Reliable access guarding

A NEW safety solution from Leuze with induction loops, light curtain and monitored signal sequence satisfies the requirements of revised standard EN 415-4, thereby ensuring maximum safety.

The access area is protected by a safety light curtain. In addition, induction loops are embedded in the floor in front of and behind the safety sensor. The safety system can thereby distinguish between forklift truck and people.

Up to now, many material transfer stations with automatic restart were safeguarded as follows: electro-sensitive protective equipment (ESPE) secured the access point – if the ESPE is interrupted, the machine and conveyor are stopped. To avoid needing to restart the stopped machine after loading by a corridor supply vehicle, such as a forklift truck, two induction loops are used as muting signals. These are located in the floor in front of the ESPE. When the forklift moves over the induction loops, the electro-sensitive protective equipment is temporarily bridged. This solution no longer corresponds to the current state of safety technology: The system often ends in a single-channel evaluation logic; as a result, the safety performance is no longer adequate for the given application under certain circumstances. A new type of access guarding for a pallet magazine aims to prevent the entry of persons but simultaneously allow pallets to enter by means of a forklift truck.

Manufacturers and operating companies can now make use of a new solution that is described in the future version of standard EN 415-4. Two induction loops  are also used for this type of access guarding on pallet magazines. The difference to traditional concepts: Both of the induction loops are not located in front of the danger zone. Instead, one is located outside of the danger zone and the second is located behind the electro-sensitive protective equipment, i.e, within the danger zone. The ESPE – the optoelectronic protective device – also remains at the previous position. As before, it separates the traffic zone and danger zone. In addition, there is also a safety system that monitors a defined sequence of signals and initiates the automatic restart.

Ready-to-use system

Leuze offers the described safety solution for access guarding on pallet magazines with automatic restart as a complete package that has been tested and validated with respect to safety with the following components:

• Induction-loop set with evaluation unit
• MLC 500 safety light curtain, with device columns for floor mounting
• MSI 400 safety control, programmable and with induction loop controller • Leuze safety program
• 2-channel safety output
• Acknowledgement box as electromechanical reset apparatus

The reset apparatus is used if a sequence is not correctly completed. Or a person interrupts the electro-sensitive protective equipment. The button is used to confirm to the system that the process can be correctly restarted and that persons are no longer located in the danger zone.

As a ready-to-use system, the solution from the Sensor People at Leuze can be used immediately after installation. System owners are, thus, always on the safe side and already satisfy the requirements of the future EN 415-4 today.

For more information, visit www.leuze.com