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What do the brake parameters in Lexium 32 control and how do they effect brake operation?

Published date: 16 September 2019

When commissioning Lexium 32 servo drives there are two parameters that can be adjusted which are related to the "Brake function"

BRK_AddT_Release and BRK_AddT_Apply.

Below is a description of each of these parameters.

BRK_AddT_Release effects the delay time for the drive status to change to “operation enabled”
When drive enable is requested the status bit of the drive will not switch to status 6 (operation enable) until the  BRK_AddT_Release time has elapsed.
Note that the motor torque will be applied immediately when the drive enable is requested and the drive with immediately transition to status 5 (power enabled) but the drive will not allow motion to take place until the drive transitions to status 6 (Operation enable).
Therefore the BRK_AddT_Release parameter effects the delay time between status 5 (power enabled) and status 6 (Operation enabled) of the drive.
This delay prevents motion from taking place until the brake is released and also insures that the motor has holding torque and control of the load before the brake is released.
BRK_AddT_apply effects the delay time for when the “motor torque” is switched off
When disable is requested of the drive to switch the drive off from the enabled state, the BRK_AddT_apply time parameter effects the delay time for when motor torque is removed.
Motor torque, current from the drive, will remain applied after the drive disable and will remain applied until the BRK_AddT_apply  time has elapsed.
It should be noted that when the drive is disabled the drive status bit will immediately transition to status 4 (ready to switch on) but the power amplifier will remain active thereby maintaining current and thereby maintaining holding torque on the motor until the BRK_AddT_apply  time has elapsed
This BRK_AddTapply delay prevents a vertical load from falling by maintaining holding torque on the motor until the brake is known to be applied.
More details…..
All motors that have a brake are subject to a mechanical time in which the physical action of the brake release and brake apply is required (mechanical delay).
When using a Schneider Electric BSH or BMH motor this mechanical delay time is known and included in the motor’s electronic data-plate which is read via the encoder cable over the data communication channel.
This mechanical delay is therefore known by the firmware and the firmware controls drive status transitions automatically.
The parameters BRK_AddT_Release and BRK_AddT_apply are available to allow users to add additional time, if preferred, to the delay of “operation enabled” or “motor torque off”
In addition, the two parameters BRK_AddT_Release and BRK_AddT_ apply which are for BSH or BMH motors and are limited in their respective delay times.
BRK_AddT_Release has a maximum delay of 400ms and BRK_AddT_apply has a maximum delay time of 1000ms
When dealing with 3rd party motors there are two additional parameters which behave exactly as BRK_AddT_Release and BRK_AddT_apply, these two parameters are M_BRK_T_release and M_BRK_T_apply.
These two additional parameters are found in the 3rd party motor configuration section and can be accessed with SoMove commissioning tool.
Because the mechanical delay time for brake apply and brake release of other motor manufacturers is an unknown variable from manufacturer to manufacturer, these parameters are provided in our 3rd party motor setup parameters.
Note that the maximum delay time for these parameters are much higher than the brake parameters for Schneider Electric motors, allowing for a greater range of compatibility of Lexium 32 with other brands of motors.
Also note that there is “overlap” between the parameters BRK_AddT_Release , BRK_AddT_apply found in the basic parameter settings and M_BRK_T_release , M_BRK_T_apply found in the 3rd party motor parameter settings.
For example if a value of 400ms set in the parameter BRK_AddT_Release and 5000ms set in the parameter M_BRK_T_release, then the total time will be 5400ms.
This is also true for the apply parameters.

Therefore when commissioning Lexium 32 for 3rd party motors, you should leave the basic brake parameters set at factory default and focus only on the brake parameters in the 3rd party motor configuration section.

rev 9-16-2019


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