York YK Style H Operation Manual page 183

VSD – Harmonic Filter – Precharge – Low DC Bus Voltage
(575V/60 Hz applications)
If the DC Link Voltage does not reach at least 60 VDC (within 100 milliseconds) or at least 630
VDC (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 60 VDC 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 450 VDC. These capacitors are
wired in series to achieve a 900 VDC 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.
VSD – Harmonic Filter-DC Bus Voltage Imbalance
(575V/60 Hz applications)
If the Half DC Link Voltage does not remain within plus or minus 63 VDC 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 and 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.
Model YK Style H Centrifugal Liquid Chillers with OptiView Control Center 183