Product Overview

This product is suitable for indoor AC 50Hz systems with a rated voltage of 3.6–40.5kV. It can be used in conjunction with other switchgear such as load break switches and vacuum contactors, serving as a protection element against short circuits and overloads for power transformers and other equipment. It is also an essential accessory for high-voltage switch cabinets, ring main units, and prefabricated high/low voltage substations.

Model Designation Explanation

Product Structure Diagram

Overall and Installation Dimensions

Overall and Installation Dimensions

Selection Reference Table

Considerations for the Application of Fuses Protecting Transformers

To ensure adequate protection for transformers, in addition to considering the transformer's full-load current, allowable overload current, and inrush impact current, the following selection principles must also be applied:

1. The time-current characteristic curve of the fuse must lie to the right of the transformer's inrush impact current.

2. The rated current of the fuse must be greater than or equal to the transformer's full-load current.

3. If the fuse is installed in an enclosed cabinet or if the ambient temperature exceeds standard requirements, the fuse must be used with a derated current rating.

4. The high-voltage fuse on the primary side and the low-voltage protective devices on the secondary side must be properly coordinated. The current corresponding to the intersection of the high-voltage fuse's time-current characteristic (minimum pre-arcing) and the low-voltage protective device's characteristic (maximum total operating characteristic, appropriately referred to the high-voltage side) must be greater than the maximum short-circuit current on the high-voltage side caused by a secondary-side fault.

5. The breaking current values (both before and after arc initiation) of fuses without strikers must be less than the maximum breaking current rating of the switchgear they are used with.

6. When a transformer experiences a secondary-side earth fault or phase-to-phase short circuit, the phase current distribution on the primary side will be 1:2:1. Under this condition, the maximum current experienced by the primary side is 3/2 times the normal transformation coefficient. This factor must be considered when selecting fuses for short-circuit withstand capability.