This paper put forward a method to improve the boiler by adding side-secondary air (SSA) to the primary air (PA) , dealing with the ubiquitous coke phenomenon of the 670T/H boiler in the thermoelectricity factory of DaQing oil fields and the lignite boiler in northeast area of China.

In order to study the transient disturbance signal of the secondary side of PT, which is generated by disconnector switching in 500 kV substation, a test is made in the field and the time and frequency domain character in details, such as the pulse peak, the number and the interval time of the pulses and the spectrum of signals are obtained.

Measures the secondary side disturbance signal of CT in 500kV insulated sw itch operations on-site in substation, analyzes and gets the secondary side pulse peak value of CT, pulse number, pulse interval, interference signal spectrum and other time and frequency domain characteristics.