Contactless coded safety switch
May 2017, Operator Interfaces, Switches & Relays
Interlocking devices are solutions used to protect operators from dangerous machinery. As such, they represent an important and fundamental element of the machine and should be integrated during the early stages of the machine design.
Comitronic-BTI markets many tamper-proof coded safety switches using the Actom3 process, which is based on electronic monitoring and internal relays thus negating the need for a separate safety module. This solution is not only cost effective (as the external relay is not needed), but also simplifies electrical wiring and saves space in the panel. The high switching capacity of both safety circuits (2 A/48 V) is sufficient for most machines in industries such as packaging, palletising, woodworking, robotics, food industry and many more. VigilGuard interlocking devices integrate the Actom3 process and as such benefit from this proven technology.
In the machine safety market, traditional mechanical interlocking devices require the alignment to be exact and often have a short life expectancy due to the breakage of the keys. Another disadvantage of the traditional mechanical interlocks is that the actuating holes on the devices themselves do not comply with the demanding standards of the food industry, as bacteria can accumulate in the holes.
The VigilGuard coded contactless solution solves the challenges of the traditional interlock: when energised, the coded bolt is activated and inserted into the coded strike head. The solution then guarantees that the door is closed and locked correctly by reading the code in the strike head, thereby confirming that the bolt is inserted into the correct strike head before actuating the safety contacts. Due to the dead bolt design, there is no mechanical wear and the mechanical lifetime expectancy is over 10 000 000 cycles. The housing material, Zamak (zinc-aluminium-magnesium-copper) is highly resistant to harsh environments and the rough handling experienced on heavy doors, which are commonly used in the automotive and steel industries. The smooth and hygienic design simplifies the cleaning process, as there is no cavity in the switch and the strike head has a central hole to release any water.
Fitted with internal relays, VigilGuard achieves the highest safety level (PL4e according to ISO EN 13849-1, or Category 4 as per EN954-1), without having to be wired to a safety module. The redundancy of the safety lines, self checking circuitry, inclusion of a manual reset and emergency manual unlocking system allows it to be totally independent and safe.
To ensure that the device is easy to wire, the redundant safety lines have a potential free switching capacity of 2 A/48 V, allowing them to be connected directly to most machines’ contactors. The optional dual M12 connectors make wiring devices in series easy, while maintaining the same safety level.
Three LEDs give operators an overview of the state of the switch:
• Power On/Door Unlocked – when the power supply is not in the correct range, or when the temperature of the device becomes abnormal, a visual indication is given via the LED and the machine is automatically switched into a safe state.
• Door locked.
• Eco mode/standby.
For more information contact Brandon Topham, RET Automation, +27 (0)11 453 2468, email@example.com, www.retautomation.com