Skilifts.org / SORT Forum

ABB is a drive manufacturer, they build AC and DC variable speed drives that are used in many lifts. A drive has to be "commissioned", which is part of an acceptance test on a new or modified lift. This means there will be documentation on exactly how the drive was configured. Having said that.....................Let's wait until the CPTSB releases their report.

Wow - how the bullwheel turns. There needed to be a redundant system that monitored the acceleration/deceleration of the lift. I'm very curious of the outcome of this investigation.

The 800 series drives from ABB don't come with ramp monitoring or speed measurement error.
This post has been edited by 2milehi: 10 January 2017 - 07:49 PM

The ABB DCS 800 has a speed feed back fault It's #522. It will trip if measured speed and calculated speed from EMF are different.

_litz, on 10 January 2017 - 04:42 PM, said:

Don't know who it was that installed it, but it wasn't Bald Eagle Lifts. Haven't ever sold anything to Granby.

Thanks

Aussierob, on 11 January 2017 - 01:45 PM, said:

We have a DSC800 that was installed by Doppelmayr 4 years ago on a 1991 fixed grip. The lift ran away and didn't fault with a speed feedback fault (no people were on-line). The issue was with the full wave rectifier where the tach signal comes into the Doppelmayr controls. A diode in the full wave rectifier was acting like a zener diode and only allowed no more that 100 volt through. The 110% on the line speed meter would not have tripped due to this problem.

When the lift was commanded to a fast from a medium speed the drive was seeing the clipped tach voltage at roughly a 1000 rpm. When the drive tried to ramp past 1000 rpm, the tach signal didn't change and that's when the drive poured on the coals. The drive doubled the speed of the lift (roughly 3.5 m/s) in two seconds. A chair that had two feet of snow on it went around the bullwheel and flung off all the snow. Myself and a mechanic frantically hit every stop within reach. The drive did not fault out. The speed measurement error did not work.

I replaced the rectifier board with another one and all was fine. I talked with both Doppelmayr and ABB about this issue and got nowhere. We installed a PLC to do ramp monitoring and overspeed.
This post has been edited by 2milehi: 11 January 2017 - 07:20 PM

Let me clarify what I mean by "speed measurement error" fault. The drive has a programmed ramp from zero speed to max motor rpms. The tach should produce the same ramp when the motor is commanded to ramp up. Speed measurement error is the different between the programmed ramp and actual speed.

Wayback became a HSQ for a few moments, eh?

iceberg210, on 11 January 2017 - 03:46 PM, said:

Erik - Peter updated his article accordingly. Many thanks to whomever edited my quote from Peter's article to match.

_litz, on 11 January 2017 - 09:15 PM, said:

Yep I got a hold of him and he got on it asap.
Thanks

2milehi, on 11 January 2017 - 07:27 PM, said:

So you're actually talking about a reference-actual deviation fault in the lift controls. Also with regards to the incident you mentioned, the tach signal should go directly to the drive, not through the rectifier Doppelmayr uses for the speed meter. As well, hitting the stops should drop out the main contactors, killing the power to the drive (or motor depending on where the contactors are located.)

The lift I am talking about (Wayback) has relay logic, there is no PLC that was originally installed (1991). I am strictly speaking about the ABB drive.

I discussed this topic last year in the below post. The signal from the tach on the motor is shared between the controls AND the drive. There is only one signal from the motor tach because there is only one tach.

http://www.skilifts....showtopic=10469

All of the lifts I've done have relay logic and canadian code requires a reference-actual deviation fault to be installed with a new drive. This is all wired outside the drive.

So we are talking about two different things. About two years ago Colorado required ANSI's ramp monitor to be added to any new drive installation.

Per Peter, Quickdraw is getting a new drive from LP and has been closed again for additional testing.


https://liftblog.com...t-granby-ranch/

In reading an article on a local news site it makes it sound that this recent closure is a result of observed irregular operation... Presumably while on the Diesel drive with the electric motor completely disconnected...?

http://www.9news.com...-fall/389337867

From the article:
The lift was closed while state regulators investigated. The Colorado Passenger Tramway Safety Board allowed it to reopen on Jan. 10 but required that it be operated by a diesel engine rather than the electrical unit that is believed to have malfunctioned.

The ski area shut it down again on Wednesday. According to Lee Rasizer, a spokesman for the state board, the decision was made after the lift experienced “unusual/irregular conditions.”

At an emergency meeting Friday, the board ordered that the lift remain closed “until deemed safe.”
This post has been edited by RibStaThiok: 20 January 2017 - 09:16 PM

2milehi, on 13 January 2017 - 07:51 PM, said:

What type of ramp monitor device does Colorado require? Is it an ANSI numbered device? Something like this? https://www.sick.com...n_IM0047459.PDF

Highlights from an article that appeared in the past 12 hours:

More testing.
- officials now say that testing will continue through Tuesday."
- the lift was closed on Wednesday, January 18 after what Granby Ranch called, "unusual/irregular conditions in the performance of the diesel prime mover system."

http://www.thedenver...for-2-more-days

And the installation of the new electric drive is now commencing..


GRANBY, Colo. – Ski Granby Ranch will be installing a new electric lift drive on the Quick Draw Express Lift, hoping to have the lift back up and running by this weekend.
On Wednesday evening, the Colorado Department of Regulatory Agency issued an amended agreement for the ski resort.
It states Granby Ranch can go ahead and reopen the Quick Draw Express Lift once it passes a Colorado Passenger Tramway Safety Board (CPTSB) inspection. That inspection will be scheduled once the ski area has made "necessary alterations required to reopen under terms of the amended agreement."
Once it reopens, the ski area will have the following conditions in place:

• The operator will continue to leave the lift disconnected from the electrical drive and will continue to operate the lift with the diesel prime mover only.
  
• Operator will mechanically modify the lift to stabilize and remove dynamics from the lift -- the lift cannot reopen until it passes dynamic acceptance testing and inspection by the board.
  
• Operator will increase surveillance and inspection of the lift
  
• Mechanics will visually inspect the top terminal, power the lift, supervise the operational pre-operation checks and ride the entire line in both directions
  
• Ski patrol and operators will ride the up-side line together as part of every check
  
• The rate capacity of the diesel motor is 900 feet per minute. Operator will operate the lift at speeds within operational capacity and below state-approved maximums: up to 600 feet per minute for two days after reopening; up to but not more than 700 feet per minute beginning on the third day after reopening the lift and continuing thereafter
  
• Ground inspections and ride checks will be conducted each day during regular lift operations at 11 a.m., 1 p.m., 3 p.m., 5 p.m. and 7 p.m.

The new agreement comes nearly a month after a Texas mother lost her life when she fell 25 feet onto hard-packed snow. Her two daughters, 9- and 12-years-old, were injured but survived the fall.

The Colorado Passenger Tramway Safety Board blamed the incident on a “rare dynamic event” within the lift’s primary electric drive.
The board has yet to complete its investigation into the incident.
Leitner-Poma of America, the lift’s original manufacturer, will install the new electric drive, according to Granby Ranch officials.
The ski area said on Jan. 20 that an independent contractor was hired to make modifications to the lift before the current ski season, and that "the issue that likely caused the incident was the independent contractor's modification to the lift's electrical drive/control system."
After the incident, Granby Ranch operated the lift on diesel power but closed it again on Jan. 18 after what Granby Ranch called, "unusual/irregular conditions in the performance of the diesel prime mover system."
The ski area is working with the board to have the lift re-approved for diesel operation while the electric drive is installed, and officials hope to have the lift re-start on diesel power by this coming weekend.
“The ski area has targeted the week of January 30^th to renew operation of the lift on electric power,” Granby Ranch officials said in a press release. “Once installed, the lift will be off-line for up to 48 hours while it is inspected and tested by the Tramway Board.”

The Quick Draw Express will not be in operation on Wednesday and Thursday of this week while officials perform testing on the lift, officials said on Facebook.
The Conquest, Milestone and Kicking Horse lifts remain in operation.

If this was a result of an independent contractors work. Why then did the area continue operations of the lift when said lift was having continues problems day prior and hours before this tragic accident happened? In my opinion the areas operating procedures should be looked at and not the work of a independent contractor. Train your staff to recognize problems, troubleshoot, convey issues to management... stand up for what's right and what's wrong, and not just hit reset, or show management where the reset button is.
This post has been edited by towertop: 26 January 2017 - 06:06 AM

Aha, source material ..... http://www.aspentime...rlift-incident/

Work continues on the new electric drive, and they are attempting to receive permission to restart operations under diesel, pending completion of the electric drive, and following that completion, a full re-certification for normal operation.

Very confusing, because the text is exactly identical to the original order; makes it seem like they're just trying to return the original diesel only operation. shrug ... the safety board knows what's going on, that's what counts.

Our of curiosity, how fast can an "electric drive" be installed? We aren't exactly talking about a small amount, or small size, of equipment here ... lifts are big mommas, in the power world. Lots of current, lots of voltage, and lots of power ... and apparently lots of very delicate and tricky electronics.
This post has been edited by _litz: 26 January 2017 - 03:26 PM