Trane RTAC 140-400 ton units (50 HZ) User Manual

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RTAC-SVX01F-EN

When going from Stop to Auto, the EWP relay is energized immediately. If evaporator 
water flow is not established in 4 minutes and 15 sec., the CH530 de-energizes the 
EWP relay and generates a non-latching diagnostic. If flow 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 flow is lost once it had been established, the EWP 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 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 flow.

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 field 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 

. The relay will be energized when the event/state occurs.

Auto

Instant close

Ice Building

Instant close

Tracer Override

Close

Stop

TImed Open

Ice Complete

Instant Open

Diagnostics

Instant Open

Alarm - Latching

This output is true whenever there is any active diagnostic that requires a manual reset to clear, that 
affects either the Chiller, the Circuit, or any of the Compressors on a circuit. This classification does not 
include informational diagnostics.

Alarm - Auto Reset

This output is true whenever there is any active diagnostic that could automatically clear, that affects 
either the Chiller, the Circuit, or any of the Compressors on a circuit. This classification does not include 
informational diagnostics.

Alarm

This output is true whenever there is any diagnostic affecting any component, whether latching or auto-
matically clearing. This classification does not include informational diagnostics