Electrical switchgear/circuit breakers

Electrical switchgear, circuit breakers, switches, and small transformers are normally grouped together in a building or Motor Control Center (MCC). Climate controlled buildings may also be required to house minicomputers, transducer banks, and other instrument interfaces. Putting this equipment in a building protects it from fires and explosions in the process area. 

BS 5311, High voltage alternating current circuit breaker BS 6867, Code of Practice for maintenance of electrical switchgear for voltages above 36 kV BS 158, Insulating oil for transformers and switchgear BS 5622, Insulation co-ordination... 

Inclusion of thermography into a predictive maintenance program will enable you to monitor the thermal efficiency of critical process systems that rely on heat transfer or retention electrical equipment and other parameters that will improve both the reliability and efficiency of plant systems. Infrared techniques can be used to detect problems in a variety of plant systems and equipment, including electrical switchgear, gearboxes, electrical substations, transmissions, circuit breaker panels, motors, building envelopes, bearings, steam lines, and process systems that rely on heat retention or transfer. 

Situations occur, especially with offshore platforms, where no physical space is available to install an extra generator and its associated equipment. Sometimes the main switchrooms cannot accept any more switchgear, not even one more generator circuit breaker. Therefore the potential for upgrading a prime mover without having to make major changes to the electrical system is an option that should be considered seriously at the beginning of a project. 

Circuits are controlled by switchgear which is assembled so that the circuit may be operated safely under normal conditions, isolated automatically under fault conditions, or isolated manually for safe maintenance. These requirements are met by good workmanship carried out by electrically skilled persons and the installation of approved British Standard materials such as switches, isolators, fuses or circuit-breakers (IET Regulation 131.1.1). The switchgear must also be non-combustible or housed in a non-combustible cabinet or enclosure (IET Regulation 421.1.200). The equipment belonging to the supply authority is sealed to prevent unauthorized entry, because if connection were made to... 

Sulfur hexafluoride is used extensively as a gaseous dielectric in various kinds of electrical power equipment, such as switchgear, transformers, condensers, and circuit breakers. It has also been used as a dielectric at microwave fre... 

Circuit breaker coordination is a good engineering practice that can limit the degradation of safety related systems during a fault condition on a system component. Without coordination between breakers, an electrical fault on one component, such as a motor or motor-operated valve, could result in the loss of an entire motor control center or switchgear bus instead of just the single faulted component. 

Another example is the selection and use of suitably insulated cables. Their voltage and current ratings should not be exceeded where this might cause an insulation failure and the consequential exposure of a live conductor that would produce the risk of electric shock and bum injuries to anyone who may touch it. Yet another example is high voltage switchgear, such as circuit breakers. These devices may be required to clear short circuit faults on... 

There is a report on the Carbon Membrane Separator for elimination of SFg from gas insirlated electrical utilities [7]. In the electrical power industry 80% of 6,500-7,500 metric t SFg produced worldwide is used as a gaseous dielectric in circuit breakers, gas-irrsulated substatiorrs and switchgear. Besides its high price, SFg is a very potent greenhoitse gas. A possible way to captirre and reuse the SFg in the... 

The mechanical endurance of the current-carrying parts of all the equipment, bus system, deviees and components, used in a particular circuit as well as the load-bearing members and supports on which they are mounted. The electrical parts of a device (breakers and switches, etc.) are the responsibility of the component manufacturers. The manufacturer of the switchgear assembly is responsible for the busbar systems, metallic links and wires. 

These may be used to feed the solenoid or the motor of an interrupting device (such as an electrically operated breaker), indicating lights and circuits, auxiliary contactors or relays, electrical or electronic timers, hooters or buzzers, and all such auxiliary components and devices mounted on a controlgear or a switchgear assembly requiring a specified control voltage. 

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