IS rotary speed monitor `does the work of two`

Turck Banner claims to be offering the first rotational speed monitor with IS (intrinsically safe) inputs and both analogue and relay outputs. The company asserts that the device, which monitors pulse sequences from Namur sensors in hazardous areas and converts them to a 4-20mA output, as well as indicating under- or over-speeds, replaces two conventional devices at less than half the price.

An LCD readout on the front panel of the Multimodul MK21-R1 indicates the actual speed of rotating objects such as shafts and gears. Up to 1kHz, it operates on a digital pulse principle. For higher speeds, the output relay is energised if the rotational speed falls outside a preset "window".

The device is set up using prompts shown on the LCD. It can be programmed to monitor the input circuit for wire breaks or short circuits. To prevent under-speeds from being reported during start-up, a time delay of up to 1,000s can be set.