Safety Function

The module monitors the rotation speed of a turbine, independently of the HIMax overall system

and the user program. The module trips the turbine via the digital outputs .

Depending on the measuring input, the module determines the rotation speed and direction of a

sensor (pulse generator) with safety-related accuracy. To determine the rotation speed, one

turbine is equipped with three sensors. The rotation speed values calculated for the three

sensors are used for a 2oo3 evaluation and thus for calculating the rotation speed of the

turbine.

The module performs a 2oo3 evaluation of the digital input signals and provides the result to the

safety-related processor system and the user program.

The module ensures the outputs’ safety function using three switches connected in series for

each channel. This ensures that each output is two-fault-tolerant with respect to the switch.

Each switch of a channel can be individually switched off either via the system bus (I/O bus) or

via the second independent shutdown function (watchdog).

The safety function is performed for the inputs and outputs in accordance with SIL 3. with the

exception of the relay output, which is processed as a potential-free signaling contact

(changeover).