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In signal and control circuits that can operate with low currents and voltages, the intrinsic safety approach simplifies circuits and reduces installation cost over other protection methods. Areas with dangerous concentrations of flammable gases or dust are found in applications such as petrochemical refineries and mines.
Equipment can be designed or modified for safe operation in hazardous locations. The two general approaches are: Intrinsic safety Intrinsic safety, also called non-incendive, limits the energy present in a system, such that it is insufficient to ignite a hazardous atmosphere under any conditions. This includes both low power levels, and low ...
Once a conceptual design is completed, the other safety strategies should be applied along with the inherently safer design concept. However, in this case, the project cost would significantly increase to have the same risk level at the same reliability relative to if ISD (inherently safer design) was adopted during the conceptual design stage.
The international standard IEC 60446 Basic and safety principles for man-machine interface, marking and identification - Identification of equipment terminals, conductor terminations and conductors was a standard published by the International Electrotechnical Commission (IEC) that defined basic safety principles for identifying electrical conductors by colours or numerals, for example in ...
Certification is achieved by proving the functional safety capability (FSC) of the organization, usually by assessment of its functional safety management (FSM) program, and the assessment of the design and life-cycle activities of the product to be certified, which is conducted based on specifications, design documents, test specifications and ...
Galvanic isolation is used where two or more electric circuits must communicate, but their grounds may be at different potentials. It is an effective method of breaking ground loops by preventing unwanted current from flowing between two units sharing a ground conductor. Galvanic isolation is also used for safety, preventing accidental electric ...
Ground loops can also exist within the internal circuits of electronic equipment, as design flaws. Addition of signal interconnection cables to a system where equipment enclosures are already required to be bonded to ground can create ground loops. Proper design of such a system will satisfy both safety grounding requirements and signal integrity.
For a device that makes use of the secondary breakdown effect see Avalanche transistor. Secondary breakdown is a failure mode in bipolar power transistors. In a power transistor with a large junction area, under certain conditions of current and voltage, the current concentrates in a small spot of the base-emitter junction.