Application of varying frequency speed controller in heating hydrotech system of constant pressure;

The control principle of pressurization by make-up water for heat-supply system of residential areas is analyzed, the study is made on the pressurization methods by make-up water of elevated expansion tank, make-up water pump and pressurization water tank, and it is not necessary for heat-supply system of residential areas to apply the variable frequency make-up water pump.

With an expatiation on the mechanism of power supplying using reciprocal transformer,the article explores and discusses several solutions for power supply.

The paper analyses the reasons why electricity energy made use of the city street lamps illumination consumes bigger and service life of the street lamps is short, puts forward the solution which adopts compensated transformer regulating voltage mode and P89C51RD2 microcontroller to control the voltage steady, and designs energy economizer of intelligent street lamp.