Safe electrical systems

Specifications for intrinsically safe electrical system i General recommendations on the selection of the appropriate group of electrical apparatus based on safe gaps and minimum igniting currents 3682/1991 BS 5501-7/1977 BS 5501-9/1982 BS 5345-1/1989 ... 

When planning intrinsically safe electrical systems it shall be taken into account that the handheld terminal may be connected to the intrinsically safe... 

The inherent disadvantages of the underground system are high first cost, inconvenience, and excessive cost of maintenance. Overhead construction is often used since it can be installed at about one-third the cost of the underground system, and repairs can be quickly made. However, such lines are exposed to impairment by weather, lightning, trucks, cranes, and corrosion, so that overhead construction should be avoided in congested areas where a reliable and safe electrical system is necessary. 

Standards and codes have been developed over the years to ensure that we have safe structures, safe transportation systems, safe electrical systems, safe drinking water, and safe indoor/outdoor air quality. A tine is a good example of an engineered product that adheres to such standards. There are many national and international standardization organizations that set these authoritative standards. Standards and codes also ensure uniformity in the size of parts and components made by various manufacturers around the world. 

In general, it is an essential of a safe electric system that everything which might come into contact with a live system be maintained at ground potential. Further safety is gained by providing the system with a grounded nentral leg in the system. 

Controls, instrumentation, and electrical systems in a gas turbine are defined. The outline in the standard is the minimum a user needs for safe... 

FPN No. 3) ft is not good practice to install electrical equipment in Zone 0 locations except when the equipment is essential to the process or when other locations are not feasible. (See Section 500-2.) If it is necessary to install electrical systems in Zone 0 locations, it is good practice to install intrinsically safe systems as described by Article 504. 

No maintenance task can be issued without the person responsible for controlling the workforce establishing that the work is to be carried out safely. Areas where this is essential would include boilers, pressure systems, electrical systems, confined spaces, hot work, deep sumps/shafts, tanks, and lone working. 

First, once designed, evaluated, and installed, the safety of the system cannot easily be degraded because the safety is in the design, not protection added afterward. In fact, the intrinsically safe electrical circuit will cease to fulfill the function for which it was designed long before it can become a hazard. This is due to the consideration which must be given to fault conditions. The only possible way for the circuit to become hazardous is if an unapproved or unauthorized component is substituted into the circuit. 

Intrinsically safe electrical circuits provide the capability to combine the strengths of pneumatic and hydraulic systems with the sophistication of the programmable controllor and robotics, and to do so with the maximum safety and flexibility. 

S1 r s plasma fog jet watercar approach is one of the simplest, yet most effective and safe approaches to creating a water powered car. It only requires an electrical system that can deliver 5-10 amps and 14,000+ volts to the spark plugs at each firing. There are any number of different ways that this can be accomplished using off-the-shelf parts and equipment. 

EN 50039 Intrinsically safe 1st electrical systems i Part B Electrostatic spraying equipment 1980-03 1st VDE 0170/ 0171 Teil 10 1982-04... 

If a high quality equipotential bonding system cannot be put into practice or a steady supply voltage cannot be guaranteed, a galvanic isolation between intrinsically safe and non-intrinsically safe electrical circuits is recommended. Such apparatus, e.g. power supplies for transmitters or switching repeaters, are equivalent to safety barriers with respect to the philosophy of intrinsic safety. The additional feature may be seen in the galvanic isolation and functional characteristics which may be practicable. 

The further development of the FISCO model will be incorporated into international standardization as IEC 60079-27 Electrical apparatus for explosive gas atmospheres, FISCO-Concept for HI intrinsically safe Fieldbus systems. In this standard, the safety-related data will be specified in detail ... 

Underwriters Laboratory (UL)—Determines whether equipment and materials for electrical systems are safe in the various NEC location categories. 

Some of the problems associated with electrical systems have been covered in previous sections, such as Chapter 3, Section LG. There may be some unavoidable repetition in this section, which will be primarily concerned with the safe use of electricity rather than the characteristics of individual items, although there will be a brief discussion of generic problems associated with the design of equipment. Most of the hazards associated with the use of electri-... 

The provision of a safe eiectrical system is fundamental to the whole concept of using eiectricity in and around buildings safely. The electrical installation as a whoie must be protected against overload and short-circuit damage, and the peopie using the instaiiation must be protected against electric shock. 

All electrical installations and installed equipment must be safe to use and free from the dangers of electric shock, but some installations or locations require special consideration because of the inherent dangers of the installed conditions. The danger may arise because of the corrosive or explosive nature of the atmosphere, because the installation must be used in damp or low-temperature conditions or because there is a need to provide additional mechanical protection for the electrical system. Part 7 of the lET Regulations deals with these special installations or locations. In this section we will consider some of the installations which require special consideration. 

State three safe working procedures relevant to the safety of other electrical systems when carrying out electrical testing. 

Conditional evidence. This type of evidence is produced by an event or action and includes direction of the smoke stains, the speed at which the fires spread, the amount, type, and degree of melted material, the condition of the electrical system and fuse box, the condition of the fire alarm and/or smoke detectors, and the location of the safe, important documents, and valuables. This type of evidence often can be used to determine the cause of the fire and/ or be used to reconstruct the fire. 

The design of the instrumentation, control and electrical systems corresponds with the safety concept for safe reactor operation, and advanced electronic and information processing technology has been incorporated in the design. The plant is automated to a high degree, and all safety precautions are taken into account. The plant control scheme is based on "the reactor follows plant loads principle". 

The System 80+ Standard Design includes improved design features and electrical systems to ensure a safe shutdown of the reactor in the event of a station blackout. These improvements are summarized below ... 

A module has a power rating of 170 MW(th) at 950°C helium outlet temperature for process heat applications, while for electricity production or coproduction of electricity and process steam or district heating a rating of 200 MW(th) at an exit temperature of 700 °C is achieved. For reasons of economics and demand, plant sizes of 8 units appear to be an upper limit. Additionally the modular HTR as a small and inherent safe reactor system fullfil the criterion for the design of an autarc barge-mounted energy station in an optimum way. 

---