ABB ACS800 Firmware Manual page 115

115
As seen in the state diagram, the brake Open command is triggered when the drive
comes to the run mode after the motor gets magnetised. The drive waits for the
Torque proving ok signal and then releases the brake Open command, which
switches on the brake open relay output. Any rotation of the motor above the allowed
motor slip speed during the torque generation will result in a brake slip fault. The
drive waits for the period of the brake open delay for the brake to get opened
mechanically. The drive supervises for a brake fault if the brake does not open within
the period of the brake open delay time. If the brake open delay has elapsed, the
drive moves on to the next state for the releasing of the speed reference.
The (42.09) EXTEND RUN T can be used when the start request is released within a
short span on receiving the Stop command. The drive keeps the motor magnetised
for the extended time, and thereby reduces the next start sequence time. In the local
control mode, the extended run time can be stopped by pressing the CDP stop
button twice. The second stop request should be given when the drive is in the
extended time period.
The (42.13) BRK LONG FLT DLY can be used for safety purposes if the brake is not
closed properly in the stopping sequence. The delay is applicable only when
encoder feedback is used and when the brake acknowledge is configured to a DI.
The drive checks for the brake acknowledge signal during the stopping sequence. If
the signal remains ON after the brake close delay (Par. 42.04) has elapsed, the drive
keeps the torque ON to the motor for the brake long fault delay period. This ensures
that the drive does not trip immediately and drops the load. During the brake long
fault delay period, a signal (03.32 bit 9) is activated which can be used for safety
interlocks. If the brake long fault delay has elapsed and the brake acknowledge is
still ON, the drive trips on a brake fault. See the figure below.
Program features