High voltage systems

This is more pronounced on high-voltage and extra-high-voltage systems (66 kV and above) when ... 

A similar format of certificate would suffice as a permit to work for high-voltage systems (i.e. exceeding 1000 V). 

RAPPER INSULATOR HIGH-VOLTAGE SYSTEM SUPPORT insulator... 

Uses. In organic synthesis to introduce F atoms into organic molecules oxidizing agent in rocket fuels insulator for high-voltage systems... 

All conductors are part of three closed current loops with impressed currents which are kept constant, and a three-phase high voltage system enables simultaneous PD measurements in the three conductors (Fig. 8.9). The complete test circuit is installed in a shielded cabin as a Faraday cage, all power lines enter this cage via filter banks to suppress unwanted signal transmission to the internal test circuit. The main parts of the test circuit are ... 

Corrosion plays a high risk underground, in particular to aluminum which is totally unacceptable. The electrolytic properties of some soils cause corrosion to all these metals, as do stray currents produced by DC railway lines on DC high voltage systems where the earth is used as a return path. Cathodic protection can help eliminate this type of problem. 

Figure 11.1 One-line diagram of fanlted high voltage system.

It can be seen that for most of the circuit items their X-to-R ratio is more than 10. Hence their resistance may be neglected for fault calculations but this only applies to high voltage systems, e.g. above 3300 volts. The X-to-R ratio of LV components is usually low, e.g. between 1 and 3. 

Figure 13.2 Earthing circuit of leakage capacitance in a high voltage system.

See also sub-section 13.3.3 for a description of the lEC standardised earthing circuits for low and high voltage systems. 

Figure 13.3 Earthing a high voltage system by using a neutral earthing resistor.

Electrical work Work on electrical equipment and on low and high voltage systems with the hazard of a dangerous electric shock Access to electrical installations... 

Access Prevention of active parts no procedure to prevent unauthorized persons working on low/high voltage systems 0.16 0.21... 

---