Siemens SINAMICS S150 Operating Instructions Manual page 294

Setpoint channel and closed-loop control
7.4 Vector speed/torque control with/without encoder
Short-circuit protection
For short circuits that can occur in the drive converter or in the motor cable, the rotating
machine would supply the short-circuit until it comes to a standstill. An output contactor can
be used for protection. This should be located as close as possible to the motor. This is
particularly necessary if the motor can still be driven by the load when a fault develops. The
contactor must be provided with a protective circuit against overvoltage on the motor side so
that the motor winding is not damaged as a result of the shutdown.
Control signal r0863.1 is used to control the contactor via a free digital output; the checkback
contact of the contactor is connected to parameter p0864 via a free digital input.
This means that if the drive converter develops a fault with a shutdown response, at the
instant in time that the pulses are inhibited, the motor is isolated from the drive converter so
that energy is not fed back to the fault location.
Function diagram
FD 4715
FD 6721
FD 6724
FD 6731
294
Actual speed value and rotor pos. meas., motor enc. ASM/SM (encoder 1)
Current control - Id setpoint (PEM, p0300 = 2)
Current control – field weakening controller (PEM, p0300 = 2)
Current control - interface to Motor Module (PEM, p0300 = 2)
Drive converter cabinet units
Operating Instructions, 07/07, A5E00288214A