Visit the Procter Machinery Guarding web site

Lift system is safe enough for the HSE

Edited by the Engineeringtalk editorial team Jun 5, 2003

The revolutionary noncontacting USP lift positioning system has been installed in the London offices of the Health and Safety Executive.

Schmersal's revolutionary new noncontacting USP lift positioning system has been installed in the London offices of the Health and Safety Executive.

An 11-storey office block near London's Southwark Bridge that is the headquarters of the Health and Safety Executive has been fitted with five new USP lift positioning systems from Schmersal, a leading manufacturer of machine safety equipment.

The installation, which was started in October 2002, was part of a contract awarded to Accord Lift Services to modernise the five-car group of lifts that serve the building's 11 floors.

The modernisation also included changing the lift controls and door gear motors for all five cars, while retaining the original hall lantern and position indicator system.

Says a spokesman for Accord: "As this is a higher-rise building with a fast lift speed of 2m/s we asked Lester Controls, our preferred equipment supplier, if we could use a shaft positioning device rather than the traditional tape head system".

Lester Controls contacted Schmersal, whose Area Sales Manager Terry Reay suggested this would be an ideal application for the USP lift positioning system.

Explains Reay: "The USP system is a very cost efficient solution for travel heights from 30 to 130m and lift speeds up to 8m/s, and installation time is only about an hour".

The system consists of a transmitter mounted on the cabin and a receiver that can be fitted to either the shaft pit or shaft head.

Transmitter and receiver are linked by a specially designed signal wire that has one damper fitted at the receiver end and another fixed at the bottom end of the shaft.

Swing protection units are also fitted.

The noncontact operating principle used by USP to position elevator cabins, eliminates conventional switching technology and common encoder systems.

It operates by sending a trigger impulse from the receiver through the travel cable to the transmitter, which then generates a non-contact ultrasonic pulse in the signal wire that expands in both directions towards shaft pit and shaft head.

The receiver's microprocessor system, which is able to communicate with the latest control systems, converts the mechanical pulse into an electronic positioning value that can be detected as serial data information by the control unit.

The pulse is then neutralised by both dampers.

The positioning value can be recalled at any time, even after a power cut.

As this was Accord's first installation of a USP system in the UK, a Schmersal applications engineer flew in especially to offer help and advice to the engineering team.

Commenting for Lester Controls Mike Turner says: "Everything went very smoothly.

Schmersal monitored the installation of the first system, I was on site for the second system, and after that the Accord engineers were sufficiently experienced to install USP for the remaining three lifts".

On the advantages of the USP system, he says: "Accuracy and ease of installation and programming are the most impressive features.

The one hour installation time is very fast compared to traditional systems, and programming of floor levels, slow-down points and other parameters via the USP's interface panel is very simple".

"Positioning is very accurate and very consistent".

He adds: "Slow down points work every time and floor positioning is accurate to +/-1mm".

Accord and Lester Controls were also very impressed with Schmersal's customer service throughout the project, and report that reliability has been exceptional, with no problems or breakdowns in the system in the six months since it was installed.

Commenting for Schmersal, managing director Terry Hayward says he is delighted to have a USP system installed in such a prestigious site.