Thursday, 12 December 2019
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UCM recognition according to EN 81-20

The door zone area is the one of the areas of a lift most in need of monitoring and therefore has to be considered with considerable care in relation to its safety.

The UCM-01 module from RST Elektronik. (Photo: © RST Elektronik)

Amendment 3 of EN81-1/2 dealt with this hazard area and now presents the lift industry with new challenges. A certified detection installation is required in order to be able to detect unintended car movement (UCM) in the zone area when the lift car doors are open.

Safe UCM detection

The UCM-01 module from RST Elektronik provides safe UCM detection in the form of a space-saving electronic solution independent of the control device, which can be used both in cable and hydraulic lifts and universally in modernisations and new construction. The device records the movement and speed of the lift car from the beginning of a trip, using two independent evaluation channels.

If the door contact is interrupted and the threshold value of speed or route is exceeded, the redundant safety relays of the electronics and the downstream actors in the safety circuit of the lift are switched off and the lift halted.

Consequently, in cooperation with certified detectors (encoder systems) the UCM-01 module of RST Elektronik can adopt the triggering of certified client actors (brake, safety catch, pressure shutoff valves, redundant lowering valves, cable brakes, etc.).

Function test

The function test of the UCM-01 module when installed is very user-friendly, since the UCM error case can be simulated simply by disconnecting a plug. The operator is shown all relevant information via an integrated clear text display, which permits targeted evaluation of the overall system when triggered.

The information collected is very helpful for precise diagnosis during the acceptance test of the lift by a certified body. In addition, the data obtained can be used for lift documentation and provide the fitter with maximum transparency.

UCM-01 module in "lift" system

A redundant encoder system is used to meet the requirements of the standard, which is connected directly to the UCM-01 module and can simultaneously be used as shaft copying for the lift control. The evaluation of path and speed guarantees that in the event of a UCM error, only a minimal car movement occurs. Particularly in the case of fast "slipping" of the car, the speed trigger ensures that the path travelled before shut-down is much shorter than in a path-dependent procedure.

In other words, permanent monitoring is ensured, not only when leaving the zone area, but also in the zone area itself. An important advantage of this technology is that the actors in the zone area can remain connected to power. This opens up new application options due to the short switching cycles and associated reduction in noise level.

The following advantages also arise:
• autonomous operation, since universally deployable for almost every control
• use in lifts according to EN81-1/2 and EN81-20/50
• certified emergency stop installations
• no negative impairment of the readjustment
• can be used for hydraulic and cable lifts
• compact design and low space requirement thanks to processor-controlled operation
• start-up without additional parameter assignment effort
• very fast shutdown through permanent monitoring in zone area
• storage of errors in device
• clear-text display for presenting important information, such as trigger cause, path travelled and maximum speed achieved in the event of an error
• easy testing option for entire system
• use of the system up to a conveyance height of 55 m and speed of 3.5 m/s
• speed- and path-dependent monitoring
• type-tested

Retrofittable solution

With the UCM-01 module the customer receives a forward-looking and retrofittable solution with a maximum degree of safety. Apart from the certified actors, the UCM-01 module, redundant encoder system, belts and accompanying belt break monitoring along with all attachments needed and connection cable can be obtained as a package from RST Elektronik.

The system mentioned can be supplemented with other innovative products from RST, such as a lift control with its specially-developed microprocessor IMC-2, frequency converters, drives, landing fixtures or the new IMC-2 monitoring system.

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