Internal Armature Short-Circuit Braking - Siemens SINAMICS S150 NEMA Operating Instructions Manual

9.3.10.3

Internal armature short-circuit braking

Description
Internal armature short-circuit braking is only available for synchronous motors. It is used
preferably when braking in a hazardous situation, if controlled braking via the drive is no
longer possible (for example, in the event of a power failure, an EMERGENCY OFF, etc.) or
if no regenerative infeed is used. In this case, the motor stator windings are short-circuited
via a half-bridge in the power unit. This means that an additional resistance is inserted in the
motor circuit that supports reducing the kinetic energy of the motor.
The internal armature short circuit is configured via p1231 = 4 and activated via p1230. It is
initiated when the pulses are canceled.
A prerequisite for the use of the internal armature short circuit is the use of a permanent-
magnet synchronous motor (p0300 = 2xx).
Electric shock due to armature short-circuit braking
When the armature short-circuit is active, after the pulses have been cancelled all the motor
terminals are at half the DC link potential.
Contact with live parts can result in death or serious injury.
• Observe the general safety instructions.
Motor accelerates uncontrollably for pulling loads
For pulling loads, for an armature short circuit, the motor can uncontrollably accelerate if a
mechanical brake is not additionally used. If the motor accelerates uncontrollably this can
result in severe injury or death.
• For pulling loads, only use armature short circuit braking to support a mechanical brake
NOTICE
Material damage by using motors that are not short-circuit proof or an incorrectly
dimensioned Power Module/Motor Module
When using motors that are not short-circuit proof, activating the external armature short-
circuit braking can damage the motors or the Power Module/Motor Module.
• Only use motors that are short-circuit proof.
• Use suitable resistors for short-circuiting.
• Dimension the Power Module/Motor Module for 1.8 times the short circuit current of the
Enclosed Drives
Operating Instructions, 12/2018, A5E36652151A
DANGER
WARNING
(a mechanical brake is mandatory).
motor.
Functions, monitoring and protective functions
9.3 Drive functions
541