Emergency switch
The emergency stop switch , and emergency stop switches written or emergency stop called, is a switch to machines, vehicles and equipment. It is used to quickly put them in a safe state in the event of danger or to avert danger. Different strategies are pursued depending on the field of application; in the simplest case, triggering is followed by an interruption of the power supply.
construction
Emergency stop switches on machines have a red actuating element on a yellow background. Mushroom-shaped switches are a common design . B. also pull cord switch (pull cord switch) and safety light barriers .
function
The emergency stop switch must lock after actuation and, depending on the security level to be achieved, can only be returned to its original position with a key, by turning the emergency stop switch or pulling it out. It must be designed in such a way that the machine or system operator can operate it immediately in an emergency.
Normally, together with emergency stop switches, emergency stop switching devices are used that meet the necessary reliability requirements, for example the machine must not restart by itself after unlocking. Emergency stop circuits are divided into stop categories depending on the technical conditions ( EN ISO 13850 : 2008 point 4.1.4 and EN 60204-1 : 2006 point 9.2.2):
- Stop categories
- Stop category 0: Energy supply to the drive elements is cut off immediately (only useful if the sudden switch-off of the energy does not cause any danger)
- Stop category 1: controlled stopping: the machine is put into a safe state, only then is the energy to the drive elements finally separated. This is useful if clamps, brakes, etc. Need energy.
- Stop category 2: The machine is put into a safe state, but the energy is not disconnected. This category should only be used if there is no technical possibility to safely separate the energy. For example, on a crane with a lifting magnet, switching off the voltage on the magnet would cause the load to crash (only EN 60204-1: 2006, point 9.2.2).
Security aspects
With regard to the hazards, safety considerations and possible effects in the event of a failure of a safety device such as the emergency stop circuit must be carried out. Use is z. B. EN ISO 13849 or safety requirement levels according to DIN EN 61508 or the international standard IEC 61508 . Here are risk graphs created to quantify the risks. This results in five safety categories. The higher the risk, the higher the requirements for the fail-safe safety of the shutdown device.
- example
- If z. If, for example, category 3 is determined from the risk graph, a redundancy is required that maintains the shutdown function in the event of a single fault and makes this fault recognizable, for example by preventing the system from being switched on again. This means that not only must all components and line connections be duplicated, but also that the duplicate components are monitored individually. Coupling relays and contactors monitored by additional contacts are used, which have to be distinguished by the fact that their contact blades are positively guided: If a NO contact remains stuck due to contact welding, all other contact blades no longer move - an NC contact used for monitoring then closes when the coil is de-energized not and prevents switching on again (the normally closed contact is in the switch-on circuit).
In principle, the closed- circuit principle is used; d. H. if the auxiliary power fails, the safe state is achieved. Technical specifications are contained in DIN EN 13850 (successor standard to DIN EN 418). There is no hard specification for a label.
In the event of an emergency stop, the system must be de -energized to protect against electric shock . Safety standards mention the emergency stop. In the event of an emergency stop, it is not required that the entire machine is de-energized. A drive must be able to be stopped when a dangerous situation is recognized by the operator to protect against a hazard . Voltage is required for controlled braking of the drive. In most cases, e.g. B. a programmable logic controller (PLC) or connected PC technology is not switched off. Brakes, cooling, suction, etc. The safety technology is usually not switched off as long as it does not pose a hazard.
If several components, each with an emergency stop switch, work together on a system, each of these buttons must shut down the entire system. For example, a laser processing machine must be able to be switched off both by the prescribed emergency stop button of the laser and by that of the machine.
DIN-VDE standards on the subject of emergency stop devices
The following DIN standards are among the most important for electrical safety and explain the term emergency stop:
| VDE 0113 | Part 1 2007-06 DIN EN 60204-1 | Safety of machines - Electrical equipment of machines - Part 1: General requirements (IEC 60204-1: 2005, modified) German version EN 60204-1: 2006 |
| VDE 0660 | Part 210 2017-08 DIN EN 60947-5-5 | Low-voltage switchgear - Part 5-5: Control devices and switching elements - Electrical emergency stop device with mechanical latching function (IEC 60947-5-5: 1997 + A1: 2005 + A2: 2016) German version EN 60947-5-5: 1997 + A1 : 2005 + A11: 2013 + A2: 2017 |
Other standards:
| VDE 0100 | Part 460 2002-08 DIN VDE 0100-460 | Erection of low-voltage systems - Part 4: Protective measures Chapter 46: Disconnecting and switching (IEC 60364-4-46: 1981, modified) German version HD 384.4.46 S2: 2001 |
This standard replaced DIN VDE 0100-460 (VDE 0100 Part 460): 1994-02. The term “emergency shutdown” including “emergency stop” has been changed to “actions in an emergency”. An informative Appendix ZA explains what is meant by “actions in an emergency”.
A concept is being discussed in Europe to standardize the use of terms related to "emergencies". These are compiled in the appendix and are intended to make the terms easier for the user to understand. The following four terms are involved: stopping in an emergency (previously emergency stop), starting up in an emergency, switching off in an emergency (previously emergency switching off) and switching on in an emergency.
DIN EN 418 (safety of machines, EMERGENCY STOP devices, functional aspects, design principles) has been replaced by DIN EN ISO 13850 (safety of machines - emergency stop function - design principles). Please note the correction of the term emergency stop in emergency stop (translation error in the English word emergency stop has been corrected).
According to EN ISO 13850, every machine (exception: manually portable and hand-guided machines) must be able to be shut down by a single action by any person present without long deliberations. This is achieved with the emergency stop function.
Problem of terminology
In German usage, the two functions emergency stop (= switching off, interruption of the energy supply) and emergency stop (= stopping, shutting down the moving machine parts) are often subsumed under the term "emergency stop", which is sometimes possible - even among experts Confusion leads. It is correct to use “Not-Aus” as the German equivalent of the English term emergency switching off . However, there were German standard editions which also wrongly reproduced the English term emergency stop with the expression "Not-Aus". This was done in particular by EN418 (safety of machines; EMERGENCY STOP device, functional aspects; design principles; German version EN 418: 1992) and in some cases also the old EC machinery directive 98/37 / EC .
The successor standard ISO 13850 has corrected this and speaks of an emergency stop . In the new version of the Machinery Directive (2006/42 / EC or 2009/127 / EC), the incorrectly used term was also replaced by emergency stop .
Automatic and manual main switches on vehicles
In vehicles such. B. in racing cars or commercial vehicles , the emergency stop switch ( battery disconnect switch ) interrupts the ignition and, if necessary, the fuel supply as well. In some cases the vehicle is completely de-energized (risk of short circuit and fire in the event of an accident). Modern cars have automatic disconnection, which is activated at the same time as the airbag is deployed and disconnects the main circuit from the battery. Other electrical systems such as hazard warning lights , car phones, etc. a. remain functional via a separate circuit for safety reasons.
On motorcycles , a battery disconnect switch or "kill switch" is usually attached to the right steering wheel switch. Motorcycles with electronic fuel injection (from January 1, 2006, Euro 3) have an automatic battery cut-off switch (position sensor) that is triggered when the vehicle is tilted at an angle that indicates a fall. The ignition of motorcycles must also be switched off if the side or main stand is folded out and a gear is engaged at the same time.
software
In analogy to physical emergency stop switches, there are also emergency stop mechanisms in software . These can be used, for example, by manufacturers to deactivate software or by owners to deactivate stolen devices.
Some malware includes emergency stop - as for example in the cyberattack of WannaCry - Ransomware was the case in May 2017th
There is also a debate about implementing kill switches in robots and advanced artificial intelligence systems .
literature
- Patrick Gehlen: Functional safety of machines and systems. Implementation of the European Machinery Directive in practice. 2nd Edition. Publicis Corporate Publishing 2010, ISBN 978-3-89578-366-1
- Alfred Hösl, Roland Ayx, Hans Werner Busch: The electrical installation in accordance with regulations, residential construction, commercial industry. 18th edition. Hüthig Verlag, Heidelberg 2003, ISBN 3-7785-2909-9
- Günter Boy, Horst Flachmann, Otto Mai: The master's examination in electrical machines and control technology. 4th edition. Vogel Buchverlag, Würzburg 1983, ISBN 3-8023-0725-9
Web links
Individual evidence
- ↑ Emergency stop: EN 13850 . In: WEKA MEDIA - The specialist publisher for your professional success . February 27, 2015 ( weka.de [accessed March 19, 2018]).
- ↑ Patrick Gehlen: Functional safety of machines and systems. Implementation of the European Machinery Directive in practice . 1st edition. Publicis Corporate Publishing, ISBN 978-3-89578-281-7 , p. 24
- ↑ Pyrotechnic safety switch PSS. (PDF) Autoliv , archived from the original on February 27, 2014 ; accessed on February 27, 2014 .
- ↑ Chris Davies: Microsoft remote software “kill switch” confirmed . September 19, 2009.
- ^ Martyn Williams: 10 things to know about the smartphone kill switch . June 24, 2014.
- ^ Sewell Chan, Mark Scott: Cyberattack's Impact Could Worsen in 'Second Wave' of Ransomware . The New York Times. May 14, 2017. Retrieved May 14, 2017.
- ↑ Warning: Blockbuster 'WannaCry' malware could just be getting started ( en ) NBC News. Retrieved May 14, 2017.
- ↑ Ivana Kottasova: Europe calls for mandatory 'kill switches' on robots . CNNMoney. January 12, 2017. Retrieved May 14, 2017.
- ↑ Selena Larson: Killing the immortal: Why scientists are debating the life span of robots . CNNMoney. January 26, 2017. Retrieved May 14, 2017.