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Signode
Power-User

Join Date: Aug 2007
Location: Lahore
Posts: 369

Problem with Danfoss Inverter VLT-5000

07/20/2011 6:05 AM

Dear Friends;

We have installed a Danfoss inverter VLT-5000 to drive a 30KW fly wheel connected motor at die cut machine. Max freq programmed is 22HZ and idle speed set is 7HZ. There is a clutch between fly wheel and machine. First operator starts the motor (start contact at terminal 18) and it runs at 7HZ then he runs the machine (clutch engages and Freeze Reference contact engages at terminal 29 which enables speed up/dn) and increases the speed up to 22HZ. At this stage, if he stops the machine, clutch disengages and contact "Freeze Reference" also breaks. Now motor quickly decelerate to zero and then 7HZ but during this operation, an alarm message appears "Brake IGBT fault-WARN 27". The alarm message blinks but during this, motor remains operational.

I need information how to control on this problem. We have connected brake resistance 13.5OHM-10,000W with inverter.

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JRaef
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United States - Member - New Member Engineering Fields - Power Engineering - New Member

Join Date: Sep 2006
Location: California, USA, where the Godless live next door to God.
Posts: 4665
Good Answers: 804
#1

Re: Problem with Danfoss Inverter VLT-5000

07/20/2011 2:13 PM

It is telling you that your Baking transistor is about to fail or has already done so. You are trying to stop the flywheel and most likely the braking capacity of the VFD is inadequate to accomplish this. Did someone engineer this carefully or did someone just ASSume it was OK to try to stop a flywheel load with a standard VFD?

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Johny451
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Join Date: Aug 2008
Location: Melbourne, Australia
Posts: 476
Good Answers: 32
#2

Re: Problem with Danfoss Inverter VLT-5000

07/20/2011 10:33 PM

"Brake IGBT fault-WARN 27" indicates that the Brake IGBT transistor has short-circuited. This is a pretty serious warning as it means that the Brake resistor is taking a lot of power - it may have been saved by another trip (Brake resistor thermo cutout) that protects it.

Anyway the VFD needs a service guy to fix it.

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Plugg
Member

Join Date: Jul 2010
Posts: 9
#3

Re: Problem with Danfoss Inverter VLT-5000

07/21/2011 3:17 AM

When using a suitable brake resistor in a Danfoss 5000 unit, you need to set an appropriate ramp down time, to allow the unit to cope with the available machine power caused by the system inertia. This can be done by checking the dc link voltage display and increasing the ramp down time to drop this voltage to a tolerable level, generally ramp down time is more than twice the required ramp up time.
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