Interconnecting Wiring - Trane CGAM Installation & Operation Manual

Installation - Electrical

Interconnecting Wiring

Chilled Water Flow (Pump) Interlock
All CGAM model chillers have a factory-installed flow
switch. In addition, it is recommended to use an additional
field-supplied control voltage contact input through an
auxiliary contact to prove flow. Connect the auxiliary
contact to 1X5-3 and 1X5-9. Refer to the field wiring for
details.The auxiliary contact can be a BAS signal, starter
contactor auxiliary or any signal which indicates the pump
is running.
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.
The relay output from 1A9 is required to operate the
EvaporatorWater Pump (EWP) contactor. Contacts should
be compatible with 115/240 VAC control circuit. 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 to open in
an adjustable (usingTechView) 0 to 30 minutes.The non-
AUTO modes in which the pump is stopped, include Reset,
Stop, External Stop, Remote Display Stop, Stopped by
Tracer, Start Inhibited by Low AmbientTemp, and Ice
Building complete.
t
NOTICE:
Equipment Damage!
If the microprocessor 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 always be running when called upon by the chiller
controls.
Table 36. Pump Relay Operation
Chiller Mode
Auto
Ice Building
Tracer Override
Stop
Ice Complete
Diagnostics
When going from Stop to Auto, the EWP relay is energized
immediately. If evaporator water flow is not established in
4 minutes and 15 seconds, the CH530 de-energizes the
72
Relay Operation
Instant close
Instant close
Close
Timed to Open
Instant Open
Instant Open
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 relay is re-energized, and
normal control resumed.
If evaporator water flow is lost once it has 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.
NOTICE:
Equipment Damage!
Do NOT enable/disable the chiller by removing water
flow or equipment damage can occur.
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.The relay continues to be energized with:
A Low Chilled WaterTemperature diagnostic (non-
latching) unless also accompanied by an Evap Leaving
WaterTemperature Sensor Diagnostic.
or
A Loss of EvaporatorWater Flow diagnostic (non-latching)
and the unit is in the AUTO mode, after initially having
proven evaporator water flow.
Note: If pump control is used for freeze protection then
the pump MUST be controlled by the CGAM CH530
control. If another method of freeze protection is
used (i.e. glycol, heaters, purge, etc) then the pump
may be controlled by another system.
Chilled Water Pump Control - Field
Supplied Dual Pumps
CH530 can provide pump control for two customer-
supplied pumps, as long as the pump contactor coils 1A9
and connect the pump fault feedback signals 1A12 are
properly connected.
In this situation, the unit will leave the factory with
Evaporator Pump Control (EVPC) = No Pump Control
(Pump Request Relay) (NPMP) and Evaporator Pump Fault
Input (EVFI) = Installed (INST).When the contactors and
pumps are set up in the field, the CH530 ServiceTool
(TechView) must be used to reconfigure to Evaporator
Pump Control = Dual Pump Fixed Speed and Evaporator
Pump Fault Input = Not Installed or Installed depending on
how the fault feedback wire is connected. It is strongly
recommended to install the Fault Input if possible as the
controls will "hot-swap" the pumps upon detection of a
fault, and may avoid the inevitable Flow Loss diagnostic
(and unit shutdown) that will result if there is no fault
feedback.
CG-SVX17E-EN