38 RTAC-SVX002A-EN
Tab. IV-01 – 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
NOTE: Exceptions are listed below.
When going from Stop to Auto, the
EWP relay is energized immediately. If
evaporator water ow is not established
in 4 minutes and 15 sec., the CH530 de-
energizes the EWP relay and generates
a non-latching diagnostic. If ow returns
(e.g. someone else is controlling the
pump), the diagnostic is cleared, the
EWP is re-energized, and normal control
resumed.
If evaporator water ow is lost once it
had been established, the EWP relay
remains energized and a non-latching
diagnostic is generated. If ow 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 EWP
relay is turned off as though there was a
zero time delay. Exceptions (see above
table) whereby the relay continues to be
energized occur with:
A Low Chilled Water Temp. diagnostic
(non-latching) (unless also accompanied
by an Evap Leaving Water Temperature
Sensor Diagnostic)
or
A starter contactor interrupt failure
diagnostic, in which a compressor
continues to draw current even after
commanded to have shutdown
or
A Loss of Evaporator Water Flow
diagnostic (non-latching) and the unit is
in the AUTO mode, after initially having
proven evaporator water ow.
Alarm and Status Relay Outputs
(Programmable Relays)
A programmable relay concept provides
for enunciation of certain events or states
of the chiller, selected from a list of likely
needs, while only using four physical
output relays, as shown in the eld wiring
diagram. The four relays are provided
(generally with a Quad Relay Output
LLID) as part of the Alarm Relay Output
Option. The relay’s contacts are isolated
Form C (SPDT), suitable for use with
120 VAC circuits drawing up to 2.8 amps
inductive, 7.2 amps resistive, or 1/3 HP
and for 240 VAC circuits drawing up to
0.5 amp resistive.
The list of events/states that can be
assigned to the programmable relays
can be found in Table. The relay will be
energized when the event/state occurs.
Installation Electrical
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