Interconnecting Wiring; Chilled Water Pump Control - Trane R Series Installation, Operation And Maintenance Manual

Installation - Electrical
NOTICE:
Equipment Damage!
Control panel main processor does not check for loss of
power to the heat tape nor does it verify thermostat
operation. A qualified technician must verify power to
the heat tape and confirm operation of the heat tape
thermostat to avoid catastrophic damage to the
evaporator.
A convenience outlet is also optional, which shares the
same power supply as the heaters on 140-250 ton units. Be
aware that when the heater is operating, the convenience
outlet amperage draw will be reduced accordingly.
Note: The convenience outlet is optional.The heaters are
required.

Interconnecting Wiring

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 build up of pump heat.
NOTICE:
Equipment Damage!
If insufficient concentration or no glycol is used, the
evaporator water pumps must be controlled by the
CH530 to avoid severe damage to the evaporator due to
freezing. A power loss of 15 minutes during freezing
can damage the evaporator. It is the responsibility of
the installing contractor and/or the customer to ensure
that a pump will start when called upon by the chiller
controls.
Please consult Table 27, p. 54
of glycol.
The warranty will be void, in case of freezing due to the
lack of use of either of these protections.
The relay output from 1U10 is required to operate the
EvaporatorWater Pump (EWP) contactor. Contacts should
be compatible with 115/240 VAC control circuit.The EWP
relay operates in different modes depending on CH530 or
Tracer commands, if available, or service pumpdown (See
maintenance section). Normally, the EWP 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 (usingTechView)
0 to 30 minutes.The non-AUTO modes in which the pump
is stopped, include Reset (88), Stop (00), External Stop
RTAC-SVX01J-EN
for correct concentration
(100), Remote Display Stop (600), Stopped byTracer (300),
Low Ambient Run Inhibit (200), and Ice Building complete
(101).
Regardless of whether the chiller is allowed to control the
pump on a full-time basis, if the MP calls for a pump to start
and water does not flow, the evaporator may be damaged
catastrophically. It is the responsibility of the installing
contractor and/or the customer to ensure that a pump will
start when called upon by the chiller controls.
Table 41. 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 flow is not established in
20 minutes (for normal transition) or 4 minutes, 15
seconds (for pump commanded ON due to an override
safety), 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 WaterTemp. 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 EvaporatorWater Flow diagnostic (non-latching)
and the unit is in the AUTO mode, after initially having
proven evaporator water flow.
87