Safe Standstill (Sh) - Siemens SINUMERIK 840D sl Function Manual

03.06
4.2

Safe standstill (SH)

General description
In conjunction with a machine function or in the event of an error, the "safe stand-
still (SH)" function is used to safely disconnect the torque-generating motor power
supply.
When the function is selected, the drive unit is in a "safe status". The power-on
disable function prevents the drive unit from being restarted.
The pulse cancellation function integrated in the Motor Modules is a prerequisite
for this function.
Features of safe standstill
S This function is integrated in the drive, i.e. a higher-level control is not required.
S The function is drive specific. This means that each drive has the function and it
must be individually commissioned.
S The function must be enabled via parameter.
S The terminals for the safe standstill function can be grouped together.
S When the safe standstill function is selected:
– The motor cannot be started accidentally.
– The safety-relevant pulse cancellation interrupts the torque-generating pow-
er-feed to the motor.
– The Motor Module and motor are not electrically isolated.
Caution
!
Appropriate measures must be taken to ensure that the motor does not move
once the motor power supply has been disconnected ("coast down") (e.g. enable
the "Safe brake control" function for a vertical axis).
Caution
!
If two power transistors in the Motor Module (one in the upper and one in the lower
bridge) fail at the same time, this can cause a momentary movement.
The maximum movement can be:
S Synchronous rotary motors: Max. movement = 180° / number of pole pairs
S Synchronous linear motors: Max. movement = pole width
© Siemens AG, 2006. All rights reserved
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 03.2006 Edition
Safety Functions Integrated in the Drive
4.2 Safe standstill (SH)
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