ABB ACSM1 Firmware Manual page 23

If there is an emergency stop circuit in use, check that the circuit
functions (emergency stop signal is connected to the digital input
which is selected as the source for the emergency stop activation).
The Safe Torque Off function disables the control voltage of the power semiconductors of the drive
output stage, thus preventing the inverter from generating the voltage required to rotate the motor.
For Safe Torque Off wiring, see the appropriate hardware manual.
If there is a Safe Torque Off circuit in use, check that the circuit
functions.
Selects how the drive reacts when the Safe Torque Off function is
active (i.e. when the control voltage of the power semiconductors of
the drive output stage is disabled).
If the DC voltage drops due to input power cut off, the undervoltage controller will automatically
decrease the motor torque in order to keep the voltage above the lower limit.
To prevent the DC voltage from exceeding the overvoltage control limit, the overvoltage controller
automatically decreases the generating torque when the limit is reached.
When the overvoltage controller is limiting the generating torque, quick deceleration of the motor is
not possible. Thus electrical braking (brake chopper and brake resistor) is needed in some
applications to allow the drive to dissipate regenerative energy. The chopper connects the brake
resistor to the intermediate circuit of the drive whenever the DC voltage exceeds the maximum limit.
Check that the overvoltage and undervoltage controllers are active.
If the application requires a brake resistor (the drive has a built-in
brake chopper):
• Set the brake chopper and resistor settings.
Note: When a brake chopper and resistor are used, the overvoltage
controller must be deactivated by parameter
CTRL.
• Check that the connection functions.
For more information on the brake resistor connection, see the
appropriate hardware manual.
Emergency stop circuit
Safe Torque Off
Voltage control
47.01 OVERVOLTAGE
23
10.10 EM STOP OFF3 or
10.11 EM STOP OFF1
(emergency stop control
through fieldbus 2.12
FBA MAIN CW bits 2...4)
46.07 STO DIAGNOSTIC
47.01 OVERVOLTAGE
CTRL
47.02 UNDERVOLT
CTRL
48.01...48.07
47.01 OVERVOLTAGE
CTRL
Start-up