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The safety barriers ensure that, in normal operation, and with the application of faults according to the equipment protection level (EPL), even if accidental contact occurs between the instrument circuit and other power sources, no more than the approved voltage and current enters the hazardous area.
The barrier in the isolator allows 350 mA to be run through the segment up to the Spur/junction Box through trunk cable. Since infallible resistors are used, devices from Zone 0/1 or 2 can be direct connected. Having 350 mA, now allows users to power up to 16 Fieldbus devices (20 mA each) at 500 m while retaining intrinsic safety.
Unlike ATEX which uses numbers to define the safety "Category" of equipment (namely 1, 2, and 3), the IEC continued to utilise the method used for defining the safe levels of intrinsic safety namely "a" for zone 0, "b" for zone 1 and "c" for zone 2 and apply this Equipment Level of Protection to all equipment for use in hazardous areas since ...
An output signal switching device (OSSD) is an electronic device used as part of the safety system of a machine. It provides a coded signal which, when interrupted due to a safety event, signals the machine to shut down. It works by converting the standard direct current supply, usually 24 volts, into two pulsed and out-of-phase signals.
Amplifiers with an isolation barrier allow the front-end of the amplifier to float with respect to common mode voltage to the limit of the barrier's breakdown voltage, which is often 1,000 volts or more. This action protects the amplifier and the instrument connected to it, while still allowing a reasonably accurate measurement.
A safety barrier is a component which prevents passage into a dangerous area. It is commonly used to mitigate risk in the Hazard-Barrier-Target model, as studied in safety science. Work Safe Victoria (an Australian organization) defines a Safety Barrier as a device that: [1] physically separate the work area and the traveled way,
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 ...
The safety benefit of reducing the power delivered to a short circuit in the load is proportional to the operating current limit. Foldback current limiting is most likely to be found in a switch-mode power supply when it is a component in a product that is independently certified to meet regional safety standards. [2]