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MICRO PANEL
VSD Fault Data
When a fault has occurred, the VSD Logic Board will
capture fault data. This data will be stored in the on-
board battery backed RAM for safekeeping and trans-
ferred to the panel via the communications link as soon
as possible.
A fault code will be set for the fault that initiated the
system shutdown. This fault will appear as a specific
fault in the Status message.
Any faults that occur after the initial fault, which occur
within the comms transmission time frame following the
inception of the first fault, will be stored and transmitted
to the Micro Logic Board together with the first fault
data. These faults will appear in the "All Fault" display
in the History.
A snapshot of the operating parameters of the VSD is
continuously updated in battery-backed memory once
every program loop. Upon receipt of a first fault, the
snapshot of the operating parameters will be stored in
memory and are transmitted to the panel as the fault
data.
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VSD SAFETIES (FAULTS) (CON'T)
Fault Relay/Fault Acknowledge Bit
Control of the Fault Relay is from the VSD Logic Board.
The Fault Relay on the VSD will be closed during a
non-fault condition.
When a running or pre-charge fault occurs on the VSD,
the fault relay will immediately open. The relay will
not open for non-running faults that occur.
When the Chiller Control Board sees the VSD fault relay
open, it will immediately take a snapshot of system data
and save it to the history buffer.
A fault acknowledge bit from the Chiller Control Board
is sent to the VSD via comms after receiving valid fault
data from the VSD. When the VSD Logic Board re-
ceives the fault acknowledge via comms from the panel
it will reset (close) the Fault Relay. The fault acknowl-
edge is reset by the Chiller Control Board after the Fault
Relay is closed by the VSD Logic Board.
VSD Fault Compressor Start Inhibit
If a VSD fault condition exists while the compressor is
not running or pre-charging, the Chiller Control Board
will not try to start the faulted compressor(s). The start
inhibit will be automatically cleared when the fault
condition goes away.
FORM 201.21-NM1 (1223)
JOHNSON CONTROLS
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