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FORM QTC4-NM1
ISSUE DATE: 4/2/2018
Both evaporator heater outputs will always be turned
ON and OFF together. An under voltage condition will
keep the heater OFF until full voltage is restored to the
system.
Compressor Heater Control
Each compressor has its own heater. The purpose of
the heater is to assure refrigerant does not condense
in the compressor. There is no oil sump, but refriger-
ant could possibly condense in the rotors or the motor
housing. The heater will be OFF whenever the respec-
tive compressor is running. As soon as the compressor
shuts OFF, the heater will turn ON as long as all motor
temperature sensors in the compressor read less than
70°C (158°F). The heater will turn OFF, if any internal
compressor motor temperature sensor reads more than
71.1°C (160°F).
Alarms
Each system has its own alarm. The Alarm output is ON
(dry contact closed) when no fault condition is pres-
ent and OFF (dry contact open) to indicate an alarm
situation. The Alarm will be activated (contacts open),
if any of the following are true.
• A System is faulted or inhibited from starting for
more than 5 seconds.
• The Unit is faulted or inhibited from starting for
more than 5 seconds.
• A System is locked out.
• The Unit is locked out.
• Power is removed from the chiller.
Chiller Run Contact
The Chiller Run dry contact is closed whenever any sys-
tem is running. It is open when all systems are shut OFF.
Flow Switch Control
A chilled liquid flow switch of suitable type MUST
be connected between Terminals 2 and 13 of 1TB to
provide protection against loss of liquid flow, which
will cause evaporator freeze-up if the chiller is permit-
ted to run.
Remote Run / Stop
A Remote Run/Stop input is available for each system.
QUANTECH
BASIC OPERATING SEQUENCE
Start Sequence and Loading
To initiate the start sequence of the chiller, the follow-
ing conditions must be satisfied before the precharge
of the DC Bus will take place:
• UNIT SWITCH must be ON.
• At least one System Switch is ON
• Run permissive inputs (Remote Cycling
Contacts) must be closed.
• No unit faults exist.
• No unit start inhibits exist.
• At least one system not faulted or inhibited.
• The Daily Schedule is calling for the chiller to
run.
• The Flow Switch is closed.
• Leaving Chilled Liquid Setpoint is above the
Setpoint plus CR (Setpoint High Limit).
Once the precharge takes place, if the anti-recycle tim-
er is timed out the chiller control system on the Chiller
Control Board will select the number of compressors
to start and begin operation of the compressors. The
compressor(s) speed will be ramped to the minimum
start frequency and increase speed as needed in an ef-
fort to regulate the leaving chilled liquid temperature
to meet the desired Setpoint. Unit Warnings
UNIT WARNING
Unit Warning Operation
Unit warnings are caused when a condition is pres-
ent requiring operator intervention to restart the unit.
All setpoints, program values, and options should be
checked before operating the unit. Warnings are not
logged to the history buffer. If a unit warning is in
effect, the message will be displayed to the operator
when the STATUS key is pressed.
Low Battery Warning
The LOW BATTERY WARNING can only occur at
unit power-up. On micropanel power-up, the RTC bat-
tery is checked to see if it is still operational. If it is,
normal unit operation is allowed. If the battery volt-
age is determined to be low, the following warning
message is displayed indefinitely.
UNIT WARNING: !! LOW BATTERY !!
CHECK SETPOINTS/PROGRAM/OPTIONS/TIME
SECTION 7 - OPERATION
97
7
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