JOHNSON CONTROLS
124
FORM 160.78-O2
ISSUE DATE: 5/22/2017
SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION
MESSAGE DESCRIPTION
VSD – PRECHARGE – LOW DC
BUS VOLTAGE 1
During Pre-charge, the dc-link voltage must reach at least low threshold which is
determined by Line Voltage Setpoint (see the table below) within 4 seconds after the
pre-charge signal has been commanded. If this condition is not met, this shutdown is
generated. The VSD logic board shall time 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 LOW THRESHOLD (VOLTS)
460 50
380/415 41
230 25
VSD – PRECHARGE – LOW DC
BUS VOLTAGE 2
During Pre-charge, the dc-link voltage must reach at least high threshold which is
determined by Line Voltage Setpoint (see the table below) within 15 seconds after the
pre-charge signal has been commanded. If this condition is not met, this shutdown is
generated. The VSD logic board shall time 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 LOW THRESHOLD (VOLTS)
460 500
380/415 414
230 250
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 com-
mands by the VSD, a 5 second timer shall commence timing. If both run commands are
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
COMMUNICATIONS
This message is generated by OptiView when communications between the control
center Microboard and the VSD Logic Board, causes no response over 3 attempts
consecutively. This is generally indicative of defective wiring between 2TB on the VSD
Logic Board and the Microboard J13.
VSD – SERIAL RECEIVE
The VSD logic board does not receive valid communication from the control panel for
10 consecutive seconds.
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 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 rms value of each of the three line-to-line voltages on a cycle-by-
cycle basis If the rms value of any one of the three line-to-line voltages falls below 200
Vrms in any one cycle, this shutdown is generated.
VSD – STOP (FAULT)
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 CONTACTS OPEN” message.
TABLE 8 - CYCLING SHUTDOWN MESSAGES (CONT'D)
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