Non-Contact Safety Switches CES - EUCHNER GmbH + Co. KG - #4

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General Subject to technical modifications; no responsibility is accepted for the accuracy of this information. The advantages of the CES system at a glance Uniquely coded actuator Maximum protection against tampering The actuator can be rotated within the read head's operating distance. Can be used in harsh environment Dirt on the surface does not reduce the switching distance Precise door guides are not required General Information According to EN 1088, interlocking devices are mechanical or electrical devices which are designed to prevent the operation of a machine element for as long as the movable safety guard is left open. Non-contact safety switches and safety systems CES are interlocking devices which are designed to protect people and machines. Compared with electromechanical safety switches, they are used if: a high level of protection against tampering must be achieved extremely hygienic environmental conditions are required (e.g. in the food industry), a precise door guide is not possible, machine doors are subjected to heavy vibration. a high category according to EN ISO 138491 is stipulated during the risk analysis The CES transponder technology The non-contact safety systems described here operate on the basis of a uniquely electronically coded actuator (transponder). The name transponder is a combination of the two terms transmitter and responder. The function of a transponder is easily explained: the transponder (actuator) receives and processes the electromagnetic field from a transceiver (read head), and the data signals are then sent back to the read head (evaluation unit) as a response depending on the transponder coding. Power is supplied and data transmitted to the coded actuator by induction using a read head. The major advantage of the system is that the actuator does not contain any batteries and is therefore maintenance-free giving the user many years of service-free operation. The best known application for transponder technology is, for instance, the electronic immobilizer in automotive applications. ƒô ƒô ƒô ƒô ƒô ƒô ƒô ƒô ƒô ƒô ƒô The CES system The Coded Electronic Safety system CES comprises three components: Coded actuator Read head Evaluation unit In some systems, the read head and evaluation unit form a sealed unit, in this case the term safety switch is used, as all safety functions are integrated into one component (see section on safety switches further down). The system then consists of the components: Coded actuator Safety switch (read head with integrated evaluation) Coded actuators Each actuator supplied has a unique code and is therefore a unique element. The code in an actuator cannot be reprogrammed. Read heads The read head is fastened to the fixed part of the safety guard and is connected to the evaluation unit via a two-core screened cable. The actuator fastened to the safety guard is moved towards the read head by closing the door. When the switch-on distance is reached, power is supplied to the actuator via the read head and the read head transfers the actuator's data to the evaluation unit. Actuator and read head have a wide operating distance and a broad hysteresis. Misalignment of the door will therefore not result in the system switching off unintentionally. If the actuator is positioned exactly at the limit of the switch-on distance, vibration at the safety guard will not cause the machine to stop unintentionally. EUCHNER provides read heads in a very wide range of designs with and without guard locking (see next section). Read heads with guard locking Guard locking is a feature that prevents the unintentional opening of a door as long as there is a hazard. For this purpose, EUCHNER has read heads with guard locking in its range. They function like any other CES read head, but also contain a guard locking mechanism. Depending on the read head series and the evaluation unit used, varying levels of safety can be achieved. You will find exact information on the level of safety that can be achieved in the combinations tables for each product. Evaluation units The read head is connected to a special CES evaluation unit. This unit checks the actuator's bit pattern. The data transmission from the read head to the evaluation unit is dynamic and single-channel. All potential faults (e.g. broken cable, short circuit, failure of the actuator) are reliably detected. The number of read heads that can be connected depends on the evaluation unit. The evaluation units have enable paths with which e. g. relays or contactors can be switched. If the evaluation unit detects a valid actuator, the evaluation unit closes its enable paths. How the evaluation is performed in detail depends on whether the evaluation unit is a unicode or multicode evaluation unit. ƒô ƒô ƒô ƒô ƒô