Aimed at the contentious problems of main wquipment protection, such as main protection of stator winding trouble, differential protection for transformer, earth fault protection for big generator and transformer etc, the author proposes the clear viewpoints and appeals for greater effort into the application on main equipment protection.
The problems existing in grounding protection of low voltage distribution system in petrochemical enterprise are pointed out together with their harmfulness. Practical examples are analyzed and countermeasures proposed.
This kind of intellectualized unit based on 87C196KC singlechip has several functions as electric power parameter measurement,over-current and earth-fault protection,communication and status monitoring for switchgears.
Several different protection ways for earth fault are introduced and discussed from earth-fault protection, zero-sequence protection, residual current protection and other aspects. Author points out that only combined with equal potential connection satisfied protect effect can be developed.
The new generation of moulded case circuit breakers developed by main electrical companies abroad was introduced in the recent years,and their technical parameters,the feature of structure of the products,the developing trend of technology,for example double-gap contacts system,electronic release,communication-capable circuit breaker,earth-fault protection and residual current protection etc. were expatiated,so as the development of the moulded case circuit breakers abroad was introduced completely.