For applications requiring ten or more safety contacts, Pilz Australia has launched two new expansion modules, PNOZ s7.1 and PNOZ s7.2, for use with its slimline PNOZsigma relays. These two new modules enable the number of contacts to be expanded considerably, thereby offering the potential for considerable savings in space compared with traditional safety relays.
The PNOZ s7.1 of this PNOZsigma range features three normally-open safety contacts. It is connected by means of a simple plug to a PNOZsigma base unit safety relay type PNOZ s1, s2, s3, s4, s5, s6 or s6.1. In addition, the PNOZ s7.1 incorporates a separate feedback loop that enables the 17.5mm wide module to be used as a standalone safety relay.
When a PNOZ s7.1 is used either as a standalone unit or with a PNOZsigma base unit, further expansion is possible by connecting a maximum of ten PNOZ s7.2 modules, each having four normally-open safety contacts and one normally-closed auxiliary contact. Alternatively, a PNOZ s7.2 can be connected to a base unit as a single expansion module. As with the PNOZ s7.1, the PNOZ s7.2 measures 17.5mm wide.
For applications requiring an even more number of contacts, multiple PNOZ s7.1 modules can be used, each with a maximum of ten PNOZ s7.2 modules. The only additional requirement is that a 24V supply must be provided for each PNOZ s7.1 module. Although there is theoretically no limit to the number of PNOZ s7.1 expansion modules that can be used, each one adds 20ms to the 50ms reaction time of the base unit. Care must therefore be taken to ensure the total reaction time remains acceptable.
Industries where the PNOZ s7.1 and PNOZ s7.2 modules are expected to be particularly useful are automotive and paper. However, they are equally suitable for other industries where ten contacts or more are required.