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Legend and Notes for Tables 4 and 5
LEGEND:
FL A --- Fu ll L oa d A mp s
MOCP --- Maximu m Overcurrent Protection
{
Motors are designed for satisfactory operation within 10% of
normal voltage shown. Voltages should not exceed the limits
shown in the Voltage Limits column.
NOTES:
1. Minimum circuit amps (MCA) and MOCP values are calcu-
lated in accordance with The NEC. Article 440.
2. Motor FLA values are established in accordance with Under-
writers’ 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 volt-
age imbalance.
4. I nstallation with A ccessory El ectric Heaters
Size the Field Power Wiring between the heater TB1 and the
40RU indoor fan motor per NEC Article 430---28 (1) or (2)
(depends on length of conduit between heater en closure and
40RU power entry location). Install wires in field---installed
conduit.
Example: Supply voltage is 230-3-60
% Volta ge Imbalance = 100 x
max voltage deviation from average voltage
average voltage
AB = 393 v
BC = 403 v
AC = 396 v
Average Voltage =
(393 + 403 +396)
=
1192
3
3
= 397
Determine maximum deviation from a verage 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 imb alance.
% Volta ge Imbalance =100 x
6
397
=1.5%
This amount of p h ase 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.
C10695
Fig. 18 -- Unit Wiring
40RU