E L E C T R I C A L
MODELS WHR-008A THRU 060A
F I E L D W I R I N G
Only three main power leads need be hooked up to the
chiller on Models WHR-008A thru 060A. Models WHR-
070A thru 120A have a dual control panel, each sec-
tion handling one circuit of the unit and require separ-
ate service connections to each panel. Table 8, Page
22 gives the recommended lead wire size when only
three conductors are used in a raceway. Refer to the
National Electrical Code for othertype wire or special
instructions.
Although there is no specific requirement,
inter-
locking of a flow switch and the condenser pump start-
er (or air cooled condenser fan) is suggested for the
most dependable and economical system operation.
The cooler pump should operate continuously,
when the unit is not operating.
even
The condenser pump should be field interlocked by
connecting the pump starter coil to terminal 7 and
terminal 12 as shown on Schematic Wiring Diagrams 1
and 2 and terminals 8 & 14 and 12 & 14 on Schematic
Wiring Diagrams 3 and 4, Pages 14 thru 17. This
cycles the condenser pump (or air cooled condenser
fan) with the compressor.
Referring to Diagrams 1 thru 4, the flow switch is
interlocked by removing jumpers between terminals 13
and 14 for single units and 25 and 26 for dual units,
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 be-
fore 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
the cooler pump starter. A flow switch must be used
for leaving water temperature of 42 F and lower.
STARTING SEQUENCE
(Refer to Diagrams 1 thru 4)
Variations or options
in the control system will
change the basic wiring diagrams slightly, however,
the sequence of events will be similar.
The following starting sequence is for dual com-
pressor units. The sequence for single compressor
units is identical except for the obvious reference to
the second unit. Once the system ON-OFF switch is
pushed on the ON position, the unit will operate com-
pletely automatically.
1. Check or throw to “auto” position switches S3
and S4 (pumpdown switches). Switch is in “auto”
position during normal operation.
2. With main power on, power to the control circuit
from L1 and L2 is fed through fuse F1 to terminal
COMPRESSOR LOCATION
WHR-020A THRU 060A
FIGURE NO. 17
TOP VIEW OF UNIT
M o d e l s WHR-OO8A thru 015A are
single compressor units.
3.
4.
5.
6.
7.
8.
9.
10.
25. The power from 25 is fed thru NC contacts to
relay R3 and R4 to energizethe compressor crank-
case heaters, when the compressors are not oper-
ating. The indicator lights should show the heaters
on. Power is also supplied to the main system On-
Off switch, S1.
Closing switch S1 energizes System No. 1 and
System No. 2.
Referring to System No. 1, power at terminal 2 in-
dicates power to the system by lighting the red
“Power on” liaht.
P r o v i d e d operating
safety controls are closed
(FS1, OP1, HP1 and MP1 or OL1 w h e n e x t e r n a l
overloads are used), power at terminal 3 will ener-
gize safety light, indicating the system is ready
to run.
Referring to the standard non-recycle, pumpdown
operation of the Schematic Wiring Diagram, relay
R1 and R3 are normally open and power cannot
reach compressor starter. Power can reach starter
only by energizing R1 which is controlled by ther-
mostat TC1 through the compressor lead-lag switch
(dual units only) and the pumpdown switch S3.
When cooling is required, power is supplied to
terminal 4 through water thermostat TC1 energiz-
ing relay R1, indicator light LT5.
When R1 relay is energized, contact R1 will close
and open the liquid line solenoid valve LLS1.
If low pressure control LP1 is open, the opening
of LLS1 will allow refrigerant to flow into the low
side building up pressure which will close LP1
and the compressor will start.
Meanwhile, time delay TD3 is timing the second
compressor. After the time delay closes, power is
fed to control system No. 2 and the same sequence
of starting for the second compressor is repeated.
O F F C Y C L E
Referring to the Schematic Wiring Diagrams
when
t h e r m o s t a t TC1 is satisfied, the electrical circuit to
terminal No. 4 (or No. 10 for second system), will be
broken opening relay R1 de-energizing the liquid line
solenoid and indicator light LT5. The compressor wi II
continue to operate through the contacts of R3 relay.
Note that R3 relay is now energized through its own
contacts and the compressor is on the pumpdown
cycle. When the compressor has pumped most of the
liquid refrigerant from the cooler, the low pressure
cut out, LP1 will open and de-energize R3 relay. This
locks the compressor off the line until the thermostat
TC1 calls for cooling again, energizing LLS1 and R1
and closing LPI.
COMPRESSOR HORSEPOWER
TABLE NO. 6
M O D E L
N U M B E R
C O M P R E S S OR NOMINAL HP
1 C O M P . 2
WHR-008A 7%
10
15
. . ...1-020A
10
15 15
2 0
2 0
WHR-050A 2.5
W H R - 0 6 0 A
35
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