Protection of robot cells with safety light curtains

Work safely and efficiently with switchgear in closed machines

Situation sketch

In this application example, a conveyor belt transports cartons to two robot palletizing cells. The technical installation is fully protected by a gate with three entrance gates, for every robot there is an access door and there is access to the conveyor belt. The entrance doors are equipped with a safety switch and solenoid locking switch. As soon as the gateway to a robot is opened, the robot stops. When the access door to the conveyor belt is opened, the entire machine stops.

Protection with safety light curtain

The finished pallets are picked up by a forklift truck. The access gate to the finished pallets is protected and secured by a safety light curtain. The safety light curtains prevent the machine from starting from the rest position. An incoming forklift truck is detected because the light curtain is interrupted and the robot cell stops. As soon as the truck comes out of the safety zone of the safety light curtains, the safety relay switches to a safe situation.

Access security

Not only when retrieving the completed pallets do the robots switch through the detection of the light curtains, as soon as one or more rays of the light curtains are blocked, the robot in question switches off. This can also happen, for example, once an employee passes through the protected area. The manual restart button is located near the safety light curtain. The system is equipped with four emergency pushbuttons (e-stop). Read more about light curtains with muting function.

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Conventional safety components

In order to build up the safety circuit with conventional safety components, at least 6 safety modules should be used, which must be connected to perform the required functions. 2 safety relays for the light curtains, 3 relays for the slide switches and 1 relay for the emergency stop buttons.

Solution with programmable safety relay | Mosaic:

When using the programmable safety relay Mosaic from ReeR, the following 2 modules are sufficient to install the safety circuit:

• Main module Mosaic M1
• MI8O2 expansion module

The reset buttons are not included in the diagram because they are directly connected to the feedback from the OSSD safety outputs. The 4 e-stop buttons are included in the diagram as a single block.

The programmable safety relay Mosaic - Safety PLC from ReeR Safety is easy to configure using 'drag & drop software'. With this you are able to set up your own safety system that fully meets your wishes and requirements. The software provides a clear overview of the situation, making functions easy to add.

Read more about programmable safety relay - Mosaic

Read more about application examples for machine safety with safety PLCs and safety switches. 

Application examples: 

• Speed monitoring of unsafe machines and plants
• Loading and unloading of systems

See the complete overview of application examples