Security. Apart from reducing costs and generating profits, it is one of the most important aspects of the functioning of any company. Extremely stringent standards leave no illusions in this matter and quite clearly define the rules to be followed.
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In the case of industrial production, one of the key aspects of safety systems are special emergency stops that allow the machine to be stopped in the event of a threat to the life of the employee or a failure. Depending on the specific technological line and production characteristics, various options for emergency fuses are used. However, each time their use should comply with applicable law.
ANTICIPATION
- The regulations regarding safety switches are quite general - said Mariusz Lenar from the Technical Garage channel, cooperating as an expert with Automation Trader. - A lot of responsibility is placed on the designer of the machine - he added.
Of course, legal norms define a certain catalog of conditions that must be respected. This is mentioned, among others, by a special directive of the European Union, which in the case of Polish legislation was implemented by the ordinance of the Minister of Economy on essential requirements for machines of October 21, 2008.
- The regulations define, for example, the speed of stopping the machine, the fact that specific circuits must be used, how many should there be, and how densely the switches should be placed. Which part of the machine is to be turned off in case of such necessity, is a matter to be determined during the design process. So we have to anticipate all the threats we can face at this point - he said.
The most common type of emergency stop switch is the popular "mushroom" found in all sorts of machinery. These are the simplest switches, the pressing of which causes an immediate stoppage of operation, such as those found in the Siemens offer.
The appearance of such buttons is strictly defined and they must be clearly visible on the production line, so that there is no doubt that they should be used to emergency stop the entire process. The "mushroom" itself is red and should be embedded in the yellow cassette. - In the case of such switches, special safety circuits are used that guarantee 100% shutdown of the machine or its parts, depending on the need. As you can easily guess, in such circuits there cannot even be a possibility of an error - continued our expert.
PRESS THE „MUSHROOM”
As safety technology is constantly moving forward, the development could not ignore the safety switches as well. One such feature is the self-monitoring function. It consists in the fact that an additional contact is mounted to such a button, whose task is to monitor whether the panel elements are still in their places. Importantly, the buttons can also have other interesting features, such as emergency signal amplification, LED backlight or a special intrinsically safe design that allows you to place the device in a place that is at risk of explosion.
- Mentioned safety circuits, very briefly, have two very specific functions. They allow the machine to stop safely and then check whether it is possible to restart it. In the past, contactors played an important role here. However, these are a mechanical device that can remain short-circuited even though, for example, the voltage on a coil has been disconnected. There are many dangerous situations and that is why today special safety relays are used - said Mariusz Lenar.
It is also very important to restart the machine after pressing the safety button. There is no single rule here either. Very often one person's action is enough, but it is not a rule. - Each time you have to do some specific action to reset this emergency shutdown and make the machine start again. Sometimes it is enough to just pull out the mentioned "mushroom", but in other cases it will be necessary to perform a number of very specific activities. It can be, for example, closing a security gate, stopping the operator in a specific place, which is then detected by sensors, or finally holding a given button by several employees at the same time, so that at different sections of the machine everyone knows that it will be activated in a moment.
The safety button may seem like a fairly simple and not very complicated device, but it is only an apparent impression that can be obtained from the very appearance of such a button and its very specific operation. However, its importance for the entire production process and the sense of employee safety cannot be overestimated.
