This article introduces to affect four factors of electrical life of the contactor,that is usage category;rated current;operating frequency and working environment,and improves the electrical life of the contactor from this analysis.

In the mcs51 system used 6 or 12 MHz oscillation frequencies, to measure the digital to analog converting speed and reliable operating frequency of the DAC0832 circuit.

The vacuum circuit breaker developed in recent years is a new product with many special advantages such as reliable operation, easy maintenance, big capacity, frequent operation and so on.

Quality of the refactory brick in rotary kiln affects directly the normal production and product quality and the production cost,the main damage factors are analysed in detail,including action of stress pressure,unreasonable setting of inlet end ring,nonstandard masonry of refractory brick and relaxed operation system,and etc.

Through improving the quality of raw material,strengthening the management of raw material and fuel,perfecting the operation system of the furnace and promoting operating level,the 450m3 BF at Taigang is enabled to keep stable and smooth furnace conditions.

The operation system, steady and smoothly operating and strengthening smelting of 450m3 blast furnace in Tangshan region are introduced in simple, the relation between them stated, some existing problems pointed out, some measures to improve things mentioned above proposed.