Circuit resistance tester knowledge

Circuit resistance tester knowledge 1, what is the contact resistance?

The loop resistance tester contact resistance is the additional resistance that occurs when the static contact and the movable contact contact each other.

2. What are the parts of the circuit breaker contact resistance?

From the dynamic and static contact parts of the contraction resistance and surface resistance of two parts.

3, loop resistance tester circuit breaker contact resistance failure reasons?

1) When the large short-circuit current is broken, the contact is burned out.

2) Due to the poor adjustment of the mechanism, the stroke may be changed. When the overtravel is severely unqualified, the contact pressure or contact area may change.

3) After the circuit breaker is commissioned and installed, it has not been put into operation for a long time, so that the surfaces of the movable and static contacts are oxidized and the surface contact resistance increases.

4) Long-term operation deforms the spring and reduces the contact pressure.

5 ) Mechanical wear caused by long-term operation of mechanical part of loop resistance tester .

6) For the low oil circuit breaker, it may also be acidic due to the failure of insulation oil and acid value, and etch the surface of the contact. Or floating impurities in the oil, due to breaking short circuit current between the moving and static contacts. Residual particulate carbonaceous, metal powders increase contact resistance.

4. What are the factors affecting the contact resistance of the loop resistance tester ?

1) Material properties: resistivity, hardness, chemical properties, mechanical strength and resistivity of metal compounds.

2) Contact form: point contact, line contact, surface contact.

3) Contact surface conditions: When the contact surface forms an oxide film (except for silver), the oxide film has a much larger resistance than the metal itself.

4) Contact pressure.

5) The roughness of the contact surface.

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