Efficient Networks S120 manual 191

Basic functions

6.8Armature short-circuit brake, internal voltage protection, DC brake

6.8Armature short-circuit brake, internal voltage protection, DC brake

Features

●For permanent magnet synchronous motors

–Controlling an external armature short-circuit configuration

–Controlling an internal armature short-circuit configuration (booksize)

–Internal voltage protection (booksize)

Note

The "internal voltage protection" function can only be used for modules with DAC processor.

The usable booksize modules are identified by the code A3 at the end of their MLFB, e.g. 6SL3130-6TE21-6AA3. The booksize Compact modules are universally usable.

●For induction motors

–Control of a DC brake (booksize, chassis)

●Configuration via parameter (p1231)

●Status message using a parameter (r1239)

Description

The armature short-circuit, internal voltage protection and DC brake functions cannot be simultaneously activated. The functions are selected individually via parameter p1231.

Armature short-circuit braking is only available for synchronous motors. They are mainly required when braking in a hazardous situation, if controlled braking using the drive converter is no longer possible, e.g. when the power fails, EMERGENCY STOP etc. or if a non-regenerative feedback infeed is used. In this case, the motor stator windings are short- circuited - either internally or via external braking resistors. This means that an additional resistance is inserted in the motor circuit that supports reducing the kinetic energy of the motor.

In order that the drive remains in closed-loop control during voltage dips and failures, a buffered 24 V power supply (UPS) must be used. High-speed permanent-magnet spindle drives for machine tools are a typical application for armature short-circuit braking.

The functions can be initiated with a "1" signal at binector input p1230. Initially, the pulses are canceled and then the armature is short-circuited or the voltage protection. Using r0046.4, the initiation of these functions via p1230 can be checked.

One of the advantages of an internal armature short-circuit brake is the superior response time of only a few ms. The response time of a mechanical brake is about 40 ms. With the external armature short-circuit brake, the slow contactor response causes a response in the range of > 60 ms.

The DC brake is only suitable for induction motors and is comparable with the internal armature short-circuit for synchronous motors. The DC brake works with Motor Modules of both booksize or chassis type.

Drive Functions	191
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4