FORM 160.77-O2
ISSUE DATE: 11/15/2011
JOHNSON CONTROLS
124
SECTION 5 - DISPLAY MESSAGES
Pri VSD Fault: Precharge Low DC Bus Voltage
The System Control Center 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 voltages are monitored,
and when the when the minimum value of all DC Link
voltages reaches a level of 1238V (75% of 1650 VDC)
the bypass contactor closes.
During the pre-charge interval all DC bus voltages will
be compared to a voltage threshold level of 330VDC
(20% of 1650VDC) 0.5 seconds after initiation of pre-
charge. If all DC bus voltages do not meet or exceed
the 330VDC threshold, the unit will prohibit a system
start, initiate a cycling shutdown and the control panel
will display the message “PRI VSD FAULT: PRE-
CHARGE LOW DC BUS VOLTAGE”.
Pri VSD Fault: High Output Frequency
The fundamental frequency of the drives output volt-
age is measured by monitoring the fundamental fre-
quency of the control signals being sent to the gate
driver controls. The fundamental frequency detected
will be compared to a threshold of 65 Hz for 60 Hz
units and 55 Hz for 50 Hz units. If the frequency limit
threshold is exceeded, the unit initiates a safety shut-
down and the control panel will display the message
“PRI VSD FAULT: HIGH OUTPUT FREQUENCY”.
Pri VSD Fault: Single Phase Input Power
The drive monitors each of the three phase line-to-line
voltages to the drives input terminals on a cycle-by-cy-
cle basis. If the RMS voltage of any of the three inputs
drops below 75% of the drives nameplate voltage rat-
ing, the unit initiates a shutdown and the control panel
displays the message “PRI VSD FAULT: SINGLE
PHASE INPUT POWER”.
Pri VSD Fault: Contactor Fault
Auxiliary contacts are supplied to both the input contactor
and the input disconnect switch. If the auxiliary contact
for the input contactor is not in the proper state (Pre-
charge Contactor Open Fault), or if the auxiliary contact
for the input disconnect switch is not in the proper state
(Input Contactor Open Fault) the drive initiates a safety
shutdown and the system control panel displays the mes-
sage “PRI VSD FAULT: CONTACTOR FAULT”.
Pri VSD Fault: Loss of Cooling Fan
The unit contains dedicated fan motor thermal over-
loads for each of the cooling fan motors used within
the drive. The drive also contains a voltage sensitive
relay applied to the cooling fans power source. This
relay contains a normally open contact, which closes
when the fan voltage is above a minimum threshold
(60% of nominal). The cooling fan’s motor starter also
includes an auxiliary contact that opens when the start-
er is in the manual “off” position.
The motor starter also includes thermal overload pro-
tection that must be manually reset, and opens the mo-
tor starter auxiliary contact when tripped. If any one of
the fan motor thermal overloads trip, the voltage sup-
plied to the fans is below the minimum threshold or
the manual fan motor starter is in the “off” mode or its
thermal overload is tripped, the unit initiates a cycling
shutdown and the control panel displays the message
“PRI VSD FAULT: LOSS OF COOLING FAN”.
The unit remains tripped while the motor starter over-
loads are tripped, the starter is in the manual “off” posi-
tion, or the motor thermal overloads are tripped. The
unit automatically resets following motor cool down, if
tripped by the motors internal thermal protection, per-
mitting the system to automatically restart.
Pri VSD Fault: 105% Motor Overload Current
The overload threshold and timer functions reside in
the drive. A comparator will compare the average of
the three phase currents against 1.05 times the 100%
Job FLA limit. If the average of the three phase cur-
rents exceeds the limit continuously for forty seconds,
the unit initiates a safety shutdown and the control pan-
el displays the message “PRI VSD FAULT: 105% MO-
TOR OVERLOAD CURRENT”. In order to initiate
restart, the control panel’s reset button must be pressed.
Pri VSD Fault: Low DC Bus Voltage
All DC bus voltages will be continuously monitored
and if any one of the voltages drops below a threshold
level of 1238VDC (75% of 1650VDC) continuously
for a time period of 30 milliseconds, the unit will initi-
ate a cycling shutdown and the control panel will dis-
play the message “PRI VSD FAULT: LOW DC BUS
VOLTAGE”.
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