Cycling shutdowns
General information
The Shutdowns are organized in alphabetical order based on the OptiView Control Center Panel
messages. The Microcomputer Control Panel messages are also included under these headings.
Whenever the OSCD or Harmonic Filter Logic Board generates a Cycling Shutdown, a series of
events occurs.
•
If the chiller is not running at the time of the shutdown, the OSCD Logic Board does not turn
on the output transistors.
•
The K1 relay on the OSCD logic board de-energizes. This action indicates to the Control
Center that the OSCD has shut down. The K1 relay remains de-energized until the cause of
the shutdown is corrected.
•
If the chiller is running at the time of the shutdown, the Control Center starts a coastdown
period (150 seconds for centrifugal chillers).
•
The message “VSD Shutdown - Requesting Fault Data” is displayed when the Control Center
requests the fault data from the OSCD.
•
The OSCD or Harmonic Filter Logic Board sends a shutdown code to the Control Center. The
microboard interprets the shutdown code, and displays a shutdown message on the display
of the Control Center.
After the coastdown period times out, the chiller automatically restarts if the shutdown is no longer
active. Leave the Compressor Switch in the Run position. The chiller starts if no faults are active.
Cycling shutdown messages
Table 4: Cycling shutdown message
Message
Description
VSD - DC Bus Voltage Imbalance
BUS VOLTAGE IMBALANCE FAULT
The DC link is filtered by many large capacitors, which are rated for 450 VDC.
These capacitors are connected in series to achieve a 900 VDC capability for the
DC link. It is important that the voltage is shared equally between the two sets of
series capacitors. Each set of capacitors must share approximately 1/2 of the total
DC link voltage. If the difference in the voltage between the two sets of capacitors
is greater than ± 88 VDC then this shutdown will occur.
VSD - High DC Bus Voltage
BUS OVER-VOLTAGE FAULT
The DC bus voltage is continuously monitored and a shutdown will occur if the DC
bus voltage exceeds 745 VDC (for 400 VAC and 460 VAC units) or 909 VDC (for 575
VAC units). This shutdown will protect the capacitors from a voltage that exceeds
their rating.
VSD - High Internal Ambient
Temperature
HIGH AMBIENT TEMPERATURE FLT
The ambient temperature of the OSCD is monitored by a temperature sensor
mounted on the OSCD logic board. The high ambient trip threshold is 145°F (63°C)
for all models. If this fault occurs, the fans and coolant pump will remain on until
the internal ambient temperature has fallen to 137°F (58°C).
37
Liquid-Cooled OptiSpeed Compressor Speed Drive
