JOHNSON CONTROLS
131
SECTION 2 – OPTIVIEW CONTROL CENTER
FORM 160.79-O3
ISSUE DATE: 11/09/2018
2
“WARNING – CONDENSER OR VGD #2
SENSOR FAILURE”
The difference between Compressor #2 Stall Pressure
Transducer output and the Condenser Pressure Trans-
ducer output has exceeded 0.28 VDC for 3 continuous
minutes while compressor #2 was running. This fea-
ture verifies the operation of the compressor #2 Stall
transducer and the Condenser transducer. Since both
transducers are measuring essentially the same pres-
sure, both outputs should be within the specified toler-
ance. This message must be manually cleared. It will
be displayed until the transducer outputs are within the
acceptable range of each other and the WARNING RE-
SET key in SERVICE access level.
While this message is displayed, the Variable Geom-
etry Diffuser (VGD) of both compressors are driven
to the full open position (100%) and held there until
this warning is manually is cleared. When cleared, the
VGD of both compressors return to normal operation.
“WARNING – CONDITIONS OVERRIDE VGD
#1”
An extreme stall condition has been detected in com-
pressor #1 while it was running. An extreme stall con-
dition exists when the Stall Detector Voltage (output
of the Stall Detector Board) exceeds twice the HIGH
LIMIT setpoint for the duration programmed in the
EXTREME STALL DURATION Setpoint (10 to 20
minutes). While this message is displayed, compressor
#1 Variable Geometry Diffuser (VGD) is driven to the
full open (100%) position and held there until the mes-
sage is manually cleared. This protects the VGD ring
from possible damage from an extreme stall condition.
This message can be cleared after the Stall Detector
Voltage returns to less than two times the HIGH LIMIT
Setpoint and the WARNING RESET key is pressed in
SERVICE access level.
The Extreme Stall condition is not checked under the
following conditions:
• While the VGD is in Manual control mode
• While the VGD is fully closed (position is 0%)
(VGD Limit Switch closed)
• While the Pre-rotation vanes position is greater
than the PRV VGD INHIBIT Setpoint
“WARNING – CONDITIONS OVERRIDE VGD
#2”
An extreme stall condition has been detected in com-
pressor #2 while it was running. An extreme stall con-
dition exists when the Stall Detector Voltage (output
of the Stall Detector Board) exceeds twice the HIGH
LIMIT setpoint for the duration programmed in the
EXTREME STALL DURATION Setpoint (10 to 20
minutes). While this message is displayed, compressor
#2 Variable Geometry Diffuser (VGD) is driven to the
full open (100%) position and held there until the mes-
sage is manually cleared. This protects the VGD ring
from possible damage from an extreme stall condition.
This message can be cleared after the Stall Detector
Voltage returns to less than two times the HIGH LIM-
IT Setpoint and the WARNING RESET key is pressed
in SERVICE access level.
The Extreme Stall condition is not checked under the
following conditions:
• While the VGD is in Manual control mode
• While the VGD is fully closed (position is 0%)
(VGD Limit Switch closed)
• While the Pre-rotation vanes position is greater
than the PRV VGD INHIBIT Setpoint
“WARNING – HEAD PRESSURE – HIGH HEAD
LAG START LIMIT”
Displayed when starting the Lag compressor while a
high head condition exists. A high head condition ex-
ists when the actual DELTA P/P is greater than the
HIGH HEAD DP/P LIMIT Setpoint. To minimize
surging while starting the lag compressor under this
condition, the lead compressor’s Pre-rotation Vanes
are driven closed coincident with the start of the Lag
compressor’s Pre-lube. They will be allowed to open
after the Lag compressor is running, the Lag Discharge
Valve is open and the Lead and Lag motor currents are
balanced within 5%.
“WARNING – ANTI SURGE – EXCESS SURGE
LIMIT”
This warning applies to dual compressor operation
only. The Pre-rotation Vanes are being load limited
because a surge event has been detected while both
compressors are running. As a surge avoidance, a close
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