IEEE Std C37.12-2018 pdf download – IEEE Guide for Specifications of High- Voltage Circuit Breakers (over 1000 V).
4.5.2 Out-of-phase withstand voltage Users should be aware that IEEE Std C37.04-1999 does not define an“out-of-phase”voltage withstand rating for the circuit breakers, and IEEE Std C37.09 does not have any test method to demonstrate this capability. The users may include the following statement for the circuit breaker to be used for synchronizing operations. “The circuit breaker shall be capable of withstanding an out-of- phase voltage across the terminals with the phase angle between the two voltages continuously varying. The duration of out-of-phase voltage withstand shall be (xx).” This requirement is to assure that the circuit breaker, in the open position is capable of withstanding voltages to which it can be subjected under such conditions as systems being out of phase. The duration for this condition should be specifed by the user. The duration of ten minutes is usually sufficient. If out-of-phase conditions are expected to remain longer, it may be a better application solution to specify a circuit breaker having a higher rating. Users and the circuit breaker manufacturer should mutually agree on the circuit breakers out-of-phase voltage withstand and out-of-phase current interruption capability. . 4.6 Construction 4.6.1 General This subclause describes the user s requirements for the support structures, type of hardware, paint color and special paint process if any, etc.
4.6.2.2 Materials Materials used in the insulation structure of circuit breakers shall, wherever practicable, be of a type that would not support combustion, produce toxic gases, or absorb moisture. When subjected to an electric arc, the emission of conducting materials from the insulation structure shall be so limited that it shall not interfere with the required performance of the circuit breaker. 4.6.2.3 Mechanical strength The mechanical strength and physical characteristics of the insulation structure shall be such that the structure will withstand the shocks and other mechanical loads of circuit breaker operations within its ratings, reasonable strains of connecting conductors, and usual service conditions as specified by IEEE Std C37.04 or as specified by the user. Where hydrophilic insulation is used, means such as heaters may be provided to reduce condensation.