Switchgear overview

8,2 kOhm Monitoring resistor Safety contact edgeEvaluation electronics Safety switchgear are used in conjunction with safety contact elements wherever the secureprotection of individuals and equipment is required. The safety switchgear presented here employ the quiescent current principle for monitoring the safety contact elements as this meets the high demands for fault recognition and safety. The safety level provided is at- tested to by approvals from the BG and TÜV for use up to safety category 3 in accordance with EN 954-1.To monitor the quiescent current, a monitoring resistor is mounted at the end of the signal transmitter line. If the setpoint quiescent current is flowing, the output relays are activated and the switching contacts are closed. If the switching element is activated or the safety circuit is interrupted, the relay switch contacts open. The relay switch states and the applied operating voltage are indicated by LEDs.

Safety Considerations

The following risk chart reproduced from EN 954-1 offers instructions for selecting thesafety system category. The selection of the appropriate safety combination and its safety level is the responsibility of the design or construction engineer. The instructions shown do not release the design or construction engineer from the obligation to observe all relevant standards in the design of the safety equipment.

KategorieB1234

S Degree of injury S1Light (generally reversible) injuriesS2Severe (generally irreversible) injuries F Frequency and/or duration of the hazard F1Seldom to frequentlyF2Frequent to continuous P Opportunity to avoid the hazard P1Possible under certain conditionsP2nearly impossible

P2P1P2P1F2F1S2S1

Category selection B, 1 - 4 categories for controller components relevant to safetyPreferred category for reference points Possible category requiring additional measuresExcessive measure in view of the hazard