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Elevator Core Reference Guide

Torque Reduction during Stopping Feature

Torque Reduction During Stopping

During stopping when the motor brake applies and the motor current is immediately removed a noise can sometimes be heard in the lift cabin, to help solve this problem parameter P4-17 can be adjusted so that the current is ramped down rather than switching the current sharply off, this is used in Gearless Permanent Magnet motor applications.

Torque Reduction During Stopping - Operation

Setting Torque Reduction During Stopping

  1. Commission the drive as normal

  2. Set P4-17 to the required torque reduction time

    Note

    The best value is one where there is enough time to properly reduce the torque but not to long so that the Safety Chain opens before the torque reduction has finished.

  3. To see exactly when the torque reduction happens in your sequence use P0-35 to show the travel profile states.

Torque Reduction During Stopping Timing Diagram

Features_and_Functions_-_Torque_Reduction.svg

Important

When operating with an Induction motor P4-01 = 0, 1 or 2, the drive uses an internal value of 100ms and P4-17 has no effect.

Torque Reduction During Stopping Parameters

Parameter Number

Parameter Name

Units

Default

Available Settings

Access

Change During Run

Scaling

Size (Bytes)

CAN Register

CAN Sub Index

Modbus Register

P4-17

Torque Reduction time during stopping

sec

1.0s

0.0 ... 10.0s

RW

Y

1 = 0.1s

1

21A1h

0

417

P4-17 - Torque Reduction time during stopping

Setting the parameter to 0.0s means the function is disabled. This parameter helps in reducing the noise in the lift car when the motor brake is applied due to the immediate removal of current. Increasing this value reduces audible noise, setting too high can result in reduced torque and rollback during stopping.

This parameter has no effect when operating in an IM or V/F control mode (P4-01 = 0, 1 or 2) and the torque reduction time is fixed at 100ms.

Torque Reduction During Stopping FAQ

Below is the answers to some commonly asked questions about the Torque Reduction during Stopping function.

Question

Answer

How do I change the length of the torque drop off time?

Use P4-17 to set the time of the torque drop off

How to tell when the drive is performing torque reduction?

Normally the torque drop off is the last step in the sequence.

The exact time can be viewed with the Travel Profile State in Parameter P0-35. The state for Torque Reduction is 49.

Why does the drive trip STO-L before the torque drop off time has finished

If the torque reduction time in P4-17 is set to long then the controller may open the safety chain before the torque reduction is finished being causing an STO-L trip. The solution to this is to reduce the time in P4-17.

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