User Manual V 1-4.XX User guide

Troubleshooting 12-17
You can use bits 0 – 4 of Bus/Brake Opts to control the slew rate of
the bus voltage tracker. Refer to the section on the bus voltage tracker
later in this chapter for additional information.
Understanding Ridethrough
Ridethrough provides current inrush protection and extended logic
operating time if the power lines drop out while the drive is running.
The drive is immediately disabled when it senses that the incoming
power lines dropped out (bus capacitor voltage drop). The energy
stored in the bus capacitors keeps the logic supplies running for an
extended time. If the power lines return before the logic power
supplies lose power, you can configure the drive to resume operation
without system intervention (default). The ridethrough timeout is set
for two seconds. This means that the drive is configured to fault
(default setting) and not auto-restart if the dropout lasts more than two
seconds.
Fault Select 1 (parameter 20) and Warning Select 1 (parameter 21) let
you specify how you want the drive to report specific precharge and
ridethrough information.
Ridethrough also protects the drive from excessive inrush current
when the power returns by entering a precharge mode when
ridethrough is initiated. After precharge has finished, the drive can
complete ridethrough and resume normal drive operation. The drive is
enabled again after the bus rises to within 75 volts of the bus voltage
tracker value.
Use the following parameters to configure the precharge and
ridethrough functions:
• Fault Select 1 (parameter 20)
• Warning Select 1 (parameter 21)
• Bus/Brake Opts (parameter 13)
• Line Undervolts (parameter 27)
In addition, Test Select 1 (parameter 93) and Test Data 1
(parameter 92) contain software testpoints that provide additional
precharge information.
!
ATTENTION: You must determine safe auto-restart
and fault configurations at the system and user level.
Incorrect selection(s) may result in safety concerns
and/or drive damage.
file:
Fault Setup
group:
Fault Config
!
ATTENTION: If you are using an external logic power
supply, the drive may be able to stay in an indefinite
ridethrough state. If the power returns to the drive (much
later), the drive automatically restarts. You must
therefore handle the control of enable, faults, time-outs,
drive configuration, and safety issues at the system level.