JOHNSON CONTROLS
17
SECTION 2 - SAFETY SHUTDOWNS
FORM 160.00-O10
ISSUE DATE: 8/24/2020
2
MESSAGE
DESCRIPTION
VSD – 105% MOTOR
CURRENT OVERLOAD
The 105% motor current overload value is based on the highest output current compared
to the programmed Motor Current value displayed on the Control panel. The 105% motor
current over-load value is 1.05 times the programmed Motor Current value displayed on
the Control panel.
The motor current overload value must be greater than the shutdown value for 40
continuous seconds for this shutdown to occur.
DRIVE MODEL
MAXIMUM MOTOR CURRENT OVERLOAD
SHUTDOWN VALUE
1100
1024 Amps
1300
1209 Amps
VSD – MOTOR CURRENT THD
FAULT
This shutdown provides protection to the compressor motor. High levels of current total
harmonic distortion (THD) can cause the motor to overheat. Verify that all wiring is
properly connected between the inverter and the output harmonic filter.
VSD – PHASE A INPUT DCCT
The input current in each phase to the VSD is measured during the precharge time. If
the input current does not exceed the shutdown value for the given model of drive listed
below, then this shutdown is generated.
DRIVE MODEL MINIMUM INPUT CURRENT SHUTDOWN VALUE
1100/1300
5.0 Amps
VSD – PHASE B INPUT DCCT
See “VSD –PHASE A INPUT DCCT” message preceding.
VSD – PHASE C INPUT DCCT
See “VSD –PHASE A INPUT DCCT” message preceding.
VSD – PHASE A MOTOR
DCCT
The motor current in each phase of the VSD is measured at the beginning of the run
command. The motor current at this time should measure very low. This low value will
be used as the zero current value for the rest of this run time. The motor current is then
monitored for the next 1.5 seconds to ensure that a minimum amount of current is flowing
to the motor. If at the end of the 1.5 second time a minimum of 25 amps peak is not
detected, then this shutdown is generated.
VSD – PHASE B MOTOR
DCCT
See “VSD –PHASE A MOTOR DCCT” message preceding.
VSD – PHASE C MOTOR
DCCT
See “VSD –PHASE A MOTOR DCCT” message preceding.
VSD – PHASE LOCKED LOOP
The VSD must be able to determine the input voltage frequency from the input voltage
measurement. If the input voltage frequency is not stable enough for the VSD to make
this determination, then this shutdown is generated.
VSD – PRECHARGE
LOCKOUT
If the unit fails to complete pre-charge (due to VSD – PRECHARGE – LOW DC BUS
VOLTAGE or VSD – PRECHARGE – HIGH DC BUS VOLTAGE), the VSD shall time 10
seconds before clearing the fault and allowing another pre-charge to start. The unit’s
fan(s) and water pump(s) shall remain energized during this time. The VSD shall allow up
to three consecutive pre-charge- related faults to occur. After the third consecutive pre-
charge-related fault, this shutdown is generated.
VSD – RECTIFIER PROGRAM
FAULT
The VSD software contains a verification process to ensure that the correct set of
software is installed in the VSD logic board for the application.
VSD SHUTDOWN –
REQUESTING FAULT DATA
The VSD has shut down the chiller and the control center has not yet received the cause
of the fault from the VSD, via the serial communications link. The VSD shuts down the
chiller by opening the Motor Controller “VSD Stop Contacts” (located on the VSD Logic
Board and connected between TB6-16 and TB6-53 in the control center). The Microboard
in the control center then sends a request for the cause of the fault to the VSD Logic
Board over the serial link. Since serial communications are initiated every 2 seconds, this
message is typically displayed for a few seconds and then replaced with one of the other
VSD fault messages.
TABLE 2 -
SAFETY SHUTDOWNS MESSAGE (CONT'D)
