1 外文文献原稿和译文 原 稿 The water supply system is the national production and life indispensable important one annulus. The traditional method of water supply area, water pollution, infrastructure investment, but the main drawback is that water can not be kept constant, causing part of the equipment can not work normally. Variable frequency speed control technology is a new mature AC motor stepless speed regulating technology, its unique excellent control performance is widely applied to the speed control field, especially in water supply industry. Due to the safety in production and the water quality of special needs, for constant pressure water supply with the stringent requirements, so the frequency control technology has been more in-depth application. Constant pressure water supply ways to advanced technology, constant pressure, convenient operation, reliable operation, energy saving, high degree of automation, in pump station water supply can perform the following functions: ( 1) to maintain constant pressure; ( 2) the control system can be manual or automatic operation; ( 3) a plurality of pump automatic switch operation; ( 4) system of sleep and wake, when people stop when water, the system is in a sleep state, until the water demand automatically wake; ( 5) adjusts the PID parameters on line; ( 6) pump unit and circuit protection detection alarm, signal display. The actual pressure of the pipe network feedback and a given pressure were compared, when the pressure of a pipe network is low, increase the output of frequency converter, pump speed faster, water supply quantity increases, forcing the pipe network pressure rise. Vice pump speed slow down, reduce the water supply pipe network pr...
