USER’S MANUAL

11.4.2 Process Protection [420]
Submenu with settings regarding protection functions
for the VSD and the motor.
Low Voltage Override [421]
If a dip in the mains supply occurs and the low voltage
override function is enabled, the VSD will automatically
decrease the motor speed to keep control of the
application and prevent an under voltage trip until the
input voltage rises again. Therefore the rotating energy
in the motor/load is used to keep the DC link voltage
level at the override level, for as long as possible or
until the motor comes to a standstill. This is dependent
on the inertia of the motor/load combination and
the load of the motor at the time the dip occurs, see
Fig. 79.
Default: On
Off 0 At a voltage dip the low voltage trip will protect.
On 1
At mains dip, VSD ramps down until voltage
rises.
Communication information
421 Low Volt OR
Stp A
On
Modbus Instance no/DeviceNet no: 43361
Profibus slot/index 170/10
Fieldbus format
UInt
Modbus format
UInt
DC link voltage
Override
level
Low Volt.
level
Rotor locked [422]
With the rotor locked function enabled, the VSD will
protect the motor and application when this is stalled
whilst increasing the motor speed from standstill. This
protection will coast the motor to stop and indicate a
fault when the Torque Limit has been active at very low
speed for more than 5 seconds.
Default: Off
Off 0 No detection
On 1
Communication information
Motor lost [423]
With the motor lost function enabled, the VSD is able
to detect a fault in the motor circuit: motor, motor
cable, thermal relay or output filter. Motor lost will
cause a trip, and the motor will coast to standstill,
when a missing motor phase is detected during a
period of 5 s.
Communication information
VSD will trip when locked rotor is detected.
Trip message “Locked Rotor”.
Modbus Instance no/DeviceNet no: 43362
Profibus slot/index 170/11
Fieldbus format
UInt
Modbus format
UInt
Default:
Off 0
Trip 1
422 Rotor locked
Stp A
Off
423 Motor lost
Stp A
Off
Off
Function switched off to be used if no
motor or very small motor connected.
VSD will trip when the motor is disconnected.
Trip message “Motor Lost”.
Speed
t
Modbus Instance no/DeviceNet no: 43363
Profibus slot/index 170/12
Fieldbus format
UInt
Modbus format
UInt
(06-F60new)
Fig. 79 Low voltage override
t
NOTE: During the low voltage override the LED trip/limit
blinks.
Omron SX inverter manual Functional Description 113