Marco Paglietta says....‘All safety devices should be controlled by an independent safety controller’
Marco Paglietta, Head of Marketing, ReeR Safety, elaborates upon a few important concepts of Safety Sensors.
To deliver high quality products for most of today’s industrial applications.
How long has been ReeR active on the market?
ReeR has been operating since 1959. Our 60 years of experience in the safety sensors industry allow us to deliver high quality products for most of today’s industrial applications.
Why is it important to install safety devices on a machinery?
Installing safety devices is important to guarantee the safety of operators during all phases of a manufacturing process and to keep the accident and near-accident level as low as possible.
What is the difference between a sensor and a safety sensors?
A safety sensor is a device that is engineered to provide maximum safety also when failures occurs. A safety sensor will always contribute to shut down the machine also in case of sensor failure. An ordinary sensor may fail to do so whilst leaving the machine running, this is the most critical situation for operator safety.
How is this achieved?
In order to achieve this all safety devices have a built-in redundancy circuitry that always allow safety functionality also when failure occurs. It is important to use safety devices across the whole line by connecting safety sensors to safety relays or safety controllers, guaranteeing that a safety channel is implemented across the whole line.
Are safety devices generally connected to the general process PLC of the machinery?
No, all safety devices should be controlled by an independent safety controller, like for example Mosaic. In alternative, a simpler safety relay can be used or, for bigger machineries, the use of a safety PLC is also quite standard.
What happens if I connect a safety sensor to a control PLC?
A standard control PLC does not have the capabilities of reading and interpreting feedback signals from the safety device. In an event of a failure of either the PLC or the safety device, there could be a possibility that the machine will not shut, hence jeopardising the operator’s safety.
What is the difference between Type 2 and Type 4?
The main difference is in the ability of withstanding internal failures. With a Type 2 device a single fault can result in a loss of the safety function, alternatively with a Type 4, the accumulation of up to three undetected faults does not bring to a loss of the safety function. As a result, Type 4 devices allows achieving the highest performance level PLe (Cat. 4) whilst Type 2 devices can only reach PLc (Cat. 2) levels.
Are ReeR safety sensors manufactured according to the norms?
Absolutely, all our safety sensors are manufactured according to the European Machine Directive 2006/42/EC. The CE mark has been obtained by the German TUV.
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