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In a TT (terra–terra) earthing system, just as with a TN system, there is a direct connection to Earth at the supply transformer. But, unlike TN, the exposed-conductive-parts at the consumer installation are independent from it, instead having an entirely separate connection to Earth via a local earth electrode (sometimes referred to as the ...
Utilization factor (solid line) with blade-to-gas speed ratio. The utilization factor or use factor is the ratio of the time that a piece of equipment is in use to the total time that it could be in use. It is often averaged over time in the definition such that the ratio becomes the amount of energy used divided by the maximum possible to be used.
A grounding transformer or earthing transformer is a type of auxiliary transformer used in three-phase electric power systems to provide a ground path to either an ungrounded wye or a delta-connected system. [1] [2] Grounding transformers are part of an earthing system of the network.
An isolated ground (IG) (or Functional Earth (FE) in European literature) is a ground connection to a local earth electrode from equipment where the main supply uses a different earthing arrangement, one of the common earthing arrangements used with domestic mains supplies.
Added earthing on lighting circuits. Reprinted with amendments in 1968 and 1969, a supplement was issued 'on use in metric terms' in 1969, amended and reprinted 'in metric units' in 1970, reprinted in 1972 and 1973, amended and reprinted 1974 and 1976. 1981: 15th: IEE: Entitled 'Regulations for Electrical Installations'. Issued with red cover.
This page was last edited on 30 July 2005, at 20:48 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...
This case is a simplified system; practical earthing systems are more complex than a single rod, and the soil will have varying resistivity. It can, however, reliably be said that the resistance of a ground grid is inversely proportional to the area it covers; this rule can be used to quickly assess the degree of difficulty for a particular site.
A wire break in the fault to load section, or in the earth to ground section, will disable operation of the devices. Requirement of an additional third wire from the load to the devices. Separate devices cannot be grounded individually. Any additional connection to Earth on the protected system can disable the detector.