Reznor SHH (Indoor PreevA) Unit Installation Manual - Manual (Page 44)

Form I-PDH/SDH/PEH/SHH/PXH, Page 44
The electric supply to the unit must meet stringent requirements for the system to oper-
ate properly. Voltage supply should be within ±10% or as stated on the rating plate.
Maximum imbalance on a 3-phase system is 2%. Follow instructions below to check.
CAUTION: If this unit is allowed to operate on an electric supply that is
not within the specified tolerances, the product warranty shall be void.
See Hazard Levels, page 2.
If the power supply is not within these tolerances, contact the power company prior to
operating the system.
Check Voltage Supply - See voltage use range on the rating plate. Measure (and
record) each supply leg voltage at all line disconnect switches. Readings must fall
within the allowable range.
Check Voltage Imbalance (applies to units with optional reheat compressor) - In
a 3-phase system, excessive voltage imbalance between phases will cause compres-
sor motor to overheat and eventually fail. Maximum allowable imbalance is 2%. To
determine voltage imbalance, use recorded voltage measurements taken above in the
following formula.
NOTE: These
requirements and
procedures would also
apply to compressors on
the condensing unit.
Disconnect Switch - A disconnect switch is available as optional equipment or may
be supplied locally. When installing the disconnect switch, be careful that the conduit
and switch housing are clear of all service doors. Allow at least four feet (1.2M) of ser-
vice room between the disconnect switch and any service panels. When providing or
replacing fuses in a fusible disconnect switch, use dual element time delay fuses and
size 1.25 times the maximum total input amps.
7.2.2 Supply Wiring
Options
DANGER
To prevent injury or death due to electrocution or contact
with moving parts, lock disconnect switch open. See Hazard
Levels, page 2.
Key: V1, V2, V3 = line voltages as measured
VA (average) =
(V1 + V2 + V3)
3
VD = line voltage (V1, V2, or V3) that deviates farthest from average (VA)
Formula:
% Line Voltage Imbalance =
[100 x (VA -VD)]
VA
Reheat Compressor Wiring (applies to units with optional reheat compressor) - A
3-phase scroll compressor must be phased correctly or compressor will operate in
reverse. Since there is a chance of unknowingly connecting the power in such a
way as to cause compressor rotation in reverse, it is important to check this on
startup.
CAUTION Be sure to connect pressure gauges to the suction and
discharge lines before startup so that compressor rotation can
be checked immediately. Scroll compressors will be destroyed if
operated in the wrong direction. See Hazard Levels, page 2.
Before initial startup, connect refrigerant pressure gauges to the compressor suction
and discharge lines. At startup, observe the gauges. If the suction pressure rises and
discharge pressure drops, the compressor is operating in reverse and should be
shut down. (After several minutes of operation in reverse, the compressor’s internal
protector will trip. If a compressor is repeatedly allowed to restart and run in reverse,
the compressor will be permanently damaged.) Turn off the power and switch the
3-phase line voltage wiring connections before restarting the unit.
Blower Motor Wiring - Check rotation of the blower. If rotation is not correct, three-
phase motor may be reversed by interchanging two wires on the 3-phase supply con-
nection.
7.0 Electrical
Supply and
Wiring (cont’d)
7.2 Supply Wiring
(cont’d)