Measurement electronics SIL3 | PL e

Measurement Electronics SIL3 | PL e — Dual-Channel Redundancy

The highest safety level available here: The measuring amplifier applies a bridge signal to two galvanically isolated current outputs; a safety controller compares them and switches the system to a safe state in the event of a deviation. Redundancy is achieved through the two channels, not through higher measurement accuracy — these devices are safety components, not measuring instruments.

This always involves two parts: the amplifier and the controller that checks its channels. Without a safety controller, the redundancy remains unused. If you want to manage without a controller, you can find the alternative under SIL1 | PL c — where the protective function is integrated into the device.

The Devices

• SMM-DR — Amplifier in a DIN rail housing for the control cabinet. The measuring chain can be tested during operation via the test input: a 24 VDC pulse increases the current of channel B by 1 mA. If the channels deviate from each other by more than 10%, the controller switches the system to a safe state.
• SMM-HD — The same amplifier in an IP65 field housing for mounting outside the control cabinet. One or two amplifiers are located in the same housing; two measuring points are monitored independently with two bridges.
• SCU-DR — The corresponding programmable safety controller. Freely programmable with up to 800 AWL (STL) instructions, function plan-oriented, with cross-circuit detection and external contact monitoring. For connection to the plant control system, PROFISAFE and FSoE up to SIL3 or PL e are available in addition to interface modules.

What belongs to it

The matching transducers can be found under load cells & force transducers, the rest of the range under Measurement Electronics. Architecture, key figures for system certification, and typical applications are explained on the page Functional Safety SIL | PL.