York YZ MODEL A, Руководство по эксплуатации и обслуживанию

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JOHNSON CONTROLS
23
SECTION 2 - SYSTEM OPERATING PROCEDURES
FORM 161.01-OM1
ISSUE DATE: 6/8/2018
2
Automatic Temperature Restart
This setting defines the temperature offset above the
LCHLT setpoint where automatic restart is expected. It
is programmable over a range of 0°F to 46 °F (-17.8 °C
and 7.8 °C) varying with the LCHWT setpoint. How-
ever, the restart temperature will never be calculated
above 82°F. This setpoint can be used to reduce chiller
cycling by delaying the chiller restart until the cooling
load has increased sufficiently.
OPERATOR SETPOINTS QUICK REFERENCE
The most common Operator level setpoints can be
found on the Setpoints screen or the following screens:
TABLE 3 - INPUT CURRENT LIMIT THRESHOLD
SCREEN NAME SETPOINT
Home > Evaporator
Local Cooling Setpoint
Temperature
Home > Evaporator
Shutdown
Temperature Offset
Home > Evaporator
Restart
Temperature Offset
Home > Motor
Local Motor Current Limit
Home > Motor Pulldown Demand Limit
Home > Motor Pulldown Demand Time
Home > Condenser > Head
Pressure Control
Head Pressure Control
2
TABLE 2 - TEMPERATURE SETPOINT
CONTROL
SOURCE
LEAVING CHILLED LIQUID TEMPERATURE SETPOINT
Local
Local Leaving Chilled Liquid Temperature Setpoint, entered from the panel. It is programmable over
the range of 36.0°F to 72.0°F (2.2°C to 22.2 °C) (water) or 10.0°F to 72.0°F (-12.2 °C to 22.2 °C)
(brine).
Building
Automation
Systems (BAS)
Remote Leaving Chilled Liquid Temperature Setpoint value sent over communications 36.0°F to 72.0°F
(2.2°C to 22.2 °C) (water) or 10.0°F to 72.0°F (-12.2 °C to 22.2 °C) (brine). If nothing is written to the
address, the default is 45 °F (7.2 °C).
Hardwire
The Remote Setpoint Minimum is user selectable at the Operator password level between 0.0°F and
200.0°F (-17.8 °C and 93.3 °C) (default = 0.0°F (-17.8 °C)). The Remote Setpoint Maximum is also
user selectable between 0.0°F and 200.0°F (-17.8 °C and 93.3 °C) (default = 100.0°F (37.8 °C)). The
Setpoint will vary over the range selected by the Min and Max by the proportion of the Hardwire Analog
0 to 10VDC or 4 to 20mA signal from the BAS controller. For example: with the Min set to 40 and
the Max to 60 and the BAS 0 to 10VDC control signal sending a 5VDC signal, the Selected Cooling
Setpoint will be 50.0°F (10 °C).
Pulse Width
Modulation
(PWM)
The Remote Setpoint Minimum is user selectable at the Operator password level between 0.0°F and
200.0°F (-17.8 °C and 93.3 °C) (default = 0.0°F (-17.8 °C)). The Remote Setpoint Maximum is also
user selectable between 0.0°F and 200.0°F (-17.8 °C and 93.3 °C) (default = 100.0°F (37.8 °C)). The
Setpoint will vary over the range selected by the Min and Max by the proportion of the timed 1 to 11
second pulse. For example: with the Min set to 40 and the Max to 60 and the BAS closing a contact
between TB3-19 and TB3-1 for 6 seconds, the Selected Cooling Setpoint will be 50.0°F (10 °C).
The PWM input is in the form of a 1 to 11 second relay contact closure that applies 115VAC to the I/O
Board TB3-19 for 1 to 11 seconds. A contact closure time (pulse width) of 1 second produces a 0°F
offset form the Min Setpoint. An 11 second closure produces the maximum offset. The relay contacts
should close for 1 to 11 seconds at least once every 30 minutes to maintain the setpoint to the desired
value. If a 1 to 11 second closure is not received within 30 minutes of the last closure, the setpoint
reverts to the Min setpoint valve. A closure is only accepted at rates not to exceed once every 70 sec-
onds