York YK-EP, Operation And Maintenance Manual

Page: 72 / 268

Table 59: Display only
Field/LED name Description
Stall Count
Displays the number of times that the system had detected an
Economizer Compressor Stall.
Stall Time
Displays the accumulated time that the Stall Detector Board output
is greater than the High Limit Setpoint voltage while the chiller is
running.
VGD Control State
Shows the current state of the VGD Control. It will show various
messages as follows:
• Undefined
• Disabled
• Stall Waiting
• Probing
• Stall Reacting
• PRV Override
• Sensor Failure Override
• Extreme Stall Override
• Manual Hold
• Manual Open
• Manual Close
• Inactive
Table 60: Programmable
Button Access level Description
Extreme Stall
Duration
Service
(10 to 20 minutes; default 10 minutes.)
The Extreme Duration override occurs when the Variable Geometry
Diffuser (VGD) stall voltage is two times higher than the high limit
for longer than 10 minutes. At this time, the VGD will be opened and
a warning message displayed. The VGD will remain open until the
warning is manually cleared by the operator. Once cleared, the VGD
Control will return to normal operation.
PRV VGD
Inhibit
Service
(40 to 100%, Default 95%)
If PRV position is greater than the PRV VGD Inhibit (95%), the VGD
will open in pulse mode just the same way as in the Probing state.
PRV Offset Service
(0 to 5%, Default 3%)
When VGD control enters the Wait State, the PRV position is PRV
wait Start position. During the Wait state, if PRV position is greater
than the PRV wait Start + 3%, the VGD control will enter the Probing
state.
YK-EP Style B Centrifugal Chiller 72