New shaft copying and safety system for elevators from Treotham

The latest product in Treotham’s Elgo LIMAX series is the LIMAX2CP safety sensor, which combines recording of the absolute shaft position and speed and various safety functions in one housing. CP stands for compact. The new sensor is of special interest for efficient shaft measurements. Even for a compact device, it is extremely small at 374.5 x 120 x 40 mm.

Apart from conventional safety functions, such as overspeed, final limits monitoring and ETSL, LIMAX2CP also monitors the door zones (pre-opening, re-levelling) and unintended car movement (UCM). In addition, it is the only sensor on the market certified according to the current standards EN 81-50 and EN 61508 that in addition features inspection and start-up functions according to EN 81-20, 21 and EN 81-50. A test is also integrated to check unintended bridging of the car and landing doors at each stop.

In general, LIMAX2CP can be connected to electronic safety gear. In this case, the governor is eliminated, thus further reducing the number of components in the shaft.

Since these safety functions are integrated in the sensor, no additional safety box needs to be installed. Easy mounting is guaranteed by the cables being directly inserted on the sensor. The covers for the cables are designed in various IP protective classes (IP43, IP54 or IP65) to ensure the sensor can be flexibly adjusted to the circumstances of the lift system.

Complete safety mechanism is electronically designed

Another special feature, which to date is unique on the market, is that all safety mechanisms in the new LIMAX2CP are electronic in design. Since electromechanical switches are no longer used, the sensor is not only especially sturdy vis-a-vis vibrations and environmental influences, but also permits self-diagnosis of the sensor during operation without interrupting lift operation.

Thanks to the safety relays being eliminated and an internal energy saving switch, the LIMAX2CP enjoys low power consumption and as a result contributes to improving/preserving the efficiency class of the lift.

Safety functions can be adjusted flexibly on the spot on the lift

Two special aspects in the lift have to be taken into account, apart from the safety functions. These are on the one hand the process for traceability and the parameter assignment of the safety-relevant functions. Adjusting the safety functions on the spot to the lift system should be as flexible as possible. The configuration process of the LIMAX2CP offers an especially flexible and elegant approach.

For example, it must be ensured that short-term changes to the safety parameters are possible as part of a protected process. A shaft head can change quickly during the construction phase. The configuration of lifts no longer occurs months before construction approval, but usually at short notice. In addition, reliable reprogramming of the correct lift parameters into the sensor must be guaranteed in the event of components being exchanged.

These market requirements were taken into account during the development of the LIMAX2CP. Treotham allows customers to acquire the LIMAX2CP unprogrammed. Since no parameters are yet programmed in this condition, only a storage location is occupied. All of the later options for safety parameters for possible lifts are then configured when the sensor is to be used.

As a result, three options for programming the safety parameters are available:
• By ELGO: in this case, the parameter set must be stated when ordering.
• By the customer: programming occurs before delivery of the sensor via programming tool.
• At the lift: programming directly at the construction site using CANopen.

All three processes are protected via the configuration process. The parameter sets are created by the customer in the ELGO intranet and are protected by 32-bit CRC against incorrect entries. To activate the sensor, the fitter only has to enter the CRC code for verification stated on the sensor in the control, which activates the sensor.

The safety parameters remain in the lift data. As a result, a new sensor can be reprogrammed as required for the lift. This can also be performed directly by the controller in the lift. The documents needed for this are included in the lift documentation.

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