Your questions are far to general for it to be possible to give specific answers, but assuming that you are concerned with a product for the EU (i.e. which needs CE marking), the following may be of some assistance.
- If your product is covered by the Machinery Directive, then E-stops are mandatory except in certain specific circumstances which are given in the Directive. - Even if your product is not within the scope of the Machinery Directive, read section 1.2.4 of the annex 1 to the Directive and this will help answer several of your questions (there is a link to the full text of the directive, including Annex 1, here: http://www.conformance.co.uk/ce_marking/ce_list.html. - LVD standards do not, in general, mandate the use of E-stops. - Refer also to EN 418 "Safety of machinery. Emergency stop equipment, functional aspects. Principles for design" - EN 60204-1, the standard for electrical safety of machinery, does not currently permit software to be used for emergency stop functions, but this standard was introduced before the current generation of 'safety PLC's' was common. You certainly should not use an ordinary desktop PC or PLC for safety related control functions, including E-stops. EN 62061 provides guidance on the use of programmable controllers in safety related machinery control applications. - You should also be familiar with the basic principles of redundancy and monitoring which are established in EN 954-1 if you are going to attempt to design a control system which relies on any kind of programmable logic for safety. - There are standards for the actual actuators as well, e.g. EN 60947-5-5. If you want more advice, please contact me directly. Regards Nick. At 9:54 am -0800 26/1/06, Joel Sandberg wrote: > To List Members; > >I would appreciate guidance on the subject of emergency stop >switches (buttons). > >When (if every) is an emegency stop switch manditory? > >Must an emegency stop switch be a hardware only function, or can it >operate through the machine's computer and software? > >Does the emergency stop switch have to turn off power to the >machine, or can it just stop the offending action, while leaving >power on? > >What sort of responce time should be expected for an emergency stop >switch (2 part question): >a) How long (realy how short a time) must the operator hold >emergency stop switch in order for it to operate (i.e when I want to >hit the button and run, how long to I need to stand there and hold >the button before it functins)? >b) How long can the machine continue to move/run/function after the >switch is pressed? > >Thank you. > >J. Sandberg - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
