47
RLC-SVX02G-E4
Installation – Electrical
Refer to Freeze Protection section
for information about the
evaporator circulating pump.
The relay output from (A5-2) or
(A5-3) is required to operate the
evaporator water-pump (CHWP)
contactor. Contacts should be
compatible with a 115/230 V (ac)
control circuit. The CHWP relay
operates in different modes
depending on CH.530 or Tracer
commands, if available, or service
pumpdown (see maintenance
section). Normally, the CHWP relay
follows the AUTO mode of the
chiller. Whenever the chiller has no
diagnostics and is in the AUTO
mode, regardless of where the auto
command is coming from, the
normally-open relay is energized.
When the chiller exits the AUTO
mode, the relay is timed open for an
adjustable (using TechView) 0 to 30
minutes. The non-AUTO modes in
which the pump is stopped include
Reset (88), Stop (00), External Stop
(100), Remote Display Stop (600),
Stopped by Tracer (300), Low-
Ambient Run Inhibit (200), and Ice-
Building complete (101).
Water Pump Power Supply
Provide power-supply wiring with
fused disconnect switch(es) for the
chilled-water pump(s).
Interconnecting Wiring
Chilled-Water Flow (Pump) Interlock
The Model RTAC Series R
TM
chiller
requires a field-supplied, control-
voltage contact input through a flow
proving switch (6S56) and an
auxiliary contact (6K51). Connect the
proving switch and auxiliary contact
to (6X1) and (A7-2) or (A7-3). Refer to
the field wiring for details.
Chilled-Water Pump Control
An evaporator water-pump output
relay closes when the chiller is given
a signal to go into the AUTO mode
of operation from any source. The
contact is opened to turn off the
pump in the event of most machine-
level diagnostics, to prevent the
buildup of pump heat.
This evaporator water pump output
relay must be used to control the
chilled water pump and to benefit
from the water pump timer function
at startup and shutdown of the
chiller.This is required when the
chiller is in operation under freezing
conditions, especially if the chilled
water loop does not contain glycol.
Table 12 – Pump Relay Operation
Chiller Mode Relay Operation
Auto Instant close
Ice Building Instant close
Tracer Override Close
Stop TImed Open
Ice Complete Instant Open
Diagnostics Instant Open*
*Exceptions noted in paragraphs following
When going from STOP to AUTO,
the CHWP relay is energized
immediately. If evaporator water
flow is not established in 4 minutes
and 15 seconds, the CH.530 de-
energizes the CHWP relay and
generates a non-latching diagnostic.
If flow returns (for example,
someone else is controlling the
pump), the diagnostic is cleared, the
CHWP is re-energized, and normal
control is resumed.
If evaporator water flow is lost after
it has been established, the CHWP
relay remains energized and a non-
latching diagnostic is generated. If
flow returns, the diagnostic is
cleared and the chiller returns to
normal operation.
In general, when there is either a
non-latching or latching diagnostic,
the CHWP relay is turned off as
though there was a zero-time delay.
Exceptions (see Table 12) whereby
the relay continues to be energized
occur with:
1. A Low Chilled-Water Temperature
diagnostic (non-latching) (unless
also accompanied by an
Evaporator Leaving-Water
Temperature Sensor Diagnostic)
or
2. A starter-contactor interrupt-
failure diagnostic, in which a
compressor continues to draw
current even after commanded to
shut down
or
3. A Loss of Evaporator Water Flow
diagnostic (non-latching) and the
unit is in the AUTO mode, after
initially having proven evaporator
water flow.
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