York YK Style H Operation Manual page 178

VSD Initialization Failed
Upon application of power, all boards go through the initialization process. At this time, memory
locations are cleared, program jumper positions are checked and serial communications links are
established. There are several causes for an unsuccessful initialization as follows:
• The Control Center and the VSD must be energized at the same time. The practice of
pulling the fuse in the Control Center to remove power from the Control Center will create a
problem. Power-up must be accomplished by closing the main disconnect on the VSD cabinet
with all fuses in place. A power interruption to the VSD Logic Board will also generate this
message.
• The eproms must be of the correct version for each VSD board and they must be installed
correctly. The eproms are created as a set, and cannot be interchanged between earlier and
later versions.
• Serial data communications must be established. See VSD – Serial Communications. If
communications between the VSD Logic Board, Harmonic Filter Logic Board, ACC Board and
Control Center Microboard does not take place during initialization, this message will be
generated. The serial communications can be verified by selecting the VSD DETAILS Screen
from the MOTOR Screen and observing the Full Load Amps value. A zero displayed for this
and other VSD parameters, indicates a serial communications link problem.
• If the Harmonic Filter option is included, make sure the Filter Logic Board is not in continuous
reset. This condition is evidenced by the Filter Logic Board's LED's alternately blinking. The
filter can be eliminated as a cause of initialization failure by disconnecting the filter by placing
switch SW1 on the Filter Logic Board in the OFF position and removing the ribbon cable
between the Filter Logic Board and the VSD Logic Boards.
• VSD and Harmonic Filter horsepower ratings do not agree.
VSD – High Phase A Instantaneous Current
This shutdown is generated by the VSD if the motor current in phase "A" exceeds a given limit.
The motor current is sensed by the current transformers on the VSD output pole assemblies and
the signals are sent to the VSD Logic Board for processing. Maximum instantaneous permissible
currents are:
• 351/292 HP equals 771 Amps
• 503/419 HP equals 1200 Amps
• 790/658 HP equals 1890 Amps
If an over current trip occurs, but the chiller restarts and runs without a problem, the cause may
be attributed to a voltage sag on the utility power feeding the VSD that is in excess of the specified
voltage range for this product. Thus is especially true if the chiller was running at, or near full load.
If there should be a sudden dip in line voltage, the current to the motor will increase, since the
motor wants to draw constant horsepower. The chiller Pre-rotation Vanes cannot close quickly
enough to correct for this sudden increase in current, and the chiller will trip on an over current
fault.
If the chiller will not restart, but keeps tripping on this same shutdown, an output pole problem is
the most likely cause. The VSD would require service under these conditions.
If this cycling shutdown occurs 3 times in 90 minutes, the third shutdown becomes a safety
shutdown.
178 Model YK Style H Centrifugal Liquid Chillers with OptiView Control Center