Variable frequency drive and a method for reducing earth leakage and protect the transistor earth leakage, and how to protect TRANSISTOR

摘要

FIELD: electricity.;SUBSTANCE: wider application of variable-frequency drives (50) determines the tasks related to their compliance with certain requirements of various applications. For many reasons, including safety instructions and electromagnetic interference, earth leakage current decrease is required. According to economic considerations it is necessary to manufacture drives (50) with high output voltages by using transistors, the nominal voltage of which is less than output voltage of variable-frequency drive. The latter and method of decreasing earth leakage current and protection of transistor allow solving these tasks and others by arranging electrically insulating plate (cp176) with high heat conductivity, small dielectric constant and high dielectric strength between ribbed radiator of power semiconducting module of variable-frequency drive and grounded cooling plate (80TE).;EFFECT: decreasing earth leakage current induced with capacities of system to the earth at drops of radio-frequency voltage, and increasing effective dielectric strength of transistor modules of drive, which provide output voltage of high-reliable drive at the specified nominal voltage of transistor.;21 cl, 8 dwg, 3 tbl