New safety module for sensorless standstill detection of drive systems
26 March 2021
If a machine or system is expected to produce potentially hazardous overtravel movements, a combination of safety interlock on the guard and standstill monitor in the switch cabinet can provide the requisite level of safety. The SSW303HV is the Schmersal Group's latest sensorless standstill monitor, offering a significant improvement over its AZR and FWS series predecessors.
A key development goal was universal application of the new standstill monitor, which in total replaces fourteen variants of the previous product range. This is made possible thanks to use of a wide-range power supply for all common AC and DC operating voltages, from 24 V/DC / 24 V/AC to 230 V/AC. The increased temperature range of -25 to +55°C also opens up additional application potential.
A further benefit is its compact design – the SSW303HV takes up just 45 mm of structural width in the switch cabinet. The pluggable, coded connecting terminals ensure rapid, error-free installation, while an additional signalling contact provides information on the error status of the module.
As the standstill monitor operates entirely without sensors, the machine builder no longer needs to intervene with the ‘hardware’ of the surrounding structure. The safety module is connected directly to a three-phase motor and directly measures the frequency of the induced voltage, at rated motor voltages of up to 690 V. The safety contacts for releasing the locking mechanism close as soon as the motor comes to a standstill.
The SSW303HV can be used in safety circuits up to category 4/Performance Level e in accordance with EN 13849-1 and SIL 3 in accordance with EN IEC 61508, with all typical safety interlock designs from applicable manufacturers.