4.3　Circuit breakers and arresters

Ⅰ　General requirements

4.3.1　The circuit breakers and the arresters include independent circuit breakers，free standing arresters and tie-rod arresters.

4.3.2　Aseismatic appraisal for the circuit breakers and the arresters shall focus on the examination of the porcelain insulators，the connections between porcelain insulators and flanges，and the strength of tie-rod and external conductors at each direction.

4.3.3　In the areas where the aseismatic precautionary intensity is 7 degree and above，the circuit breakers and the arresters shall be seismically calculated in accordance with Chapter 5 of this standard.

Ⅱ　Aseismatic appraisal

4.3.4　Aseismatic appraisal for the circuit breakers and the arresters shall meet the following requirements:

1　The porcelain insulators of the circuit breakers and the arresters shall be in good conditions.

2　The porcelain insulators and the flanges shall be firmly attached.

3　The bases and intermediate flanges of the circuit breakers and the arresters shall be in good conditions，and the nuts shall not be loose.

4　The external conductors of the circuit breakers and the arresters shall be flexible conductor or provided with flexible fittings.

4.3.5　For the arresters provided with insulated tie-rods，the strength of the tie-rods at each direction shall be uniform.

Ⅲ　Aseismatic measures

4.3.6　If the circuit breakers and the arresters fail to meet the aseismatic appraisal requirements specified in this section，aseismatic precaution measures shall be taken in accordance with the following requirements or shock-absorbing measures shall be taken in accordance with Appendix A of this standard.

1　The damaged or cracked porcelain insulators of the circuit breakers and the arresters shall be replaced with good porcelain insulators.

2　The bolts used to fix the porcelain insulator and the flange shall be tightened.

3　If the bases and intermediate flanges of the circuit breakers and the arresters are corroded，rust shall be removed and nuts shall be tightened.

4　If rigid bus or tubular bus is used as the external conductors for the circuit breakers and the arresters，flexible conductor or flexible fittings shall be provided.

4.3.7　For the arresters with insulated tie-rods，the strength of the tie-rods at each direction shall be uniform.If the insulated tie-rods are damaged or fail to meet the strength requirements，they shall be replaced. Yau0qthw7TPPXNxjyL5Wv2swrgiwMV+Ir0RiNFhaxC99xBpzXcuBlM5N6A1IIB7i