York YCIV Series, Установка, эксплуатация и обслуживание

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JOHNSON CONTROLS
197
FORM 201.23-NM2
ISSUE DATE: 09/25/2020
7
OPERATING CONTROLS
Anti-recycle Timer
A typical 5 minute or 10 minute anti-recycle timer is not
necessary to allow compressor motor cooling, due to
the VSD’s ability to provide a low current inrush start.
The system does utilize a fixed 120 second anti-recy-
cle timer to prevent short cycling of systems and to al-
low positioning the Feed and Drain Valves to a zero
(closed) position by the Flash Tank Drain and Feed
Valve Controller in the event of a power failure.
On power-up of the control panel, the anti-recycle tim-
er for each system will be set to 120 seconds and must
time out before a compressor is allowed to start.
Whenever a system starts, the anti-recycle timer for all
systems will be set to 120 seconds and will count down
from the time the motor starts. The timer must time out
before another compressor is allowed to start.
Whenever a system shuts down, the anti-recycle timer
for that system will be set to 120 seconds. The timer
must time out before the system is allowed to restart.
Evaporator Pump Control
The evaporator pump dry contacts are energized when
any of the following conditions are true:
• If a Low Leaving Chilled Liquid Fault occurs.
• Whenever a compressor is running.
• The Daily Schedule is ON and the UNIT switch
is ON.
Even if one of above is true, the pump will not run if
the panel has been powered up for less than 30 seconds
or if the pump has run in the last 30 seconds to prevent
pump motor overheating.
Evaporator Heater Control
The evaporator heater is controlled by ambient
air temperature. If no systems are running and the
ambient temperature drops below 40°F, the heater is
turned on. If no systems are running and the tempera-
ture rises above 45°F the heater is turned off. Whenever
a system is running, the evaporator heater is turned off.
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.
Pumpdown Control
The VSD assures a smooth slow compressor start. As a
result of this, neither pumpdown on start-up or pump-
down on shutdown is required. The Drain and Feed
Valves will close when a compressor stops. This is a
similar to a liquid line solenoid valve closing on a con-
ventional chiller.
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 refrigerant could
possibly condense in the rotors or the motor housing.
The heater will be off whenever the respective com-
pressor 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 than158°F. The
heater will turn off, if any internal compressor motor
temperature sensor reads more than160°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 should be activated (contact
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
system is running. It is open when all systems are shut
off.
SECTION 7 - OPERATION