Some aspects of the design of intrinsically safe circuits.

  • 23 Pages
  • 3.25 MB
  • English
Ministry of Power
SeriesResearch reports -- no.256.
The Physical Object
ID Numbers
Open LibraryOL13731155M

Displays) intrinsically will begin with an introduction to the practical side of intrinsic safety circuit design.

Start With The Field Device All intrinsically safe circuits have three components: the field device, referred to as the intrinsically safe apparatus; the energy-limiting device, also known as a barrier or intrinsically safe File Size: KB.

but to the entire intrinsically safe circuit, in accordance with EN/IEC Special significance of the Ex i isolators Intrinsically safe circuits are generally composed of the following elements: the intrinsically safe equipment, that is, a consumer installed in the Ex i area (e.g., an Ex i.

in a mixed intrinsically safe circuit with concentrated capacitances and/or concentrated inductances on condition that L i intrinsically safe circuit, the certified C o and L o values must be reduced by 50 %.

In this case, the following applies. The fuse will open when the Zener Diode conducts thereby further protecting the circuit.

When considering the Intrinsically Safe Circuit in a control system, there are three main components: 1) The field device (can be either a simple or non-simple device), 2) The field wiring, 3) The barrier. An Intrinsically safe circuit is typically defined as: Maintaining an intrinsic safety earth is not as difficult as some believe but, particularly when only a few zener Part 25 Intrinsically safe systems Suggested reference book on intrinsic safety and hazardous areas Electrical Apparatus and Hazardous Areas by Robin Garside.

power in intrinsically safe circuits and attempts to demonstrate the type of electrical installation in which the intrinsically safe technique is applicable.

The blue and green curves are the accepted design curves used to avoid spark ignition by resistive limited circuits in Group IIC and IIB gases.

Designing an Intrinsically Safe Device: Embedded Software. Once through the maze of component selection, circuit design, board layout, conformal coating, encapsulation, and inspection, the last area of good intrinsically safe design is the embedded software, as performance can be substantially improved through the optimization of the software.

Intrinsically safe wiring must be designed and installed as a complete system if it is to function as intended and to be Code compliant.

The system consists of intrinsically safe apparatus and circuits. An intrinsically safe circuit is defined as one that is not capable of causing ignition. Intrinsically safe equipment is defined as "equipment and wiring which is incapable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheric mixture in its most easily ignited concentration.".

Widgington, D. W., Some aspects of the design of intrinsically safe circuits, Research Report No. Safety in Mines Research Establishment, Sheffield (). Advanced Intrinsic Safety Circuit Design This 3 day workshop based training is the most advanced Intrinsic Safety designers course available.

This course is for Engineers who wish to master designing intrinsically safe equipment and learn some new methods of achieving safety used in the latest editions of the intrinsically safe standard for. contains both intrinsically safe circuits and non-intrin-sically safe circuits and is constructed so that the non-intrinsically safe circuits cannot adversely affect the intrinsically safe circuits.

NOTE – Associated apparatus may be either: a) electrical apparatus which has an alternative type of protection for use in the appropriate explosive. nonincendive circuits. Intrinsically Safe Circuits and Nonincendive Circuits Intrinsically safe circuits and nonincendive circuits use the same basic concept to minimize the risk of ignition of hazardous atmospheres.

Details Some aspects of the design of intrinsically safe circuits. FB2

Both rely on energy limita-tion with some important differences. Nonincendive circuits are permitted in Division 2 and Zone 2. Intrinsic Safety Circuit Design Intrinsic safety training for ‘product’ designers.

This 2 day introduction to Intrinsic Safety Circuit Design course is ideal for Engineers who wish to start designing intrinsically safe equipment or brush up on their knowledge of this complicated subject and perhaps learn some new methods of achieving safety.

The presenter has conducted or checked hundreds. An intrinsically safe circuit for use in a hazardous environment includes a plurality of circuit sectors (1, 2) which are substantially isolated physically from one another by an electrical insulator, such as air, and are electrically connected, directly or indirectly, so as to define at lease one power transfer path (P1) between each circuit sector (1) and the other circuit sector (2) ; and.

If a circuit is intrinsically safe you could use any piece of equipment because the energy is controlled by the i.s barrier in a safe area.

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So in my mind an i.s. barrier is perfectly acceptable supplying an Ex d/e piece of equipment as it is the highest form of electrical protection.

Simply repackaging a non-intrinsically safe device in an enclosure meant to provide protection from hazardous gas or dust infiltration that could be combustible is often not sufficient. Many handheld devices require an intrinsically safe circuit approach reaching the smallest aspect of the circuit board design.

Source: API RP 14F, Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class 1, Division 1 and Division 2 Locations, Fifth Edition, July Global Standards. Intrinsically Safe Circuit. This comprehensive book provides a unified foundation of wireless communication systems for transmission of data, voice and video, and incorporates intrinsically safe design and development aspects of circuits, which are essential for hazardous areas.

In order to make electrical equipment safe for use in a potentially explosive atmosphere, some form of protection must be afforded. Irrespective of whether you are certifying equipment for the ATEX Directive (for use in Europe) or to international requirements, the fundamental methodologies remain the same.

One of the most commonly used concepts for low power equipment (such as instrumentation.

Description Some aspects of the design of intrinsically safe circuits. EPUB

instrumentation and control applications. Figure 1 illustrates the basic design of an intrinsically safe (IS) loop. Intrinsically safe SPDs Surge protection devices in intrinsically safe circuits must meet the same standards of design and construction as the intrinsically safe equipment, i.e.

IEC specifies inspection and maintenance matters. Maintenance aspects affect apparatus and system design since ‘live maintenance’ is an essential aspect of the intrinsically safe technique and influences some aspects of the design.

The need for adequate instruction manuals is increasingly obvious and should be part of the design. When selecting cells or batteries for use in intrinsically safe devices, take care to ensure that the cells and batteries are robust enough to withstand the expected environmental conditions, as well as to contain or minimize the amount of electrolyte leakage that can occur under severe short-circuit conditions.

Calculating intrinsically safe loop approvals – Part 2 Firstly, and importantly, there is a misconception that the Co values are defined by the design of barrier/isolator. The Co value is actually defined in IEC/SANS Table A.2 page 96 ( of ). Exic offers some flexibility and for upgrades allows for upgrades of old.

The design of intrinsically safe apparatus and systems ensures that the short circuit and open circuit of field wiring cannot produce sufficient ignition. More information on Intrinsic Safety and Intrinsically Safe circuits. We would recommend you to get the Hazardous Area Instrumentation e-learning course, to really understand how intrinsic safety works and how intrinsically.

In this situation, the intrinsically safe apparatus in the hazardous area has to cooperate with the apparatus in the safe area, in which the circuits are partially intrinsically safe. The apparatus in the safe area is called an associated apparatus [5].

The concept of intrinsically safe technology consists of two aspects. Intrinsic safety (IS) is a protection technique for safe operation of electrical equipment in hazardous areas by limiting the energy, electrical and thermal, available for ignition.

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.

In maintaining intrinsically safe and asso­ciated apparatus, no changes or modifications of circuits and construction shall be allowed, In reparing intrinsically safe and associ­ ated apparatus, the following shall be observed: (a) Any components or units of intrinsical­ly safe apparatus, made to be replaced easily, for example, by plug-in.

Any difference means that current must be entering or exiting the load by some means other than the two main conductors, which is not good.

Safe Circuit Design Chapter 3 - Electrical Safety PDF Version. As we saw earlier, a power system with no secure connection to earth ground is unpredictable from a safety perspective. There’s no way to. Have been in to work today, so looked up some information from IEC Use of uncertified apparatus Apart from − simple apparatus used within an intrinsically safe circuit, or − apparatus covered by b), c) or d), the use of uncertified apparatus should be restricted to exceptional circumstances, e.g.The foregoing expedients are highly useful, but not always sufficient to permit the design of an intrinsically safe circuit.

The purpose of the present invention is to supply additional ways of providing an intrinsically safe circuit, and to provide components and circuits useful therein which are simple, inexpensive, and reliable. I need to design intrinsically safe portable apparatus for use in zone 0 in hazardous locations.

It's first project of that kind, I have a fundamental question. I have rad thru IEC and normative documents. There is information, that .