基于PLC的高压电机软启动装置的设计(4)

绝对最后完成版毕业设计论文 格式正确,文字严谨

ABSTRACT

Ordinary rat trap type motor in the full pressure no-load direct starting， will reach the starting current rated current of the five to seven times，when the relatively large capacity motor，the starting current will cause the network voltage drop dramatically and it would damage with the normal operation of the power grid other equipment，can cause even power grid lose stability，cause more accidents. Motor starting the full pressure when direct current motor stator coil and turn in the article cage produce a lot of impact，will destroy winding insulation and cause article rat trap fracture， fault caused by motor，large current also will produce large amounts of the joule heat，damage winding insulation， reduce motor life. Motor starting the full pressure when directly starting torque is about the rated torque of 2 times，for gear transmission equipment for，a lot of impact will make gear speed up even wear broken，for belt drive equipment，it increases the belt wear even tensile belt.This design for high voltage motor start and design，USES the switch transformer for soft starter，using thyristor as its switch device， through PLC control thyristor opened and shut off，through the change voltage of the motor，reduced to start. This device is suitable for the high frequency frequent start，small startup current，the device，the characteristics of small loss.

Keywords：switch transformer； Thyristor； PLC； Motor soft starter