Table 4: Cycling shutdown message
Message
Description
This shutdown is generated by the OSCD logic board. If any one phase of motor
current as measured by the Output Current Transformers exceeds a threshold.
Refer to the chart below for the shutdown threshold value.
Drive hp rating
Threshold shutdown value
270, 292, 351, 424
771 Amps Peak
385, 419, 503, 608
1200 Amps Peak
546, 575, 608 (400 VAC), 658, 704, 750 790 1890 Amps Peak
900, 914, 917, 948, 1055, 1100
2749 Amps Peak
VSD - High Phase A (or B, C)
Instantaneous Current
PHASE A (OR B, C) OVERCURRENT
FAULT
If an Instantaneous Current Fault 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 OSCD that is in excess of the specified dip voltage rating for this product. This
is especially true if the chiller was running at, or near, full load. If there is a sudden
dip in line voltage, the current to the motor will increase. The chiller vanes cannot
close quickly enough to correct for this sudden increase in current and the chiller
will trip on this fault.
VSD - Initialization Failed
VSD INITIALIZATION FAILED
At power-up, the OSCD logic board will go through a process called initialization.
At this time, memory locations are cleared, jumper positions are checked, and
communications links are established between the OSCD logic board, and the
Control Center.
VSD - Invalid Current Scale Selection
INVALID CURRENT SCALE FAULT
The J1 connector on the OSCD logic board contains jumpers along with wires from
the output CTs. The jumpers configure the OSCD logic board to the HP rating of
the OSCD being used in this application in order to properly scale the output cur-
rent. If the jumper configuration is found by the logic board to be invalid, the
system will be shut down and the above message will be generated. The proper
jumper configuration is shown on the wiring label for the OSCD.
VSD - Logic Board Power Supply
MAIN BOARD POWER SUPPLY
This shutdown is generated by the OSCD logic board, and it indicates that one of
the low voltage power supplies for the OSCD logic board has dropped below their
allowable operating limits. The power supplies for the logic boards are derived
from the secondary of the 120 VAC to 24 VAC transformer which in turn is derived
from the 480 VAC to 120 VAC control transformer.
VSD - Logic Board Processor
PWM COMMUNICATIONS FAULT
This shutdown is generated by the OSCD logic board. If a communications
problem occurs between the two microprocessors on the OSCD logic board this
shutdown will occur.
VSD - Low Converter Heatsink
Temperature
LOW CONV HEATSINK TEMP.
A thermistor sensor is located on the SCR/Diode block side of the copper chill
plate on the OSCD Power Unit. Anytime this thermistor detects a temperature of
37°F (3°C) or lower a shutdown will occur.
VSD - Low DC Bus Voltage
LOW DC BUS VOLTAGE FLT
If the line voltage were to quickly drop the current seen by the motor could exceed
it’s rating. The low bus voltage shutdown will prevent this from happening. The
shutdown is generated when the DC link voltage drops below 500 VDC for 460 VAC
input voltage, 414 VDC for 380, 400, and 415 VAC input voltage or 600 VDC for 575
VAC input voltage.
VSD - Low Inverter Baseplate
Temperature
LOW INVERTER BASEPLATE
TEMPERATURE FLT
A thermistor sensor is located inside the transistor module(s) on the OSCD power
unit. Any time this thermistor detects a temperature of 37°F (3°C) or lower a shut-
down will occur. The displayed message will change to LOW INVERTER PHASE (A,
B, or C) when more than one transistor module is used in the power assembly.
VSD - Phase A (or B, C) Gate Driver
PHASE A (B, C) GATE DRIVER FLT
A second level of overcurrent current protection exists on the OSCD gate driver
board. The collector-to-emitter voltage of each transistor module is checked while
the device is turned on. This is called the collector-to-emitter saturation voltage.
If the voltage across the transistor module is greater than a set threshold, the
transistor module is turned off. This fault can also be caused if the transistor is not
being turned on when it should.
VSD - Precharge - DC Bus Voltage
Imbalance
PRECHARGE BUS V IMBALANCE
The definition for this fault is identical to “VSD - DC Bus Voltage Imbalance” except
that the fault has occurred during the precharge period, which begins during pre-
lube. Refer to “ VSD - DC Bus Voltage Imbalance” shutdown for more details.
Liquid-Cooled OptiSpeed Compressor Speed Drive
38
