What kind of VFD, can be used in the Crane and Fork Lift Application? Please include Elevator application as well.

Hello Ramasubramanian

Welcome to the forum.


I am not sure what sort of answer you are looking for with this question.
For a start, the crane, forklift and elevator are wildly different machines and have very different requirements, for example a forklift typically is battery powered and the others are mains powered.

Please be more specific with your question.

Best regards,

Dear

i am working in a company which has its own drives.And yes we do have dedicated drives for the Lift ,escalator.

if ur really interested then u can contact me on rahuljadhav1@rediffmail.com

regards

Rahul Jadhav

Hello Ramasubramanian,



Creane and elevator usually mains powered , and frequency inverter is important part of control devices used in control panel.
Best frequency inverter for precise application in the market you can find on the link

http://www.nfodrives.se/

Best Regards
Takhinen

Actually I have the same question. I have specified and installed VFDs for pumps, however my question is: Is that a good practice to control a Slip Ring Motor which used in cranes and hoists by VFD?

Thanks for help

The biggest challenge to applying VFDs to any lifting or hoisting application is in what to do when the mechanical brakes are released. If the VFD is not already providing torque at that moment, the load will begin to drop and the motor may be unable to overcome that extra inertia. With an older slip-ring motor, they would have a resistance value predetermined (by trial and error usually) to provide sufficient torque just before the brake is released, then control the ascent or descent by varying the resistance to the rotor. With a VFD you are eliminating that rotor control and substituting stator control to provide torque. But it takes a microprocessor a few scans to calculate the proper vector algorithm and if the VFD hiccups for even a brief moment, the load can run away on you. So using Closed Loop Vector drives, the crane and hoist VFD industry has developed what are called "torque proving" features which provide full torque necessary to hold the load before the brake is released. If you are an experienced VFD engineer with a lot of time and a very understanding boss, you could experiment with this concept on your own. A better plan is to use a VFD designed specifically for crane and hoist applications that already has this capability built-in and then hire an experienced applications engineer to assist you. I would not recommend any other option.

By the way, the elevator industry is exactly the same, but VFDs for elevators usually fall under more stringent regulatory issues because they involve moving people, not things.

Note: I do not believe the suppliers who claim to be able to do this without a Closed Loop Vector drive. If they want to sell you one, ask if they are willing to stand underneath your heavy load when you release the brake!