York YK-EP B Operation & Maintenance Manual page 171

FORM 160.87-OM1
ISSUE DATE: 8/24/2018
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 seri-
al communications links are established. There are sev-
eral causes for an unsuccessful initialization as follows:
• The Control Center and the VSD must be ener-
gized 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 correct-
ly. The EPROMs are created as a set, and cannot
be interchanged between earlier and later versions.
• Serial data communications must be established.
Refer to VSD – Serial Communications on Page
174. 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 ver-
ified 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 communica-
tions 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 initializa-
tion 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 mo-
tor 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 in-
stantaneous permissible currents are:
JOHNSON CONTROLS
SECTION 3 - DISPLAY MESSAGES
• 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 prod-
uct. 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 10 minutes,
the third shutdown becomes a safety shutdown.
VSD – High Phase B Instantaneous Current
See High Phase A Instantaneous Current message
above.
VSD – High Phase C Instantaneous Current
See High Phase A Instantaneous Current message
above.
VSD – Phase A Gate Driver
A second level of current protection exists on the VSD
driver boards themselves. The collector-to-emitter satu-
ration voltage of each IGBT is checked continuously
while the device is gated on. If the voltage across the
IGBT is greater than a set threshold, the IGBT is gated
off and a shutdown pulse is sent to the VSD Logic Board
shutting down the entire VSD system. A gate driver fault
can be initiated when the VSD is not running.
VSD – Phase B Gate Driver
See Phase A Gate Driver message above.
VSD – Phase C Gate Driver
See Phase A Gate Driver message above.
VSD – Single Phase Input Power
This shutdown is generated by the SCR trigger control
and relayed to the VSD Logic Board to initiate a sys-
tem shutdown. The SCR Trigger control uses circuitry
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