high voltage zov varistor

Specifications

1. Introduction of MOV:

In medium-voltage distribution systems the arresters are widely spread over the whole network as they are normally directly arranged either, for instance, at the pole-mounted transformers, or at the cable terminations.

Certain designs of the polymer housed arresters were in fact impossible to construct until the gapless metal-oxide technique was introduced. As a major progress, metal oxide arresters could be built with only one single effective active element, namely the column of the metal oxide resistors.

2. Function of MOV:

 High demands are, however, made on these metal oxide resistors, as they combine all the functions, which previously had been shared among the different components of the gapped arrester. In this way they have to be ageing resistant while being subjected to constantly applied operating voltage.

They must be able to absorb the energy injected during a discharge, and they should subsequently limit the follow current (leakage current) to value small enough for thermally stable operation.

The metal oxide varistors used in the arresters provide high energy absorption and low residual voltages. Multiple high current lightning and low duration switching surges are absorbed without noticeable changes in the arrester characteristics or stability.

 3. Construction:

MO resistors vary in height between  22mm and 45mm. For the most part, the height is associated with the production and depends on the available tools and manufacturing facilities. However, not every height can be manufactured, since the greater the height (as well as the diameter), the harder it is to achieve sufficient homogeneity of the resistor material during manufacturing. This, however, decides most of all upon the energy absorption capability and even more upon the reproducibility of specified technical data.

4. Specification: 

• D5-35KV
•  Φ48
• 4/10μs big current: 100
• 2ms rectangular wave: 450A

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