York YK-EP Operation And Maintenance Manual page 212

Oil – Differential Pressure Calibration
The Sump and Pump oil pressure transducers indicated a differential oil pressure of greater than
15.0 PSID during the oil pressure transducer Auto-Zeroing period 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 pressure 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 conditions have occurred while in System Prelube, System Run or System Coastdown. The
chiller can be started after the Operator presses the WARNING RESET button. This safety shutdown
is not performed when the Refrigerant Selection (microboard SW1-1) is set to "R22".
• 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-
• 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 applicable coastdown period (240 seconds Default; adjustable 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 restart 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 Control Center is configured for auto-restart
or manual restart after power failure by a qualified Service Technician 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 imbalance is not checked until the chiller has been running for at least 45 seconds
and the average of the three phases of motor current is greater than 80% of the programmed 100%
chiller Full Load Amps. The average is calculated as:
The imbalance is calculated as:
The Style B Solid State Starter and Variable Speed Drive detects the unbalance condition and advise
the OptiView Control Center Microboard via serial communications. The Style A Solid State Starter
and Variable Speed Drives returns the 3-phase motor current values to the OptiView Control Center
212
(Ia+Ib+Ic)
Iave =
3
(Ia-Iave)+(Ib-Iave)+(Ic-Iave)
2(Iave)
x 100
YK-EP Style B Centrifugal Chiller