JOHNSON CONTROLS
22
FORM 160.00-O10
ISSUE DATE: 8/24/2020
SECTION 3 - CYCLING SHUTDOWNS
MESSAGE
DESCRIPTION
VSD – PRECHARGE – LOW
DC BUS VOLTAGE 2
During Pre-charge, the DC bus voltage must exceed the minimum threshold which is
determined by Line Voltage Setpoint (see the table below) within 12 seconds after the
pre-charge signal has been commanded. If this condition is not met, this shutdown is
generated. The VSD logic board shall wait 10 seconds before clearing the fault and
allowing another pre-charge to start. The VFD’s fan(s) and water pump(s) shall remain
energized during this time. The VSD logic board shall allow up to three consecutive pre-
charge-related faults to occur. After the third consecutive pre-charge-related fault, Safety
Shutdown message “VSD – PRECHARGE LOCKOUT” is generated.
LINE VOLTAGE
MINIMUM THRESHOLD (VOLTS)
380/415
414
460
500
VSD – RUN SIGNAL
Redundant RUN signals are generated by the control center; one via TB6-24 and the
second via the Serial Communications link. Upon receipt of either of the two RUN
commands by the VSD, a 5 second timer shall commence timing. If the run signal
on TB6-24 is not received by the VSD Logic Board within 5 seconds, a shutdown is
performed and this message is displayed. This is generally indicative of a wiring problem
between the control center and the VSD.
VSD – SERIAL RECEIVE
This shutdown is generated when the VSD logic board has not received a valid
communications packet from the control center for 10 consecutive seconds.
VSD SHUTDOWN –
REQUESTING FAULT DATA
The VSD has shut down 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. The control center then
sends a request for the cause of the fault to the VSD 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 other VSD fault messages.
VSD – SINGLE PHASE INPUT
POWER
The VSD monitors the input voltage of all three phases. If the input voltage of any one
phase drops below the threshold value for the given input voltage range below, then this
shutdown will occur.
INPUT VOLTAGE
RANGE
INPUT VOLTAGE SINGLE PHASE SHUTDOWN
VALUE (VOLTS)
380/415
264
460
295
VSD - STOP CONTACTS
OPEN
Whenever the OSCD initiates a fault, it first opens the fault relay on the OSCD logic
board. When the relay opens a message is sent to the OptiView panel microboard,
detailing the cause of the fault. If this circuit ever opens without receiving an
accompanying cause for the fault over the communication link within 20 seconds then this
message will be displayed. This fault may be replaced with a Serial Communications fault
if the serial link has failed.
TABLE 3 -
CYCLING SHUTDOWN MESSAGE (CONT'D)