The lifts in the 14 storey Peel House building in Manchester have been refurbished using a pioneering control technology that is more effective than conventional approaches.
“The refurbishment had become urgent,” explains John Bentley, managing director of Manchester-based ANSA Elevators, “and so the client approached us knowing of our reputation for a fast turn-around.”
Bentley approached Lifteknic, a controller manufacturer of Mold in Flintshire, which offered a direct-to-floor system based on Control Techniques’ Unidrive SP.
Previously, in the independent lift suppliers market, the norm has been a ‘creep-to-floor’ control profile, where a series of shaft encoders return position signals to the controller, indicating when to slow to creep speed (typically a drop from 2 m/s down to 0,5 m/s). The creep time is anything up to 4 seconds, when a second signal from a shaft encoder initiates a ramp to stop, which is based on time.
By contrast, a direct-to-floor profile uses a drive in speed mode which is changed to position mode (essentially servo control), initiated by correction sensors located, in this case, 430 mm above and below each floor. Any error in position is corrected constantly, giving high accuracy, reduced floor-to-floor times and a high quality smooth ride.
“This is only part of the story,” adds Bentley. “Conventional thinking has dictated that gearless lift systems, which do not have the benefit of geared ratios to improve a drive’s effective response, need to have a load weighing device to provide the lift controller or variable speed drive with a torque feed forward signal. In other words, most drives are too slow! We have found that, with Control Techniques Unidrive SP drives, the response is so fast and accurate that the load-weighing device is redundant. Add to that the savings on sensors and it all adds up to a lower cost high performance system that is quick and easy to install.”
The lift control system at Peel House is based on a Unidrive SP AC drive with a 22 kW synchronous permanent magnet gearless AC motor working in conjunction with the Lifteknic Quatrain control system.
The drive is fitted with an application module programmed with the Control Techniques direct-to-floor software program and accepts Sin/Cos feedback from a motor mounted encoder that gives a resolution of more than 4 million ppr – a key factor in eliminating the load weighing device.
“The Unidrive SP from Control Techniques offers the independent market a technical and performance advantage over the more traditional lifts suppliers,” he says. “We now have a more advanced product to offer with networking, direct-to-floor capability, better ride quality and better reliability too.
“And, this solution saves on a major cost – the load weighing device – as well as reducing the number of in-shaft sensors, which cuts installation time and cost.”
A key concern for building owners and elevator contractors is public safety and the ability to get elevator passengers rescued during a catastrophic power outage. The solution built into every Unidrive SP is a 48 VDC back-up power supply connection. In the event of a power loss, connection of a simple 48 V UPS allows full load operation of the elevator’s motor at a slow speed.
Finally and crucially for the lift industry, Unidrive SP includes as standard, a ‘secure disable’ function, which meets the requirements of EN954-1 category 3 for the prevention of motor operation. This can be used as the ultimate control function in a safety interlock system; it replaces up to two safety contactors, saving money on both equipment and installation costs.
“Unidrive SP offers the independents the opportunity to offer a better solution at a reduced ownership cost,” concludes Bentley.
For more information contact Bill Tedd, Control Techniques, +27 (0)11 462 1740, bill.tedd@emerson.com, www.controltechniques.com
| Tel: | +27 11 462 1740 |
| Email: | samantha.correia@mail.nidec.com |
| www: | www.controltechniques.com |
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