Trane CITY RTSF Series Manual page 23

Interconnecting Wiring (Field Wiring Required)
Important: Do not turn chiller on or off using the chilled water pump interlocks.
When making fi eld connections, refer to the appropriate fi eld layout, wiring, schematics and controls diagrams that
ship with the unit. Whenever a contact closure (binary output) is referenced, the electrical rating is:
At 120 VAC
At 240 VAC
Whenever a dry contact input (binary input) is referenced, the electrical rating is 24VDC, 12 mA.
Whenever a control voltage contact input (binary input) is referenced, the electrical rating is 120 VAC, 5mA.
Some connections require the user to provide an external source of power. The 110V control power transformer is not
sized for additional load.
Chilled Water Pump Control
Tracer UC800 has a evaporator water pump output relay that 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. To protect against the build-up of pump heat for those
diagnostics that do not stop and/or start the pump and to protect against the condition of a bad fl ow switch, the
pump shall always be stopped when refrigerant pressure is seen to be close to heat exchanger design pressure.
Chilled Water Flow Interlock
Tracer UC800 has an input that will accept a contact closure from a proof-of-fl ow device such as a fl ow switch.
The fl ow switch is to be wired in series with the chilled water pump starter's auxiliary contacts. When this input
does not prove fl ow within 20 minutes relative to transition from Stop to Auto modes of the chiller, or if the fl ow is
lost while the chiller is in the Auto mode of operation, the chiller will be inhibited from running by a non-latching
diagnostic. The fl ow switch input shall be fi ltered to allow for momentary openings and closings of the switch due
to turbulent water fl ow. This is accomplished with a 6 seconds fi ltering time. The sensing voltage for the condenser
water fl ow switch is 115/240 VAC.
IMPORTANT! DO NOT cycle the chiller through starting and stopping the chilled water pump. This could cause
the compressor to shut down fully loaded. Use the external stop/start input to cycle the chiller.
Condenser Water Pump Control
Tracer UC800 provides a contact closure output to start and stop the condenser water pump. It will allow to run the
condenser pump after compressor stop to avoid risk of freezing due to refrigerant migration from evaporator.
Condenser Water Pump Prestart time has been added to help with cold condenser water problems. In very cold
outdoor ambient, the cooling device's sump would reach the chiller some time after the low system differential
pressure protection had run through its ignore time, and result in an immediate shutdown and latching diagnostic.
By simply starting the pump earlier, and allowing mixing of the warmer indoor loop with the cooling device's sump,
this problem can be avoided.
RLC-SVX023B-GB
7.2 amp resistive
2.88 amp pilot duty
250 W, 7.2 FLA,
43.2 LRA
5.0 amp resistive
2.0 amp pilot duty
250 W, 3.6 FLA,
21.3 LRA
Installation - Electrical
23