The circuit reristance value which is often used to estimate the contact quality of circuit breaker is one of the most important technical parameters

The resirstance value has freguently been beyond the tolerance limit or become unsteady

as a result mang guality trouble events come about and much repair work has to be done. Based on prof. Takuchi Ganic-hi’s Experimental design method. the key position has been found out; the main effective sources has been analyzed; a orthogonal experiment of circuit breaker units was carried out and improvement has been put forward. All of the calculation and analysis are completed by microcomputer.