Why surge arrester for transformers

Intermediate arresters offer better discharge voltages, have a high fault current withstand capability and are available in ratings from 3 to kV. 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 kV.

Station class arresters have varying cantilever strengths for the most demanding applications. Surge and lightning arresters. Surge Arresters: fundamentals of surge arresters.

What is a surge arrester? Quick links to surge arrester fundamentals: Use Operation Types Learn more. Why use a surge arrester? Surge arrester operation. How does a surge arrester work? Why do arresters operate? Arresters can operate due to a variety of reasons: TOV condition lasted too long Undersized arrester Lightning surges experienced were greater than the duty rating Gap degradation in silicone carbide arresters Deterioration of oil-based polymer housing due to the leaking of the silicone oil additive Wildlife Disk aging Porcelain arresters may break apart after experiencing an end-of-life event, whereas polymer arresters may experience a blow out the side or the disconnector will operate which will separate the arrester from ground.

Types of surge arresters. Secondary arresters Secondary arresters are arresters rated under V. Lighting arrester are also known as surge arrester in electrical engineering. Apart from protect high voltage transmission lines, theses arrester are sue to protect electrical equipments from lightning and surges. High voltage occurs due to lightning create insulation failure in transformers and other electrical devices in transmission system.

Hope that you have gain some basic knowledge about the principles of lighting arrester. Your email address will not be published. The voltage on unfaulted phases at locations away from the fault and away from the grounding transformer location would be higher.

Higher fault current allows for improved relay protection coordination with downstream protective equipment. However, even though grounding transformers improve relay protection coordination, decisions regarding installing grounding transformers and selecting their impedance to increase line-to-ground fault current at a particular location should be evaluated case-by-case.

Surge arresters should be placed for protection of station equipment, including transformers, reactors, capacitor banks, circuit breakers, underground power cables, etc. In order to select and apply the appropriate surge arrester to protect corresponding equipment, the following steps need to be considered.

Note that the focus here is on Temporary Overvoltage TOV evaluation, which governs the selection process for surge arresters used on ungrounded sub-transmission systems.

Additionally, determination of separation distance Step 2 is concentrated as well. A surge arrester shall be located as close as possible to the equipment to be protected; 2.

Otherwise, calculation is needed to determine maximum allowable separation distance between the equipment to be protected and the arrester. If so, Step 4 can be bypassed. Gather surge arrester protective levels, including lightning impulse protective level LPL , front-of-wave protective level FOW and switching impulse protective level SPL ; 2. Gather equipment insulation levels, including basic lightning impulse insulation level BIL , chopped wave withstand CWW and basic switching impulse insulation level BSL ; 3.

Step 4: Evaluate Alternates. Decreasing arrester separation distance; 3. Adding additional arresters; 4. Using arrester with lower protective characteristics. Select a surge arrester MCOV rating equivalent to or greater than the maximum steady-state line-to-ground system voltage at the arrester location. Surge arresters are installed on a transformer to protect it from over-voltage transients. A surge arrester is connected to each phase conductor just before it enters the transformer.

The surge arrester is grounded, thereby providing a low impedance path to ground for energy from an over-voltage transient if one occurs.