JOHNSON CONTROLS
116
FORM 160.69-O1
ISSUE DATE: 9/30/2012
SECTION 2 – OPTIVIEW CONTROL CENTER
When a soft shutdown is initiated on the entire chiller,
a close command is applied to the Pre-rotation Vanes.
If both compressors are running, a Vanes close com-
mand is applied simultaneously to both compressors.
When the Vane Motor Switch for each compressor
closes, indicating its vanes have closed (or 3.5 min-
utes have elapsed, whichever occurs first), a close
command is applied to the Discharge Valve for the
respective compressor. When the Discharge Valve
limit switch closes, indicating the valve has closed (or
40 seconds have elapsed, whichever occurs first), the
chiller enters “Coastdown”. If both compressors are
running, the chiller will enter “Coastdown” only after
both Discharge Valves have closed or timed out.
While the Vanes are closing during a soft shutdown, if
a Local stop or any faults listed above occur, the soft
shutdown is terminated and the chiller immediately
enters “Coastdown”.
Run Messages
“LEAVING CHILLED LIQUID CONTROL”
The chiller is running, controlling the Leaving Chilled
Liquid to the Leaving Chilled Liquid Temperature Set-
point. There are no system conditions inhibiting this
operation.
“LEAD MOTOR-PULLDOWN LIMIT”
(Software version C.OPT.01.02B. xxx (and earlier))
The Chiller Pulldown Period is in effect and the com-
pressor motor current is being limited to the pro-
grammed Pulldown Demand Limit Setpoint. The
Chiller Pulldown Period is in effect from the instant
the chiller enters “System Run” until the Leaving
Chilled Liquid Temperature is within 2ºF of the Leav-
ing Chilled Liquid Temperature Setpoint. Refer to
Electro-mechanical Starter Screen for detailed descrip-
tion of the Chiller Pulldown Demand Limit Setpoint.
The Pre-rotation vanes are controlled to limit motor
current as described under “Lead Compressor-High
Current Limit” message below.
"System In Lead Compressor Pulldown"
(Software Version C.OPT.11.03.01.004 (and later)
Displayed while a LEAD COMPRESSOR PULL-
DOWN TIME Setpoint (0-255 minutes) is in effect.
The time remaining in the period is also displayed. For
the duration of this period, only the Lead compressor
will be permitted to run. The Lag compressor will not
be brought on line during this period. A current limit
may be applied to the Lead motor during this period
using the LEAD COMPRESSOR PULLDOWN DE-
MAND LIMIT setpoint (30-100%). Refer to complete
explanation in SECTION 1 of this book.
“LEAD MOTOR-HIGH CURRENT LIMIT”
With software version C.OPT.11.02B .xxx (and ear-
lier), the Chiller Steady State Period is in effect and
the lead compressor motor current is being limited by
the Chiller Current Limit Setpoint. The Chiller Steady
State Period begins after the Chiller Pulldown Period
ends and remains in effect until the chiller is shutdown.
With software version C.OPT.11.03.01.004 (and later),
either the Lead Compressor Pulldown Demand Time
Setpoint is in effect and the lead compressor motor
current is being limited by the Lead Compressor Pull-
down Demand Limit Setpoint or the Lead Compressor
Pulldown Demand Time Setpoint has elapsed and the
lead compressor motor current is being limited by the
Chiller Current Limit Setpoint.
Refer to the MOTOR screen for details of the condi-
tions above.
When the motor current increases to the “inhibit open”
threshold, the Pre-rotation Vanes are inhibited from
further opening. This prevents a further current rise. If
the current continues to rise to the “start close” thresh-
old, the Vanes begin closing until the current falls to
the “stop close” threshold. Automatic Vane opera-
tion is resumed and this message automatically clears
when the motor current decreases to the “allow open”
threshold. To allow field calibration of the CM-2 Cur-
rent Module, pressing the Pre-rotation Vanes OPEN
key in Service access level, starts a 10 minute timer
during which the current limit thresholds are elevated.
Refer to table below:
VANE CONTROL
MOTOR CURRENT (%FLA)
ELECTRO-
MECHANICAL/
STARTER
SERVICE
MODE
On rise, inhibit open
100
107
On fall, allow open
98
106
On rise, start close
104
110
On fall, stop close
102
109
“LAG COMPRESSOR PRELUBE”
A start has been initiated on the lag compressor and
the 50 second pre-start lubrication is being performed.
