To meet the needs of specialist manufacturers that retrofit electrical equipment to vehicles, Pilz has introduced Type-Approved (or 'e-marked') safety relays. One of the first users of these is Terberg Matec UK, a leading builder of vehicle bodies for the kerbside collection of domestic recyclable waste.
The new e-marked PNOZ X2C and PNOZ X2.1C relays have Type-Approval in accordance with Directive 72/245/EEC, Radio interference (electromagnetic compatibility) of vehicles (as last amended by Directive 95/54/EC, Automotive Electromagnetic Compatibility), which enables them to be used on vehicles placed on the market in the EU without any further testing. These relays will typically be used to monitor emergency stop switches, guard switches and limit switches on dustbin lorries, road sweepers, mobile access platforms (cherry pickers), vehicle-mounted hoists and similar applications.
Currently there is a transition period until the use of e-marked electrical equipment becomes mandatory. Meanwhile, the Pilz PNOZ X2C and X2.1C are believed to be the only e-marked safety relays available, developed directly in response to requests from customers.
Broadly similar to the existing PNOZ X2 and X2.1 safety relays, the new models feature two normally-open safety contact outputs and are suitable for use in applications meeting the requirements of EN 954-1 Category 2 or 4. While the PNOZ X2C has a monitored manual reset, the PNOZ X2.1C can be configured by the customer to have either a manual reset or an automatic reset, depending on the requirements of the application.
Prior to the PNOZ X2C being available, Terberg Matec UK had been using a conventional electro-mechanical safety relay from Pilz. However, space on the vehicles is at such a premium that the relay had to be mounted sideways in the electrical cabinet, making it impossible to view the status LEDs. While the company's main aim was to find a more compact safety relay, it also wanted to be prepared for the time when the use of e-marked electrical equipment became mandatory. It was therefore doubly pleased with the Pilz PNOZ X2C relay that is both compact and e-marked.
All multi-compartment vehicle body systems built by Terberg Matec UK have a safety relay to monitor emergency stop switches. While the Kerbsider model has three of these, the Toploader can have up to seven, all wired in series. The two output circuits from the relay switch the common feed to the PLC and the power to the solenoids on the hydraulic valves.
Stocks of PNOZ X2C safety relays are held by Terberg Matec's local electrical distributor, BPX, and additional stocks are maintained by Pilz as a back-up. Gary Ashley, Regional Manager at BPX, comments: "Pilz is the only supplier of safety relays that we deal with and the company was very helpful in sourcing this specialist product to meet Terberg Matec's requirements. Now that Pilz has introduced a range of high-quality, non-contact safety switches, it is likely that we will soon be supplying some of these to Terberg Matec as well."
A spokesman from the engineering department at Terberg Matec comments: "We have been very pleased with the Pilz relays, which have proved to be extremely reliable. The Pilz relay has been incorporated in our circuits providing the functionality that enables the detection of both activation and deactivation of emergency stop buttons and system faults, tripping out exactly as it is designed to do. The service we have had from both BPX and Pilz has always been good, and we would have no hesitation in recommending either company as a supplier."
It is likely that, as the end of the transition period draws closer, more niche-market automotive manufacturers will find that they need to install e-marked safety relays in order to comply with current Directives. Pilz believes that demand for its compact PNOZ X2C and X2.1C products will increase, and Terberg Matec has clearly demonstrated that these safety relays operate reliably within the harsh environments encountered on heavy vehicles.