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9.3.10.2
External armature short-circuit braking
Description
External armature short circuit braking is only available for synchronous motors. It is used
preferably when braking in an emergency, 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
external braking resistors. This creates additional resistance in the motor circuit, which helps
reduce the kinetic energy of the motor.
The external armature short circuit is activated via p1231 = 1 (with contactor feedback
signal) or p1231 = 2 (without contactor feedback signal). It is initiated when the pulses are
suppressed.
This function uses output terminals to control an external contactor, which then short-circuits
the motor through resistors when the pulses are suppressed.
A prerequisite for the use of the external armature short circuit is the use of a permanent-
magnet synchronous motor (p0300 = 2xx).
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
Property damage due to use of motors that are not short-circuit proof
When using motors that are not short-circuit proof, activating the external armature short-
circuit braking can damage these motors.
• Only use motors that are short-circuit proof.
• Use suitable resistances for the short-circuiting.
Note
Consequences of incorrect configuration
In case of incorrect configuration (e.g., induction motor and external armature short-circuit
selected), fault F07906 "Armature short circuit/internal voltage protection: Parameterization
error" is generated.
Function diagram
FP 7014
Converter cabinet units
Operating Instructions, 11/2017, A5E36652151A
WARNING
(a mechanical brake is mandatory).
Technology function - External armature short circuit
Functions, monitoring and protective functions
9.3 Drive functions
521
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