FORM 160.54-O1
153
JOHNSON CONTROLS
2
COMPRESSOR MOTOR VARIABLE
SPEED DRIVE:
CYCLING SHUTDOWN MESSAGES
The following Cycling shutdown messages are displayed
on Compressor Motor Variable Speed Drive (VSD) ap-
plications only. These messages are generated by events
that occur within the VSD. The chiller will automatically
restart when the cycling condition clears. Service and
troubleshooting information is contained in YORK
Manual 160.00-M1.
“VSD SHUTDOWN – REQUESTING
FAULT DATA”
The VSD has shutdown the chiller and the Control
Center has not yet received the cause of the fault from
the VSD, via the serial communications link. The VSD
shuts down the chiller by opening the Motor Controller
VSD Stop Contacts (located on the VSD Logic Board
and connected between TB6-16 and TB6-53 in the
Control Center). The Microboard in the Control Center
then sends a request for the cause of the fault to the
VSD Logic Board via the Adaptive Capacity Control
Board, over the serial link. Since serial communications
are initiated every 2 seconds, this message is typically
displayed for a few seconds and then replaced with one
of the below listed fault messages.
“VSD – STOP CONTACTS OPEN”
Refer to “VSD Shutdown – Requesting Fault Data”
message above. If the Control Center’s Microboard does
not receive the cause of the Fault over the Serial Link
within 20 seconds, it is assumed it is not forthcoming
and that message is replaced with "VSD – STOP CON-
TACTS OPEN" message.
“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 ac-
complished 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.
Refer to VSD – Serial Communications fault. If
communications between the VSD Logic Board,
Harmonic Filter Logic Board, ACC Board and Con-
trol Center Microboard does not take place during
initialization, this message will be generated. The
Serial communications can be veried 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 lter 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 = 771 Amps
503/419 HP = 1200 Amps
790/658 HP = 1890 Amps
If an overcurrent 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 specied 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
Prerotation Vanes cannot close quickly enough to correct
for this sudden increase in current, and the chiller will
trip on an overcurrent fault.
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