HV Current-limiting Fuses for Transformer Protection

lt can be used in indoor system of 50HZ and rated voltage of 3.6KV, 7.2KV, 12KV, 24KV, 40.5KV; Used together with other switch facilities such as loading swithes, vacuum contactors, it can protect electric transformers and other electric facilities against overloading or circuit break. It is also a necessary accessory for high-voltage switchbox，circular circuit cabinet, high / Low voltage top-loading transformer substation.

1. End cap

2. Porcelain Tube

3. Arc extinguishing filler

4. Fuse element

5. Coil resistance

6. Impactor

7. Star-shaped skeleton

Technical Data

Considerations for Transformer Fuses

To ensure proper transformer protection, in addition to considering the transformer's full-load current, allowable overload current, and surge current, the following selection principles should also be considered:

1. The fuse's time-current curve should lie to the right of the transformer's surge current.
2. The fuse's rated current should meet the transformer's full-load current.
3. If the fuse is installed in an enclosed cabinet or the ambient temperature exceeds standard requirements, consider derating.
4. The secondary-side high-voltage fuse and the secondary-side low-voltage protective device should 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 converted to the high-voltage side) should be greater than the maximum high-voltage short-circuit current caused by a secondary-side short circuit.
5. The pre- and post-breaking currents of a fuse without a striker should be less than the maximum breaking current of the switchgear with which it is used. 6. When the transformer secondary side is grounded and short-circuited, the transformer primary side phase current distribution ratio will be 1:2:1. At this time, the maximum current on the primary side will be 3/2 times the normal conversion factor. This situation must be taken into consideration when selecting a short-term solution.