Principle characteristics and reasonable selection of high-voltage current-limiting fuses

Principle of High Voltage Current Limiting Fuse

First of all, this component has the two major characteristics of current limiting and rapidity. After the protected line fails, the highest current peak is usually in the first half wave, so when the shell is broken, all short-circuit currents are equal. Can be transferred to high-voltage current-limiting fuse. At the same time, the short-circuit current has not fully risen in the first half of the wave, and the fuse will vaporize, breakdown, and the arc generated by the gap and extinguish the arc, limiting and compulsively cutting off the short-circuit current (total It takes less than 2 milliseconds), so the high-voltage current-limiting fuse realizes that the current cannot reach the expected short-circuit current peak value.

If the short-circuit current rises to Ip, the fuse will perform fusing and complete the cut-off action, so that the cut-off current Ip range is only about 15% of the expected current peak value, which can effectively make the fault current affect the power generation and substation equipment. And thermal impact is greatly reduced. The arc voltage produced by the high-voltage current-limiting fuse can be limited by using a non-linear resistance, and at the same time, it can better solve the problem of insufficient capacity of the fuse and increase the practical application range of the entire device. , The above is the principle of high-voltage current-limiting fuse.

Features of high-voltage current-limiting fuse

◆The breaking capacity is relatively high, and the breaking current can reach 63kV;

◆The power is small and the temperature rise is relatively low;

◆Ampere-second characteristic error is less than ±10%;

◆The reaction speed and execution of the high-voltage current-limiting fuse are very fast. When the rated current of the fuse-link of 100A passes the expected current of 1000A, the time before the arc will not exceed 0.1 seconds;

◆ Equipped with the spring striker has the characteristics of large contact surface and low pressure, so when the switch linkage lock is pushed, it will not break down the contact surface of the switch and the striker;

◆The specifications of high-voltage current-limiting fuse are standardized, which can play a great role in current-limiting, and can reliably break any fault current between the minimum breaking current and the rated breaking current.

Selection of High Voltage Current Limiting Fuse

To be precise, this fuse is a relatively simple structure and a component that provides reliable protection. It is precisely because of the high-voltage current-limiting fuse that is small in size and must have high-precision technology, craftsmanship and quality. In other words, how to select it correctly is also a key issue for it to better display its characteristics in future work. Therefore, when choosing a high-voltage current-limiting fuse, the following factors need to be considered.

1. Installation environment requirements

The environmental conditions used by the equipment is a very important factor. It not only affects the performance but also affects the ability to safely disconnect the fault to a certain extent. Therefore, it needs to be properly considered and selected. In the actual application process, a common installation method is to place the high-voltage current-limiting fuse in a three-phase enclosed box. At this time, the rated current of the equipment must be reduced by 15% before use. If the rated current of the device is less than 20A, you do not need to consider derating. The main reason is that the fuse with a small rated current generates less heat and has a relatively low temperature rise, so the actual impact of the enclosed environment on it is not large.

2. Principles of closure characteristics

Ip total = n* (Ip1 when the expected current of a single high-voltage current-limiting fuse is Ip/n), where Ip always represents the peak interception after paralleling, Ip1 represents the peak interception of a single device, Ip represents the effective value of the expected current, n Indicates the number of fuses in parallel.

The above are the principle features and reasonable selection of high-voltage current-limiting fuses. I hope to help everyone.You can log in to the okplazas.com motor mall to view the product information of the fuse, welcome to email: [email protected] for consultation, and you can also contact WeChat customer service +86-13689242098 online for product consultation!