York YK-EP, Operation And Maintenance Manual

Page: 207 / 268

Harmonic Filter – High Phase A Current
The maximum instantaneous Harmonic Filter current is monitored and compared to a preset limit.
If this limit is exceeded, a shutdown is performed and this message is generated. The filter current
is monitored using two DCCT’s and these signals are processed by the Filter Logic Board. The
preset limits are as follows:
• 351/292 HP equals 356 Amps
• 503/419 HP equals 496 Amps
• 790/658 HP equals 745 Amps
• 1048/917 HP equals 385 Amps
If the VSD automatically restarts after this shutdown and continues to operate properly with the
filter operating, it is likely the filter tripped due to a sag or surge in the voltage feeding the VSD. If
this message reoccurs, preventing the chiller from starting, the VSD will require service.
Harmonic Filter – High Phase B Current
See Harmonic Filter – High Phase A Current message above.
Harmonic Filter – High Phase C Current
See Harmonic Filter – High Phase A Current message above.
Harmonic Filter – Phase Locked Loop
This shutdown indicates that a circuit called Phase Locked Loop on the Filter Logic Board has lost
synchronization with the incoming power line. This is usually indicative of an open fuse in one of
the filter’s incoming power line. Filter power fuses 11FU, 12FU and 13FU should be checked.
Harmonic Filter – Precharge – Low DC Bus Voltage
During pre-charge, the Filter’s DC link must be equal to or greater than 50VDC (41VDC for 50 Hz)
within 1/10 second after the pre-charge relay is energized. If this condition is not met, a shutdown
is performed and this message is generated.
VSD – Harmonic Filter-Precharge-Low DC Bus Voltage
(575V/60 Hz applications)
If the DC Link Voltage does not reach at least 60VDC (within 100 milliseconds) or at least 630VDC
(within 5 seconds) after the filter precharge command has been received, this shutdown is
performed.
Harmonic Filter – Low DC Bus Voltage
The Harmonic Filter generates its own Filter DC link Voltage by switching its IGBT’s. This DC level
is actually higher than the level that one could obtain by simply rectifying the input line voltage.
Thus, the Harmonic Filter actually performs a voltage BOOST function. This is necessary in order to
permit current to flow into the power line from the filter when the input line is at its peak level. This
shutdown occurs when the Filter’s DC Link Voltage decreases to a level less than 60VDC below the
Filter DC Link Voltage setpoint. This Setpoint is determined by the Filter Logic Board via the sensing
of the three phase input line-to-line voltage. This setpoint is set to the peak of the sensed input line-
to-line voltage plus 32 volts, not to exceed 760 volts and it varies with the input line-to-line voltage.
If this shutdown occurs occasionally, the likely cause is a severe sag in the input line voltage.
Harmonic Filter – DC Bus Voltage Imbalance
The Filter DC link is filtered by large, electrolytic capacitors, rated for 450VDC. These capacitors are
wired in series to achieve a 900VDC capability for the DC link. It is important the voltage is shared
equally from the junction of the center or series capacitor connection, to the negative bus and to
the positive bus. This center point should be approximately ½ of the total DC Link Voltage.
207 YK-EP Style B Centrifugal Chiller