Weidmuller – SIL3 safety relay ensures functional safety with reliable and safe shutdown (SCS 24V DC SIL3)

Weidmuller’s new SIL3 safety relay ensures functional safety with reliable and safe shutdown of process industry plants and plant components in the event of an emergency.

The SCS 24V DC SIL3 safety relay is designed to ‘guarantee’ emergency shutdown of systems and system components operating in the process industry. TUV NORD has certified that the safety relay fulfils the Safety Integrity Level specifications in accordance with EN 61508.

Safety shutdown is of critical in the process industry because it serves functional safety, for instance in backup systems with high DC voltages. EN 61508 specifies that all devices used in safety circuits must fulfil particularly strict conditions. SIL (Safety Integrity Level) makes it possible to classify corresponding devices according to the reliability of their safety function and the safety-oriented design principles that must be maintained in order to minimise the risk of malfunctions, says the company.

A special circuit arrangement makes the input circuit immune to test pulses, which are usually used in distributed control systems (DCS) to monitor the status of ns or, to be more precise, signal circuits. The maximum permissible switching voltage is 250VAC/30VDC and the maximum permissible switching current is limited to 5A. A standard internal fuse provides short-circuit protection. The typical break time is about 14ms and the make time 7ms. The input of the safety circuit of the SCS 24V DC SIL3 safety relay has a rated control voltage of 24VDC (+/-20%) and 35mA current consumption. To ensure rapid on-site replacement, the fuse is easily accessible.

The design of the monitoring circuit is compelling and has a wide voltage input from 24 V AC/DC to 230 V AC/DC which forms the basis for individual application solutions.

The safety relay is designed for use in a wide range of temperatures from -25C to +50C without restrictions. Due to its compact dimensions of just 113.6mm x 22.5mm x 117.2mm (length/width/height) the SAFESERIES safety relay requires just a small amount of space on DIN TS 35 mounting rails, says the company.