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Old November 23rd, 2017, 11:06 PM   #1
smartatuls
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Motor runs before brake opening

Hi,

We have a EOT crane which has 3 hoists (30T/60T/30T). The issue is when we give command for Hoist Up or Down the the motor runs for few rotations then stops completely and after full opening of brake it starts running again. Not sure how this is happening.
There are 2 Thruster brakes for each hoist, their opening and closing works together. The brake open/close command is given by drive output relay. The drive is ATV71 - Schneider which has inbuilt brake logic parameters.
We never faced such problem . This is something new.
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Old November 24th, 2017, 12:20 AM   #2
goghie
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You didn't provide enough information. How is supplied electro-hydraulic thruster? Is output relay on or off when you start hoisting and there is problem? What is state of brake shoes and drum? etc...
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Old November 24th, 2017, 12:21 AM   #3
GaryS
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Is this a new installation or has it been running for while and just started showing this.

is the first short motion in the up direction no matter witch direction command is entered
Example down command entered the motor first runs in the up direction a few turns then the brake is energized, released then the motor runs in the down direction ( Lower the load )
if this is the case then it looks like they are doing a proof of torque before releasing the brake and the drive need to be adjusted or the brake is not holding correctly and should be repaired before you drop a load.
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Old November 24th, 2017, 02:15 AM   #4
cardosocea
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The motor trying to move with the brake closed doesn't surprise me in the slightest. I've worked with pretty big winches and they all worked like that.

You turn the drive into torque control, apply a set point and because the brakes are applied, the motor will torque to that value. If you have load cells installed, you can even calculate roughly the amount of torque you require and apply that to avoid any movement of the load (the drives should be fast adjusting the torque, but it's a better result this way).

What surprises me is that it is capable of moving. Have you noticed something odd when applying the brakes that would explain the loose wire?
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Old November 24th, 2017, 05:14 AM   #5
smartatuls
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While closing brakes it works perfect. Issue is only for opening brakes.
I got to know that someone has played with Brake Release Time setting. I need to check back the same.
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