Siemens Simovert Masterdrives Compendium page 888

Control Word and Status Word
Bit 1: OFF2 command (L "OFF2") electrical
Condition
Result
NOTE
Bit 2: OFF3 command (L "OFF3") (fast stop)
Condition
Result
10-2
LOW signal
♦ The inverter pulses are inhibited, and the main contactor
(option)/bypass contactor, if available, are opened.
♦ POWER-ON INHIBIT (008), until the command is removed.
The OFF2 command is simultaneously connected from three sources
(P555, P556 and P557)!
LOW signal
♦ This command has the following results:
• When P290 = 0 (closed-loop current control), the drive is braked
at the current limit by means of torque control (see function
diagram 370). The sign before the braking torque is always
opposite to that of the speed actual value. If the speed actual
value reaches the OFF value P800 (see function diagram 480),
the gating pulse is disabled. If OFF3 is used, the OFF time must
be set to P801 = 0.0.
If brake control is used, P801 must be > P617 + P607. Brake
control (function diagram 470) should not be used together with
AUS3. With brake control the inverter must not be disabled until
the brake is fully applied (i.e. after brake closure time P607 has
exceeded and, if necessary, delay brake threshold P617 → P891
> 0). During this time, the drive would necessarily hum on AUS3
because every sign inversion of the speed actual value (noise to
n , average value of n
act
reverse the torque direction. The brake control should be used
with the AUS1 command.
In the case of drives with a low moment of inertia in comparison
to the motor moment of inertia, it may be necessary to increase
the OFF value P800 by up to 1 to 5 %. If this is not sufficient in
order to avoid fluctuation of the torque-forming current setpoint
when n ≈ 0, a speed-controlled shutdown with OFF1 must be
carried out. The torque limits (K0172, K0173) have no effect
during OFF3. The torque can only be limited by means of P128
(maximum current).
When P290 = 1 (v/f characteristic), the setpoint at the ramp-
function-generator input is blocked so that the drive is powered
down on the parameterized deceleration ramp (P464) to the OFF
frequency (800).
After the OFF waiting time (P801) has expired, the inverter
pulses are inhibited and the main/bypass contactor, if present, is
opened. If the OFF3 command is withdrawn during deceleration,
deceleration is nevertheless continued.
= 0 if brake is applied) would also
act
6SE7087-6QX70 (Version AG)
Compendium Motion Control
05.2006
Siemens AG
SIMOVERT MASTERDRIVES