Drawbridge motor & controller upgrades

[markac]

Does anyone have experience with upgrading the control system & drive motor for a motor operated drawbridge? We are investigating upgrades to an existing drawbridge that uses a 30 HP wound rotor motor and a resistor bank for speed control. Is anyone familiar with using an "off the shelf" induction motor for such an application, & what sort of control system is typically used? I would welcome any ideas and recommendations.

 

[RadarRay]

I have never seen a drawbridge drive but I don't see why you cannot use an AC drive for this. You have to make sure all the safety interlocks are in place. More importantly, when lowering the bridge, the drive will most likely be regenerating and it may be doing this rather heavily. This energy will have to go somewhere and you only have two choices. An active front end (regenerative) which will put the power back on the line or DB resistors. If DB is the choice, it is unlikely the standard DB circuit in an AC drive can handle this load so you should take great care that both the DB resistors and the IBGT for braking are sized correctly. I would think you would have to supply an external braking controller for this.
I have to assume there is some kind of mechanical brake with interlocking, similar to what would be on a hoist drive for safety.

 

[xnuke]

A company I used to work for did stuff like this. You may want to check out this application note:

http://www.systems-interface.com/ver4/app/montlake.pdf

I am in no way trying to promote their services, this is just a project I knew about.

xnuke

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