PTC current limiting device having molding part made of insulating material

Abstract

Disclosed is a PTC (Positive Temperature Coefficient) current limiting device for limiting a current by use of PTC characteristics, which includes a PTC element having the PTC characteristics; a pair of electrode units arranged on both sides to face each other with the PTC element being interposed therebetween; and a molding part prepared around the PTC element and the electrode units to surround at least an interface region between the PTC element and the electrode units, the molding part being made of elastic insulating material. The molding part is made of an elastic insulating material or any insulating materials selected from vacuum, gas and oil. Thus, this device may effectively restrain an arc generated while limiting overcurrent or short circuit current, and also prevent flashover between electrodes.

Description

technical field [0001] The present invention relates to a PTC (Positive Temperature Coefficient) current limiting device, and more particularly to a PTC current limiting device capable of preventing arcing between a PTC element and contact electrodes or flashover between contact electrodes. Background technique [0002] Generally, circuit breakers are widely used to prevent short circuits in high or low voltage systems. The commonly used current frequency is 60Hz, and one phase thereof can be changed to 16.7ms. If this phase is limited to one cycle, the traditional circuit breaker takes a long time (that is, at least several cycles) to break the circuit, and does not have a current limiting function for the estimated fault current value, so the fault The ripple effect lasts for a relatively long time. In addition, without breaking the short-circuit current, it will seriously affect the surrounding electrical equipment and systems. Therefore, there is a strong need for a c...

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Problems solved by technology

[0008] Therefore, the conventional current limiting device aims to increase the contact pressure by using the extrusion structure to control the surface area of ​​the first electrode 2, 3 and the second electrode 4, 5, but cannot avoid the Arc generation caused by electron repulsion energy and time difference in resistance generated in the electric arc, and it is not easy to avoid deterioration of current limiting characteristics and flashover between electrodes due to the generated arc

[0009] In addition, the frames 6, 7 proposed in the prior art, which are made of insulating material and installed at both ends of the PTC polymer element 1, are used to obtain the insulation distance, but they cannot eliminate the gap between the PTC polymer element 1 and the first electrode. 2, 3 arc generated, and can not be expected to reduce the noise generated during the breaking operation

[0010] In view of the above reasons, the conventional current limiting device can limit the current in the low current region without noise and arc, but it cannot avoid the arc in the high current or high capacitance system, so that the arc also causes the deterioration of the PTC element and makes its life shorten

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