19
After wiring is in control box, make connection to proper
terminals on terminal blocks (see Field Control Wiring section
on page 28).
Affix crankcase heater sticker (located in the installers
packet) to unit disconnect switch.
Voltage to compressor terminals during compressor opera-
tion must be within the voltage range indicated on the unit
nameplate. On 3-phase units, phases must be balanced within
2%.
Use the formula in Table 4 to determine the percentage of
voltage imbalance.
Unit failure as a result of operation on improper line voltage
or excessive phase imbalance constitutes abuse and may cause
damage to electrical components.
LEGEND AND NOTES FOR TABLE 4
LEGEND
*Fuse or HACR circuit breaker per NEC.
NOTES:
1. In compliance with NEC requirements for multi motor and combi-
nation load equipment (refer to NEC Articles 430 and 440), the
overcurrent protective device for the unit shall be fuse or HACR
breaker. The Canadian units may be fuse or circuit breaker.
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 percent of voltage imbalance.
% Voltage imbalance
Example: Supply voltage is 460-3-60.
AB = 452 v
BC = 464 v
AC = 455 v
= 457
Determine maximum deviation from average voltage.
(AB) 457 – 452 = 5 v
(BC) 464 – 457 = 7 v
(AC) 457 – 455 = 2 v
Maximum deviation is 7 v.
Determine percent of voltage imbalance.
% Voltage Imbalance = 100 x
= 1.53%
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
IMPORTANT: The VAV (variable air volume) units use
variable frequency drives, which generate, use and can
radiate radio frequency energy. If units are not installed and
used in accordance with these instructions, they may cause
radio interference. They have been tested and found to
comply with limits of a Class A computing device as
defined by FCC (Federal Communications Commission)
regulations, Subpart J of Part 15, which are designed to
provide reasonable protection against such interference
when operated in a commercial environment.
The unit must be electrically grounded in accordance with
local codes and NEC ANSI/NFPA 70 (National Fire Pro-
tection Association).
IMPORTANT: If the supply voltage phase imbalance is
more than 2%, contact your local electric utility company
immediately.
FLA —
Full Load Amps
HACR —
Heating, Air Conditioning and
Refrigeration
LRA —
Locked Rotor Amps
MCA —
Minimum Circuit Amps
MOCP —
Maximum Overcurrent Protection
NEC —
National Electrical Code
RLA —
Rated Load Amps
= 100 x
max voltage deviation from average voltage
average voltage
Average Voltage =
452 + 464 + 455
3
=
1371
3
IMPORTANT: If the supply voltage phase imbalance is
more than 2%, contact your local electric utility company
immediately.
7
457
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