JOHNSON CONTROLS
227
SECTION 8 - MICROPANEL
FORM 201.23-NM2
ISSUE DATE: 09/25/2020
8
On 4 compressor chillers, the baseplate temperatures
on compressors 1 and 3 are OR’d together and the
highest of the two temperatures is compared in soft-
ware to a limit of 218°F. The baseplate temperatures on
compressors 2 and 4 are OR’d together and the highest
of the two temperatures compared in software to a limit
of 218°F. If the limit is exceeded by either of the 2 in-
puts, the unit will fault and shut down with a controlled
ramped shutdown.
This is an auto-restart safety that will lock out on the
3rd fault in 90 minutes. The fault will be a system fault
for all units. Below are the Status display fault mes-
sages for all systems.
SYS X YYYYYYYY HIGH VSD BASEPLATE TEMP
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 un-
til the operator clears the fault using the keypad.
After a fault, the fan(s) and water pump will remain
energized until the inverter power module base plate
temperature(s) falls below 165°F.
The system will be allowed to restart when the inverter
power module base plate temperatures drop below this
value.
It is possible for an internal sensor to fail and not sense
temperature without causing a high baseplate sensor
fault.
High VSD Internal Ambient Temperature
(Software) Fault
The VSD Logic board contains a temperature sensor,
which monitors the unit’s internal ambient tempera-
ture. If the VSD internal ambient temperature rises
above the cutout of 158°F, the unit will fault and shut
down with a controlled ramped shutdown.
This safety will not cause a lockout. The fault will be a
unit fault for all units. Following is the Status display
fault message.
UNIT YYYYYYYY
HIGH VSD INTERNAL AMBIENT TEMP
The unit will be allowed to restart when the internal
ambient temperature drops 10°F below the cutout.
YYYYYYYY indicates the unit is in a "Fault" condi-
tion and will restart when the condition clears.
Single Phase Input (Hardware) Fault
The VSD’s SCR Trigger Control board contains cir-
cuitry that checks the three phase mains for the pres-
ence of all three-line voltages. If any of the line volt-
ages are not present, the system will immediately shut
down on a fault.
This fault will not cause a lockout. The fault will be
a unit fault for 2 or 3 compressor units. Below is the
Status display fault message.
UNIT YYYYYYYY
SINGLE PHASE INPUT VOLTAGE
The fault will be a system fault 1/3 or 2/4 for 4 com-
pressor units. Two key presses of the STATUS key are
required to show the fault on both systems. Below is
the fault message for all systems.
SYS X YYYYYYYY SINGLE PHASE INPUT VOLTS
X indicates the system and YYYYYYY indicates the
system is “FAULT” and will restart when the single
phase condition clears.
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.
UNIT YYYYYYYY
VSD LOGIC BOARD POWER SUPPLY
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 com-
mands (hardware and software) a 5 second timer will
commence timing. The hardware run signal comes
from the SYS X VSD Run Signal to the VSD Log-
ic Board. The software run signal comes through the
comms from the Chiller Control Board. If the missing
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