12 replies to this topic

[liftmech]

Jeff (kicking horse) asked me about this and I thought I would expand upon the topic.
On any random lift, when you press the stop button there are several things that will slow and stop the lift.
Some lifts utilise a regenerative drive; this is where the drive actually slows and stops the lift using reverse current to the motor(s). In that instance, the service brake merely holds the load of the lift after it has come to a stop.
Others dial back the current supplied to the motor until it reaches zero, at the same time that the service brake is closing. In this case it is the brake that actually stops the lift.
Emergency stops are a different beast. By code an emergency stop cuts power to the motor completely (or shuts off the diesel engine) and drops the emergency and service brakes at the same time. On a lift that does not use a regen drive, this results in a much shorter (and more abrupt) stop. On lifts that do have a regen drive, the stopping distance is somewhat longer than a normal stop because the braking capabilities of the drive are no longer part of the equation.

[highspeedquad]

That provides a great deal of detail. I found it very helpful as to how the lift stops. When a safety gate is tripped, which brake is activated?

[Allan]

Safety gates are service stops.

[Duck]

The term regenerative in other industries usually means the current generated by the motor (now acting as a generator) is passed through a load (ie. resistor bank). Is that what they do on lifts? Or do they actually drive the motor in reverse?

-Iain

[Aussierob]

Duck, on Mar 1 2005, 10:37 AM, said:

The term regenerative in other industries usually means the current generated by the motor (now acting as a generator) is passed through a load (ie. resistor bank).  Is that what they do on lifts?  Or do they actually drive the motor in reverse?

-Iain
<{POST_SNAPBACK}>

Ski lift drives usually apply power in reverse to slow the motor. Technically this is plug braking but is usually called regenerative braking. On a Doppelmayr the safety gate fault causes a ramp stop(regen stop).

[Allan]

Someone else from a resort in BC!! :) Welcome Aussierob! One of our YANs does a regen stop for the safety gate too.

[Kicking Horse]

a stop gate stop should be a service stop no need for a e-stop to take place,,,

[Aussierob]

Allan, on Mar 1 2005, 12:10 PM, said:

Someone else from a resort in BC!! :) Welcome Aussierob!  One of our YANs does a regen stop for the safety gate too.
<{POST_SNAPBACK}>

Hi, Just found this site last week. Kinda wish I knew about it sooner. I'm
a maintenance electrician at Whistler blackcomb (10 years now). I heard you guys did a retro with a non regen drive. We just replaced all the controls and drive on Crystal chair last summer. It's a thing of beauty. (now we got all the bugs out :P )
Rob

[Allan]

We got rid of the B10 stuff out of both our YANs, and got rid of the HV controls out of one of them (the non regen lift) and kept the Sabina regen unit in the other.

[liftmech]

We have no regen on our Yans, but we also still have all the Base 10 drives. We also have two way old 4200 'Black Death' units retro'ed with Base 10 drives; from what our sparkies tell me they were a bear to work with before the change. All of our Pomas have regen drives, either BBC or ABB.

[Matt]

What regen method is the most common? Do they actually have an inverter that dumps power back into the grid or do they short out the armature? Or do they reverse the motor ("plugging" it, as Aussierob mentioned.)

[Aussierob]

It's almost aways plugging (applying power in reverse). A full regen set is very expensive as you need another set of thyristors (power semiconductors). In a ski lift application the lift doesn't "drive" the motor that often so its not worth the extra cost, even though the energy produced goes back to the grid.

[liftmech]

As far as I can tell, the B10/4200 hybrids work just fine. Having one common drive reduces inventory and makes troubleshooting easier.