York YK-EP, Operation And Maintenance Manual

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VSD – Harmonic Filter-DC Bus Voltage Imbalance
If the Half DC Link Voltage does not remain within plus or minus 63VDC of the DC Link Voltage
divided by 2, this shutdown is performed.
Harmonic Filter – Input Current Overload
The three phases of RMS Filter current are monitored. If any one of the three phases continuously
exceeds a given threshold for 7 seconds, a chiller shutdown is performed and this message is
displayed. The maximum permissible continuous RMS current ratings for the Harmonic Filter are:
• 351/292 HP equals 128 Amps
• 503/419 HP equals 176 Amps
• 790/658 HP equals 277 Amps
• 1048/917 HP equals 385 Amps
Harmonic Filter – Logic Board Power Supply
The low voltage power supplies on the Filter Logic Board have decreased below their permissible
operating range. The Filter Logic Board receives its power from the VSD Logic Board via the ribbon
cable, connecting the two boards.
Harmonic Filter – Run Signal
When a digital run command is received at the Filter Logic Board from the VSD Logic Board via
the 16 position ribbon cable, a 1/10 second timer is started. If a redundant run command does
not occur on the serial data link from the VSD Logic Board before the timer expires, a shutdown is
performed and this message is generated.
Harmonic Filter – DC Current Transformer 1
During initialization, with no current flowing through the DC Current Transformers (DCCT’s), the
DCCT output voltages are measured and compared with a preset limit via the Filter Logic Board. If
the measured values exceed the preset limits, the DCCT’s are presumed to be defective and this
shutdown is generated.
Harmonic Filter – DC Current Transformer 2
See Harmonic Filter – DC Current Transformer 1 message above.
Safety shutdown messages
Evaporator – Low Pressure
The Evaporator Pressure, as sensed by the Evaporator transducer, has decreased to the safety
shutdown threshold. For water cooling applications, the safety shutdown threshold is a fixed value
for the respective refrigerant. For Brine cooling applications, the safety shutdown threshold varies
according to the concentration of the Brine solution. The Brine shutdown threshold is programmed
at the YORK Factory. It should not be changed by anyone other than a qualified Service Technician
following instructions in OptiView Control Center – Service Instructions (Form 160.54-M1) . The chiller
can be started after the Evaporator Pressure increases to the restart threshold and the Compressor
Switch is placed in the Stop-Reset (O) position.
YK-EP Style B Centrifugal Chiller 208