Specifications

56
JOHNSON CONTROLS
Form 201.28-NM1.EN.PED/CE (0211)
OPERATION
Motor Current Overload (Software) Fault
The Motor Current Overload will compare the highest
of the 3 phases of motor current per compressor to
the compressor’s 105 % FLA ADJUST (overload)
potentiometer setting on the VSD Logic Board. If the
current exceeds the setting continuously for 20 seconds,
the compressor will trip.
This safety will lock out a system on the 1st fault and
shut down with a controlled ramped shutdown. The fault
will be an individual system/compressor fault. A sample
Status display fault is shown below:
SYS X FAULT: MOTOR CURRENT OVERLOAD
X indicates the system and FAULT 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.
Motor Current Overload (Hardware) Fault
The Motor Current Overload will compare the highest
of the 3 phases of motor current per compressor to the
compressor’s overload ADJUST potentiometer setting.
If the current exceeds the setting continuously for 30
seconds, all compressors will fault and shut down
immediately.
The fault will be a unit fault and will lock out all systems
on the first fault. A sample Status display fault is shown
below:
UNIT FAULT:
MOTOR CURRENT OVERLOAD
FAULT indicates the unit is in a "Lockout" condition and
will not restart until the operator clears the fault using
the keypad.
IGBT Gate Driver (Hardware) Fault
The unit’s phase bank assembly(s) contains one IGBT
gate driver control board per compressor. These boards
monitor the saturation voltage drop across each of the six
IGBT’s while gated on. If the IGBT’s saturation voltage
exceeds the prescribed limit, the gate driver will make
the determination that a short circuit is present. This in
turn will cause the system to trip.
During normal operation, the voltage drop across a
saturated IGBT is low. When a short or shoot occurs,
the extremely high current causes the voltage across the
device to increase. When the electronic hardware on
the IGBT Gate Driver Board senses the current rise, it
immediately turns off all IGBT’s in the module and the
system will shut down immediately.
Additionally, if the IGBT’s Gate Driver board’s power
supply voltage falls below the permissible limit, this
same fault will be generated.
This is an auto-restart safety that will lock out on the
3rd fault in 90 minutes. The fault will be a system fault.
Following is the Status display fault messages for all
systems.
SYS X FAULT: GATE DRIVER
X indicates the system and FAULT 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.
High Baseplate Temperature (Software) Fault
Each phase bank assembly contains one liquid cooled
heatsink to cool both the inverter power modules and
the converter SCR/Diode modules. Each compressor’s
inverter power module (6 IGBT’s & Gate Driver Board)
contains an internal temperature sensor (5K ohm at
25°C) to monitor the baseplate temperature.
The outputs from System 1 and System 2 sensors are
each compared in software to a limit of 107.8°C (226°F).
If either sensor exceeds this limit, 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. Below are the Status display fault messages for
all systems.
SYS X FAULT: HIGH VSD BASEPLATE TEMP
X indicates the system and FAULT 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.
After a fault, the fan(s) and water pump will remain
energized until the inverter power module base plate
temperature(s) falls below 73.9°C (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.