205
JOHNSON CONTROLS
FORM 201.21-NM4 (1020)
205
JOHNSON CONTROLS
8
VSD SAFETIES (FAULTS) (CON'T)
POWER SUPPLY (HARDWARE) FAULT
Various DC power supplies which power the VSD Logic
Board are monitored via hardware located on the logic
board. If any of these power supplies fall outside their
allowable limits, the unit will immediately shut down
on a fault.
This is an auto-restart safety that will restart after the
fault clears and lock out on the 3rd fault in 90 minutes.
The fault will be a unit fault for all units. Below is the
Status display fault message.
YYYYYYY indicates the system is in a “FAULT” con-
dition and will restart when the fault clears or “LOCK-
OUT” and will not restart until the operator clears the
fault using the keypad.
Run Relay (Software) Fault
Upon receipt of either of the two types of run commands
(hardware and software) a 5 second timer will com-
mence timing. The hardware run signal comes from the
SYS X VSD Run Signal to the VSD Logic Board. The
software run signal comes through the comms from the
Chiller Control Board. If the missing run signal is not
asserted within the 5-second window, the system will
fault. In addition, if either run signal is disabled while
the VSD is running, the remaining run signal must be
disabled within 5 seconds after the VSD is shut down or
the system will fault. If running, the unit will fault and
shut down with a controlled ramped shutdown.
Control Panel Info: This is an auto-restart safety that will
autostart after the 120 second anti-recycle timer times
out and will lock out on the 3rd fault in 90 minutes. The
fault is combined as a 1/3 or 2/4 system fault. Below
are the fault messages for all systems.
UNIT YYYYYYYY
VSD LOGIC BOARD POWER SUPPLY
X indicates the system and YYYYYYY indicates the
system is in a “FAULT” condition and will restart when
the fault clears or “LOCKOUT” and will not restart until
the operator clears the fault using the keypad.
SYS X YYYYYYYY VSD RUN RELAY
VSD Logic Board Failure (Software) Fault
Upon receipt of the voltage and frequency commands,
the PWM generator will acknowledge receipt of the
command. If the system microprocessor does not re-
ceive the handshake within 1.5 seconds of issuing the
command, the unit will trip. This safety is only active
during precharge and during running of a compressor.
It is not active when all the compressors are shut down
and the precharge is disabled. If the VSD Logic Board
Fault occurs while the chiller is running, all systems will
immediately shut down on a fault.
This is an auto-restart safety that will auto restart after
the 120 second anti-recycle timer times out and lock out
on the 3rd fault in 90 minutes. The fault is a unit fault
for all units. Following is the fault message.
VSD CT Plug (Hardware) Fault
Jumpers are installed in each CT plug on the VSD Logic
Board to feed back signals to indicate if the plugs are
installed or not. If either plug is not installed, a low value
is read on the digital input and the unit will immediate
shutdown on a fault or will not run if off.
This is an auto-restart safety that will restart after the
120 second anti-recycle timer times out and lock out on
the 3rd fault in 90 minutes. The fault is a unit fault for
all units. Following is the fault message.
YYYYYYYY indicates the system is in a "FAULT"
condition and will restart or "LOCKOUT" and will
not restart until the operator clears the fault using the
keypad.
UNIT YYYYYYYY
VSD LOGIC BOARD FAILURE
UNIT YYYYYYYY
VSD CT PLUG FAULT
