York YK-EP B Operation & Maintenance Manual page 178

SECTION 3 - DISPLAY MESSAGES
that begins 10 seconds into System Prelube and lasts
for 3 seconds. This is indicative of a defective Sump
or Pump transducer, since the oil pump is not running
during this period and the actual differential oil pres-
sure is 0 PSID. The transducers are sensing the same
pressure during this period and their outputs should be
similar. The chiller can be started after the Operator
presses the WARNING RESET button.
Oil – Variable Speed Pump – Setpoint Not
Achieved
This is only applicable to chillers equipped with the Oil
Pump Variable Speed Drive. One of the following con-
ditions have occurred while in System Prelube, System
Run or System Coastdown. The chiller can be started
after the Operator presses the WARNING RESET but-
ton. This safety shutdown is not performed when the
Refrigerant Selection (microboard SW1-1) is set to
"R22".
1. The differential oil pressure was less than 35.0
PSID for 5 continuous seconds during the last 10
seconds of the System Prelube period or during
the first 15 seconds of System Run.
-OR-
2. Anytime after the first 30 seconds of System Run,
the differential oil pressure was less than the Oil
Pressure Setpoint with the speed command from
the Microboard at 60 Hz for 5 continuous seconds.
Control Panel – Power Failure
A Control Power failure has occurred. If the power
failure duration was less than the duration of the ap-
plicable coastdown period (240 seconds Default; ad-
justable 240 to 900), the remainder of the coastdown is
performed upon restoration of power. The chiller can
be started after the Operator presses the WARNING
RESET button. This message can indicate a Cycling
(auto-restart after power failure) or Safety (manual re-
start after power failure) shutdown, depending upon
Control Center configuration. It indicates a cycling
shutdown when displayed in orange characters; safety
shutdown when displayed in red characters. The Con-
trol Center is configured for auto-restart or manual re-
start after power failure by a qualified Service Techni-
cian following instructions in OptiView Control Center
– Service Instructions (Form 160.54-M1).
Motor Or Starter – Current Imbalance
The three phase compressor motor current imbalance
was greater than 30% continuously for 45 seconds. The
178
imbalance is not checked until the chiller has been run-
ning for at least 45 seconds and the average of the three
phases of motor current is greater than 80% of the pro-
grammed 100% chiller Full Load Amps. The average
is calculated as:
(Ia+Ib+Ic)
Iave =
The imbalance is calculated as:
(Ia-Iave) + (Ib-Iave) + (Ic-Iave)
2(Iave)
The Style B Solid State Starter and Variable Speed
Drive detects the unbalance condition and advise the
OptiView Control Center Microboard via serial com-
munications. The Style A Solid State Starter and Vari-
able Speed Drives returns the 3-phase motor current
values to the OptiView Control Center Microboard
where the unbalance calculation is performed. This
safety shutdown is not performed on Electro-Mechani-
cal Starter applications.
Thrust Bearing – Proximity Probe Clearance
The clearance between the compressor high speed
thrust collar and the tip of the Proximity Probe has in-
creased more than +10 mils or decreased to less than
-25 mils (for 2 continuous seconds) from the Refer-
ence Position. The minimum allowed clearance is 23
mils. Therefore, if the Reference position is less than
47 mils, the shutdown will occur when the actual clear-
ance is less than 22 mils.
The clearance is only checked during the last 20 sec-
onds of System Prelube, during System Run and dur-
ing coastdown. Therefore, the fault is only detected
during those periods.
This shutdown must be evaluated by a
qualified Service Technician prior to
starting the chiller. Starting the chiller
without this evaluation could result in
severe compressor damage. To prevent the
chiller from starting without the proper
evaluation, restart is inhibited until the
clearance is within acceptable limits and a
special reset procedure is performed by the
Service Technician. The evaluation and
reset procedure are contained in Optiv-
iew Control Center - Service Instructions
(Form 160.54-M1).
FORM 160.87-OM1
ISSUE DATE: 8/24/2018
3
x 100
JOHNSON CONTROLS