Carrier 40RU - Manual (Page 21)

21
Legend and Notes for Tables 4 and 5
LEGEND:
FLA
--- Full Load Amps
MOCP --- Maximum 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. Installation with Accessory Electric 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 enclosure and
40RU power entry location). Install wires in field---installed
conduit.
Example: Supply voltage is 230-3-60
% Voltage 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 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.
% Voltage Imbalance = 100 x
6
397
= 1.5%
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.
C10695
Fig. 18 -- Unit Wiring
40RU