FORM 160.77-O2
ISSUE DATE: 11/15/2011
JOHNSON CONTROLS
122
SECTION 5 - DISPLAY MESSAGES
PRIMARY VARIABLE SPEED DRIVE
FAULT MESSAGES
The following cycling shutdown messages are dis-
played on compressor motor Medium Voltage Variable
Speed Drive (MV VSD) applications only.
Pri VSD Fault: Precharge DC BUS Voltage
Imbalance XY
The System Control panel will provide a pre-charge
signal to the drive via the serial communications link.
Following receipt of the pre-charge command the
drive will enter the pre-charge interval. During the pre-
charge interval the input Main Vacuum contactor will
close and the pre-charge contactor, which shunts an in-
put inductor, will remain open.
During the pre-charge interval, all of the DC Link volt-
ages are monitored, and when the minimum value of
all DC Link voltages reaches a level of 1238 V (75%
of 1650 VDC) the pre-charge contactor closes. During
the pre-charge interval the absolute value of the differ-
ence between the positive and negative bus voltages on
all phases must remain within a range of 0 VDC to 248
VDC (15% of 1650VDC). If the absolute value of this
difference exceeds the range continuously for a time
period of 3 milliseconds, the unit will prohibit a sys-
tem start, initiate a shutdown and the control panel dis-
plays the message “PRI VSD FAULT: PRECHARGE
DC BUS VOLTAGE IMBALANCE XY”, where X
denotes the Power pole phase location (A, B or C) and
Y denotes the location of the cell within that phase (U,
upper or L, lower).
Pri VSD Fault: DC BUS Voltage Imbalance XY
The absolute value of the difference between the posi-
tive and negative bus voltages on all phases will re-
main within a range of 413VDC (25% of 1650VDC). If
the absolute value of this difference exceeds the range
continuously for a time period of 3 milliseconds, the
unit initiates a cycling shutdown and the control panel
will display the message “PRI VSD FAULT: DC BUS
VOLTAGE IMBALANCE XY”, where X denotes the
Power cell phase location (A, B or C) and Y denotes
the location of the cell within that phase (U, upper or
L, lower).
Pri VSD Fault: Power Transformer High Temp
The input power transformer will be supplied with
three temperature sensor Klixons® wired in series, set
to trip at 200°F (Hammond as transformer manufac-
turer) or 190°F (Hitran as transformer manufacturer).
If any one of the three input power transformer Klix-
ons® open, the unit initiates a safety shutdown and the
control panel displays the message “PRI VSD FAULT:
POWER TRANSFORMER HIGH TEMP”. In order to
initiate restart, the control panel’s reset button must be
pressed.
Pri VSD Fault: Initialization Failed
The MV VSD will initiate a shutdown of the system
under the following conditions:
• After power has been applied to the system the
control panel will attempt to establish communi-
cations with the MV VSD using the 3-wire plus
shield communications link. The control panel
will attempt to establish communications with the
MV VSD ten times during initialization. If estab-
lishment of the communications link is unsuccess-
ful, the control panel will prohibit a system start,
initiate a cycling shutdown and the control panel
will display the message “PRI VSD FAULT: INI-
TIALIZATION FAILED”.
• During initialization the MV VSD will transmit
Hp and Voltage codes to the Control Panel. These
codes will provide the Control Panel with the Hp
and Input Voltage ratings for display purposes. If
valid Hp and Voltage codes are not received upon
initialization, the unit will prohibit a system start,
initiate a shutdown, and the control panel will dis-
play the message “PRI VSD FAULT: INITIAL-
IZATION FAILED”.
• In addition, upon receipt of a Run signal from the
control panel, the drive will perform an operation-
al check of the DC current transformers monitor-
ing the current ow in the conductors attached to
output terminals A and C.
• If the drive determines that the transformers are
not operational, the unit will prohibit a system
start, initiate a cycling shutdown and the control
panel will display the message “PRI VSD FAULT:
INITIALIZATION FAILED”.
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