York YT Millennium, Operating & Maintenance, Page: 101 / 156

FORM 160.55-O1 (920)
101
YORK INTERNATIONAL
“ VSD SHUTDOWN – REQUESTING
FAULT DATA ”
The VSD has shut down the chiller and the OptiView
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 OptiView Control Center). The Microboard
in the OptiView 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 OptiView 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 CONTACTS 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 OptiView 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 dis-
connect 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 verified by selecting
the VSD DETAILS screen from the MOTOR screen
and observing the Full Load amps value. A zero dis-
played 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 re-
moving 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 instan-
taneous 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 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
Prerotation Vanes cannot close quickly enough to correct
for this sudden increase in current and the chiller will
trip on an overcurrent 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.
“ VSD – HIGH PHASE B
INSTANTANEOUS CURRENT ”
See “ High Phase A Instantaneous Current ” message
above.
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