits column.
NOTES:
1. Minimum circuit amps (MCA) and maximum overcurrent protection
(MOCP) values are calculated in accordance with The NEC. Article
440.
2. Motor FLA values are established in accordance with Underwriters’
Laboratories (UL). Standard 1995.
3. Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance in supply voltage
is greater than 2%. Use the formula in the example (see column to
the right) to determine the percentage of voltage imbalance.
4. Installation with Accessory Electric Heaters
Size the Field Power Wiring between the heater TB1 and the 524J
indoor fan motor per NEC Article 430-28 (1) or (2) (depends on
length of conduit between heater enclosure and 524J power entry
location). Install wires in field-installed conduit.
Example: Supply voltage is 230-3-60
Determine maximum deviation from average voltage.
(AB) 397-393 = 4 v
(BC) 403-397 = 6 v
(AC) 397-396 = 1 v
Maximum deviation is 4 v.
Determine percent of voltage imbalance.
This amount of phase imbalance is satisfactory as it is below the maxi-
mum allowable 2%.
FLA
— Full Load Amps
HACR
— Heating, Air Conditioning, and Refrigeration
%Voltage
Imbalance:
= 100 x
max voltage deviation from average voltage
average voltage
AB = 394 v
BC = 403 v
AC = 396 v
Average Voltage =
(393 + 403 + 396)
=
1192
3
3
=
397
% Voltage Imbalance = 100x
6
397
= 1.5
IMPORTANT: If the supply voltage phase imbalance is more than 2%,
contact your local electric utility company immediately.
A
B
C
MOTOR
