Johnson Controls York YCAL0014E Series, Инструкция по установке, эксплуатации и обслуживанию

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JOHNSON CONTROLS
105
FORM 150.62-NM6 (103)
2
1. Low Leaving Chilled Liquid Fault
2. Any compressor is running
3. Daily Schedule is not programmed OFF and
Unit Switch is ON
The pump will not run if the micro 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 tem-
perature. When the ambient temperature drops below
40°F (4.4
°C)
the heater is turned on. When the tem-
perature rises above 45°F (7.2
°C)
the heater is turned
off. An under voltage condition will keep the heater off
until full voltage is restored to the system.
PUMPDOwN CONTROL
Each system has a pump-down feature upon shut-off.
Manual pumpdown from the keypad is possible by turning
off the respective system’s switch under the OPTIONS
key. On a non-safety, non-unit switch shutdown, all com-
pressors but one in the system will be shut off. The LLSV
or EEV will also be turned off. The final compressor will
be allowed to run until the suction pressure falls below the
cutout, or for 180 seconds, whichever comes first.
The EEV pilot solenoid is also used as a low super-
heat safety device when the EEV is selected as the
expansion valve type. While the system is running and
not in a pumpdown mode, the EEV pilot solenoid will
close if the suction superheat falls below 4°F. The EEV
pilot solenoid will open again when the superheat rises
above 7.0°F. This safety device is ignored for the first 30
seconds of system run time. If the EEV pilot solenoid is
closed 10 times in 2 minutes on the safety device, the
low superheat safety will be triggered.
ELECTRONIC ExPANSION vALvE (EEv)
General
The EEV is optional on the YCAL0014 - YCAL0080 and
standard on the YCAL0090 - YCAL0114. When the EEV
is installed, it is programmed under Service Mode, which
instructs the micro to control the associated outputs.
The EEV controller in the micro is a PI controller. The
integration time is fixed while gain scheduling varies
the proportional gain based on the superheat error. As
the superheat gets smaller, the proportional gain gets
smaller.
The output of the PI controller may be viewed on the
display and printouts as the EEV output percentage.
This output % is converted to a PWM signal that is used
to control the EEV. It can over and under drive the heat
motor for faster valve response. This PWM output is the
percentage of a 1 second period that the 24VAC heat
motor power signal is energized.
MOP Feature
The controller has an MOP feature that overrides the
superheat control when the MOP setpoint is exceeded.
This is generally only active during hot water starts. The
MOP setpoint is 60°F saturated suction temp.
The MOP feature is also used to prevent undershoot
when the suction temperature of a system being started
is much higher than the return water temperature. This
provides better start-up superheat control for high am-
bient, low water temp start-ups when the superheat
measurement is high due to a warm suction line.
valve Preheat
The heat motor is pre-heated for moderate and low ambi-
ent standby conditions. When the ambient is below 25°F,
the heat motor is preheated to 25%. between 25 and
50°F, the preheat is ramped from 25% to 0% linearly,
preheat at 50°F and above is 0%.
Inputs
Two external inputs to the micro are used to control
the superheat. These inputs are the suction tempera-
ture sensor input and the suction pressure transducer
input.
Outputs
Two output signals are fed to the EEV. The first con
-
trols the EEV pilot solenoid portion of the valve and is
115VAC.
The second output is the EEV PWM signal which feeds
the heat motor. The signal will be a 24VAC pulsed signal
that is fed to the valve heat motor within a 1 second
period. This 24VAC signal can be fed to the motor 0%
to 100% of the 1-second period. The signal is measured
in terms of watts with 100% equating to 30W, 50% to
15W, etc.
The EEV PWM signal is used to overdrive the valve
for faster response. It also allows the valve to stabilize
and control superheat more accurately. This feature is
especially valuable at start and during transients when
valve overfeed could cause liquid to be fed to the
compressor.