Insulation surge arresters

All electrical equipment are designed for a specific BIL, as indicated in Tables 11.6, 13.2, 14.1, and 32.1(A) for motors, switchgears and bus systems respectively, and Tables 13.2 and 13.3 for the main power system (line clearances and insulators). If the actual severity of a prospective surge, i.e. its amplitude and/or rise time or both, is expected to be higher than these levels (higher amplitude and lower rise time) the same must be damped to a safe level, with the use of surge arresters, surge capacitors or both as discussed later. 

This is the winding insulation to the body, whicli is more vulnerable to prospective voltage peaks. V,. as a result of TRVs. When the TRV exceeds the BIL of the machine, it can be dampened to a safe limit with the use of a surge arrester, say, from peak to ih, as illustrated in Figure 17.21. Details of a surge arrester and the procedure for its selection are discussed below. See also Example 17.6. The selection of the arrester w ill also depend upon the method of star (neutral) formation of the stator s... 

A surge arrester is not able to reduce the steepness (r.r.r.v) of a surge. While motors with single-turn coifs may be safe as turn to turn insulation becomes the same as the major insulation with respect to the body, motors... 

Surge arresters Electrical characteristics of a ZnO surge arrester Basic insulation level (BIL) ... 

Surge arresters. The use of modern surge arresters allows a reduction in the basic impulse-insulation levels of much transmission system equipment. The primary function of early arresters was to protect the system insulation from the effects of lightning. Modern arresters not only dissipate lightning-caused transients, but may also control many other system transients caused by switching or faults. 

MIMS cable systems should be protected by surge arresters to prevent insulation failure if transient voltage surges are hkely. 

He J, Zeng R, Chen S, Tu Y. Thermal characteristics of high voltage whole-solid insulated pol3rmeric ZnO surge arrester. IEEE Trans Power Deliver. 2003 18 1221-1227. 

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