York YR Manual page 84

SECTION 3 - DISPLAY MESSAGES
SYSTEM LOCKOUT DELAY
Anytime the chiller shuts down for any reason, it can-
not be restarted for 2 minutes. This message is dis-
played during that time. This is so the refrigerant in the
system settles and the evaporator and condenser pres-
sure equalize.
RUN MESSAGES
LEAVING CHILLED LIQUID CONTROL
The chiller is running, controlling the Leaving Chilled
Liquid to the Leaving Chilled Liquid Temperature
setpoint. There are no system conditions inhibiting this
operation.
MOTOR-PULLDOWN LIMIT
The Pulldown Demand Limit setpoint timer is in ef-
fect and the compressor motor current is more than or
equal to the Pulldown Demand Current Limit setpoint
value. The slide valve operation is being inhibited as
described in "MOTOR – HIGH CURRENT LIMIT"
message below.
MOTOR - HIGH CURRENT LIMIT
The compressor motor current is being limited by the
Current Limit setpoint. This setpoint is adjustable over
the range of 30% to 100% of the Chiller Full Load
Amps (FLA).
With software versions earlier than C.OPT.05.07.xxx,
when the motor current increases to 98% of the cur-
rent limit setpoint, a load inhibit is imposed for 10
seconds, then released. If it increases to 100% of the
setpoint, a load limit is imposed. If it reaches 103% of
the setpoint, a pulsed unload is applied. If the current
increases to 104% of the setpoint, a continuous unload
signal is applied until it falls below 104%, whereupon
a pulsed unload is applied until it falls below 102%
of the setpoint, where a load inhibit is imposed once
more. When it falls below 98% of the setpoint, load
inhibiting is released for normal control.
With software version C.OPT.05.07.xxx (and later),
proportional slide valve loading/unloading is applied
within a band around the Current Limit setpoint. The
proportional load limiting band will begin at 93% of
motor current limit setpoint and end at 100% of the
motor current limit setpoint. While in this band, the
load pulses will be proportionally decreased as the mo-
tor current increases from 93% to 100% of the motor
84
current limit setpoint, and proportionally increased as
the motor current decreases from 100% to 93% of the
motor current limit setpoint. At 100% of the motor
current limit setpoint, no loading or unloading occurs.
The proportional unloading band begins above 100%
of the motor current limit setpoint and ends at 104% of
motor current limit setpoint. While in this band, the un-
load pulses will proportionally decreased as the motor
current decreases from 104% to 100% of the current
limit setpoint and proportionally increased as the mo-
tor current increases from 100% to 104% of the current
limit setpoint. Above 104% of the motor current limit
setpoint, the load output is continuously energized.
To allow field calibration of the CM-2 Board, pressing
the slide valve load keypad key in SERVICE access
level starts a 10-minute timer during which the current
limited thresholds are elevated as follows:
• Load inhibit on rise equals 107% of setpoint
• Start unload on rise equals 110% of setpoint
MAXIMUM LOAD - LOAD LIMIT
Displayed if the special Maximum Load Limit setpoint
is limiting the slide valve loading. This special setpoint
is used to prevent overloading the Oil Separator on
certain compressor/chiller combinations operating at
extreme conditions. After 3 minutes of compressor op-
eration, it limits the compressor motor current to 60%
to 100% (as programmed) until the Leaving Chilled
Liquid Temperature is less than 50.0ºF to 70.0ºF (as
programmed). The slide valve operation is inhibited as
described in description of "MOTOR – HIGH CUR-
RENT LIMIT". Service Technicians refer to OptiV-
iew Control Center Service Instructions (Form 160.81-
M1).
MINIMUM LOAD - LOAD LIMIT
Displayed while slide valve unloading is being limited
by the Minimum Load Control feature. The minimum
allowed slide valve position is that which will maintain
the motor current above the programmed value (15%
to 70% FLA). When the slide valve unloads to the
point the motor current decreases to the setpoint value,
further unloading is inhibited. If it unloads to the point
where the motor current is less than the setpoint, a 1
second load pulse is applied every 3 seconds until the
motor current is more than or equal to the Minimum
Load FLA setpoint value. Service Technicians refer to
YORK Service Manual 160.81- M1.
FORM 160.81-O1 (1020)
ISSUE DATE 10/05/2020
JOHNSON CONTROLS