Installation - Electrical
The unit is equipped with a control power transformer,
it is not necessary to provide additional control power
voltage to the unit.
All units are factory-connected for appropriate labeled
voltages.
The evaporator shell is insulated from ambient air and
protected from freezing temperatures by two thermo-
statically-controlled immersion heaters and two strip
heaters .Whenever the water temperatures drops to
approximately 37ºF(2.8ºC) ,the thermostat energized the
heaters .The heaters will provide protection from ambi-
ent temperatures down to -4ºF(-20ºC).
It is required to provide an independent power source
(230V 60Hz -15amp) ,with a fused-disconnect.
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The Model RTAG Series chiller requires a
fi
eld-supplied
control voltage contact input through a
fl
ow proving
switch 5B5 and an auxiliary contact 5K9 AUX. Connect
the proving switch and auxiliary contact to 1K14 J2-1
and 1X5-27. Refer to the
fi
eld wiring for details.
The auxiliary contact can be BAS signal, starter contac-
tor auxiliary or any signal which indicates the pump is
running. A
fl
ow switch is still required and cannot be
omitted.
An evaporator water pump output relay closes when the
chiller is given a signal to go into the Auto mode of oper-
ation 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.
The relay output from 1K16 is required to operate the
Evaporator Water Pump (EWP) contactor. Contacts
should be compatible with 115/230 VAC control circuit.
The EWP relay operates in different modes depending
on UC800 or Tracer commands, if available. 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 (using Tracer TU) 0 to 30 minutes.
The non-AUTO modes in which the pump is stopped, in-
clude Reset (88), Stop (00), External Stop (100), Remote
Display Stop (600), Stopped by Tracer (300), Low Ambi-
ent Run Inhibit (200).
When unit stops, if the evaporator inlet and outlet water
temperature is lower than a certain protection set value,
the controller of RTAG will command the water pump
to start to prevent the evaporator from freezing. If cus-
tomer does not allow RTAG unit to control the pump, the
evaporator is at risk of freezing. It is the responsibility of
the installation contractor or customer to ensure that the
water pump is started on when is required by the chiller.
Chiller Mode
Relay Operation
Auto
Instant close
Tracer Override
Close
Stop
Timed Open
Diagnostics
Instant Open
When going from Stop to Auto, the EWP relay is ener-
gized immediately. If evaporator water
fl
ow is not estab-
lished in 4 minutes and 15 sec., the UC800 de-energizes
the EWP relay and generates a non-latching diagnostic. If
fl
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
fl
ow is lost once it had been estab-
lished, the EWP relay remains energized and a non-latch-
ing diagnostic is generated. If
fl
ow returns, the diagnos-
tic is cleared and the chiller returns to normal operation.
In general, when there is either a non-latching or latch-
ing 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 evaporator Leaving Wa-
ter Temperature Sensor Diagnostic) or
A starter contactor interrupts failure diagnostic, in which
a compressor continues to draw current even after com-
manded to have shutdown or
A Loss of Evaporator Water Flow diagnostic (non-latch-
ing) and the unit is in the AUTO mode, after initially
having proven evaporator water
fl
ow.
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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
fi
eld wiring diagram. The four
relays are provided (generally with a Quad Relay Out-
put LLID) as part of the Alarm Relay Output Option. The
RTAG-SVX001H-EN
41
Table 14.