E L E C T R I C A L
MODELS WHR-070A THRU 120A
FIELD WIRING 3. Close all circuit breakers in both panels.
4.
Power leads must be run into each panel and be con-
nected to the power terminal block. Table 8, Page 22
gives the recommended lead wire size for each circuit
which is based on the use of 3 conductors in a race-
way. Refer to the National Electric Code for other
type wire or special instructions. All Field wiring
must comply with Local, State and National Electric
Codes.
Close control circuit system switch S1 located on
the outside face of the Left Hand panel.
From the power connection block to the contactors,
overloads and compressor motors, the wiring is fac-
tory installed, ready for operation.
Red power lights LT1 and LT2 will be energized.
Circuit #1 (odd numbered components) will be
energized thru safety controls (Freeze & High
Pressure Controls) and safety light LT3 wi II
light as controls are closed (Normal position).
All compressor motor overload protector relays
MP1 & MP3 will be energized closing contacts
in safety circuit.
5.
6.
Although there is no specific requirement, inter-
locking of a flow switch and the condenser pump
starter (or air cooled condenser fan) is suggested for
the mostdependable and economical system operation.
The cooler pump should operate continuously, even
when the unit is not operating.
Close pump down switch S3 (Auto Position).
S w i t c h #1 on thermostat TC1 closes (due to in-
crease in entering water temperature to cooler) and
followina sequence occurs.
The condenser pump or air cooled condenser fan
should be Field interlocked by connecting toterminals
8, 12, 36, 40 and 14 & 42 in the following manner, and
as indicated in Diagrams 5 and 6.
a.
b.
C .
d.
If the tower or air cooled condenser has only one
pump or fan, jumper terminals 8, 12, 36 and 40 and
connect the motor starter coil to any one of these
terminals, and also to terminal 14 or 42. Power at
these terminals is 220V; therefore, the pump or fan
motor starter coil must be 220 volts.
e.
If two towers or air cooled condensers are used (one
for each circuit), connect one pump or fan starter to
terminals (8 and 12) and 14 and the other pump or fan
to terminals (36 and 40) and 42.
f.
g.
Connecting the unit as indicated above will provide
tower pump or condenser fan operation when any com-
pressor is operating.
Referring to Diagrams 5 and 6, the flow switch is
interlocked by removing jumper between terminals 25
and 26 and wiring the switch contacts into the system
as is shown on the Schematic Wiring Diagrams. When
so wired, the chilled water pump must be operating
before power can be applied to start this system. Note
that the crankcase heaters will be energized regard-
less of water flow. The flow switch is recommended
and does not have the shortcomings of interlocking
the cooler pump starter. A flow switch must be used
for leaving water temperoture of 42 F and lower.
h.
Energizes 10 second time delay relay TD1 to
provide a delay on starting circuit #2.
Energizes light LT5, indicating stage 1 cooling
is required.
Energizes TD3 10 second delay relay to provide
delayed start of compressor 1B.
Energizes run relay R1 closing contacts to open
liquid line solenoid LLS1, allowing liquid re-
frigerant to flow into cooler.
Low side pressure will increase closing Low
pressure switch LP1 energizing compressor con-
tactors Ml and M3 and starting compressor motor
1A (Left Hand).
Non-recycle relay R3 is energized closing con-
tacts R3.
If oil pressure does not build up T2 contact in
oi I pressure, s a f e t y c o n t r o l OP1 will close,
energizing a heater in the control. If pressure
does not build up in 120 seconds, the heater wi II
cause the contacts OP1 to open and shut down
the compressor.
If suction pressure does not build up to 56 psi,
the T2 contact in freeze control will close and
open contacts FS1 after 60 seconds.
7. With a further increase in inlet water temperature,
thermostat switch #2 will close. If 10 seconds has
elapsed since switch #1 closed, contacts TD3 in
time delay relay will be closed.
a. Light LT7 will be energized, indicating that
STARTING SEQUENCE 8.
(Refer to Diagrams 5 & 6)
cooling on stage 2 is required.
b. Relay R5 is energized, closing contacts R5
energizing contactors M5 & M7 starting com-
pressor motor 1B (Left Center).
A further increase in water temperature will close
thermostats 3 and 4, starting compressors 2A and
2B in a similar manner.
Variations or options in the control systems will
change the basic wiring diagrams slightly; however,
the sequence of events will be similar.
The following starting sequence covers one circuit
of a two circuit, four compressor model. The second
circuit operates in a similar manner.
1. Close the main disconnect switches to both cir-
cuits 1 and 2.
9. When compressor contactors Ml, M3, M5 and M7
are eneraized. relays R3 and R7 are eneraized.
a.
b.
2. Power for the control circuit is taken from circuit
#1 power terminal block; therefore, circuit #1 dis-
connect must be closed to run the unit.
The normally closed contacts on R3 will open
whenever compressor is operating, thus turning
off the compressor crankcase heaters.
The normally open contacts R3 and R7 will
close whenever the compressor is operating,
which will run the cooling tower pump or air
cooled condenser fan when connected as in-
structed in Field Wiring section.
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