Contents
What is creepage distance in surge arrester?
Creepage distance is the distance on the surface of the housing from high to low voltage end (see Fig. 4). This parameter is critical when an arrester is being applied in areas where there is salt, industrial or other contamination.
What is protective margin of power system equipment?
Steep current impulse protection level, STIPL E.g., for a 33kV system the BIL of transformer is 170kV and LIPL of surge arrester is 90kV then 80 kV is the protective margin. The protective margin should be high enough to take care of lead lengths, separation distance and aging effects of equipment to be protected.
What is gap surge arrester?
It is a protective device which conducts the high voltage surges (due to both direct and indirect stroke) on the power system to the ground and protects the equipments connected to it. Rod gap is the simplest form of Lightning arrester used for the protection of electrical apparatus.
Which utility surge arresters are best?
Station class arresters offer the best discharge voltages of all arresters, provide high energy handling capabilities, have the highest fault current withstand capability and are available in ratings from 3 to 684 kV.
What is Type 2 surge arrester?
The Type 2 SPD is the main protection system for all low voltage electrical installations. Installed in each electrical switchboard, it prevents the spread of overvoltages in the electrical installations and protects the loads. Type 2 SPD is characterized by an 8/20 µs current wave.
What happens when a surge hits an arrester?
Unfortunately, separation distance (or protective zone) of this magnitude can result in reduced protection when a fast rising surge enters the station from an overhead line at nearly the speed of light. When the surge hits the arrester, voltage is indeed reduced – but not to zero and, at best, to the discharge voltage of the arrester.
Where is the surge arrester located at a substation?
Fig. 3: Shielding failure – Computed overvoltage magnitudes at SGT terminals versus surge arrester distance from equipment. In this model, the lightning stroke is applied on the earth wire at a point located 0.9 km from the substation.
How big of a distance does an arrester need to be?
No overvoltage protection is offered by arresters at distances greater than 20 m. Fig. 4: Backflashover event – Computed overvoltage magnitude at SGT terminals versus surge arrester distance from equipment (red line), and in case of surge arrester absence (blue line).
How are arrester protection distances at substations determined?
In scenario S1 (comprising the SG Transformer, the AIS and the overhead line, as shown in Fig. 2), maximum overvoltage magnitudes were computed at the super grid transformer, installed within the air insulated substation, for both lightning and switching events. Effective protective distance of arresters can then evaluated for each event.