When is Safe Safe Enough?
In designing safe electrical products, the manufacturer addresses the protection against the potential hazards from electric shock, fire and mechanical aspects of the product in operation as intended, and sometimes even when used not as intended. The guidance they use in this effort comes from a significant array of standards and other documentation, developed by one or more of the standardization organizations or sometimes the manufacturer themselves. Overall, these electrical products have a pretty good record given the millions and millions of devices being used on a day-to-day basis.
However, there are some critical where electrical devices are specifically used to ensure safe operation of a system - such as those used with metal-working machinery to prevent accidents to operating personnel, and perhaps in control of elevators to ensure that the passengers are not subjected to a plummeting cab that becomes out of control. Within the standards development world is an organization called the IEC - International Electrotechnical Commission - which has published a series of standards identified as IEC 61508 "Functional safety of electrical/electronic/programmable electronic safety-related systems". This series of standards provides the framework and specific instructions for the design, development, production and end-of-life considerations that can be applied to systems, and that can be used to develop specific product requirements for electrical equipment used within these safety systems. Product Functional Safety standards have been developed for: Electrical equipment for measurement, control and laboratory use; Electro-sensitive protective equipment; Functional safety fieldbuses; Adjustable speed electrical power drive systems; and, in draft, Programmable Controllers. Other standards apply to functional safety considerations and other product standards are under development.
This effort imposes additional requirements on the manufacturers, but considering the consequences of the safety equipment not functioning correctly the extra effort is definitely warranted. If you have an interest in this area of safety practices, please contact Ken Gettman at firstname.lastname@example.org.
04-08-2009 2:31 PM