Reznor ZQYRA Unit Installation Manual - Manual (Page 14)

Form I-ZQYRA P/N 260414R5, Page 14
7.0 Electrical
Connections
and Wiring
All electrical wiring and connections, including electrical grounding MUST be made
in accordance with the National Electric Code ANSI/NFPA No. 70 (latest edition). In
addition, the installer should be aware of any local ordinances or electric company
requirements that might apply.
See
FIGURE 1, page 4, to show the entrance locations for the high voltage and low
voltage wiring.
7.1 Supply Voltage
Check the rating plate for the supply voltage and current requirements. The electric
supply to the unit must meet stringent requirements for the system to operate properly.
Voltage supply should be within ±10% or as stated on the rating plate. Maximum imbal-
ance 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.
Disconnect Switch
The system may be factory equipped with a built-in non-fusible, lockable disconnect
switch (See location in FIGURE 1, page 4). The built-in disconnect switch (Option BA6)
requires copper wiring with ampacity based on 75°C maximum temperature rating at
the line side terminals.
If the system does not have a built-in disconnect switch, a field-provided or optional
shipped-separate, wall-mounted disconnect switch is required. It is recommended that
there is at least four feet (1.2M) of service room between the wall-mounted switch and
unit access panels. All external wiring must be within approved conduit and have a
minimum temperature rise rating of 60°C. Run conduit so that it does not interfere with
unit access panels. When providing or replacing fuses in a fusible disconnect, use dual
element time delay fuses and size according to the rating plate.
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 - In a 3-phase system, excessive voltage imbalance
between phases will cause compressor motors to overheat and eventually fail. Maxi-
mum allowable imbalance is 2%. To determine voltage imbalance, use recorded volt-
age measurements taken above in the following formula.
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
3-Phase Wiring Connection - There is a chance of unknowingly connecting
3-phase power in such a way as to cause compressor rotation in reverse. To
prevent damage to the components, it is important to check this on startup.
Checking the rotation of the compressor requires connecting pressure gauges
BEFORE startup. Connect refrigerant manifold pressure gauges rated for use with
R410-A refrigerant to the compressor suction and discharge lines.
At startup, observe the gauges.
If the suction pressure rises and discharge pres-
sure 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 compressors are repeatedly allowed to restart and run in reverse, the compres-
sors will be permanently damaged.)
To correct, shut down the unit and turn off the power. At the incoming power con-
nection, switch the 3-phase line voltage wiring connections before restarting the unit.
Recheck the pressure gauges.
CAUTION: Check
compressor
rotation to verify
correct phasing.
DO NOT use fan
rotation to check
phasing. ECM
fans cannot run
backwards.
CAUTION: 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.