SECTION 3 - DISPLAY MESSAGES
JOHNSON CONTROLS
187
FORM 160.54-O1
ISSUE DATE: 9/10/2014
3
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:
•
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 cor-
rect 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.
With software version C.OPT.01.23.307 (and later), 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
to detect the loss of any one of the three input phases.
The Trigger will detect the loss of a phase within one
half line cycle of the phase loss. This message is also
displayed every time power to the VSD is removed or
if the input power dips to a very low level.
VSD – High DC Bus Voltage
The VSD’s DC Link Voltage is continuously moni-
tored and if the level exceeds 745VDC, a Bus Over-
Voltage shutdown is initiated. If this shutdown occurs,
it will be necessary to look at the level of the 460VAC
applied to the drive. The specified voltage range is 414
to 508VAC. If the incoming voltage is in excess of
508VAC, steps should be taken to reduce the voltage to
within the specified limits.
VSD – Logic Board Power Supply
This shutdown is generated by the VSD Logic Board
and it indicates that the low voltage power supplies
for the Logic Boards have dropped below their allow-
able operating limits. The power supplies for the Logic
Boards are derived from the secondary of the 120 to
24VAC transformer, which in turn, is derived from the
480 to 120VAC control power transformer. This mes-
sage usually means the power to the VSD has been re-
moved.
VSD – Low DC Bus Voltage
If the DC link drops below 500VDC (or 414VDC for
50Hz applications), the drive will initiate a system
shutdown. A common cause for this shutdown is a se-
vere sag in the incoming power to the drive. Monitor
the incoming three-phase AC line for severe sags and
also monitor the DC link with a voltmeter.
