GDZX ZXHL-100P, Руководство пользователя

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Appendix I: Contact (loop) resistance Basics
1. What is the contact resistance?
Contact resistance is additional resistance static contact with each other when in contact with
the movable contact that appears.
2. The circuit breaker contact resistance which several parts?
Shrink resistance static contact resistance of the contact portion and the surface is composed of
two parts move.
3. The circuit breaker contact resistance reasons for failure?
a. contact burn when breaking a large short-circuit current.
b. due to poor institutional adjustment fixed is not strong, resulting in changes in itinerary, when
overstroke serious failure, caused by the contact pressure or the contact area changes.
c. After the breaker installation commissioning and long-term is not in operation, so dynamic and
static contact surface oxidation, the contact surface resistance increases.
d. long-running spring deformation, so that the contact pressure drops.
e. after long-term operation of the mechanical parts caused by mechanical wear.
f. for less oil circuit breakers, also may be due to defective insulation value oleic acidic reaction,
etching the contact surface. Or oil floating impurities, move, carbonaceous particles between the
stationary contact after breaking the short-circuit current due to the residual metal powder, the
contact resistance increases.
4.The factors affecting the contact resistance?
a.material properties: hardness, chemical properties, mechanical strength and resistivity of the
metal compound.
b.contact form: point contact, line contact, surface contact.
c.contact surface condition: When (silver exceptions) the contact surface to form an oxide film,
the oxide film resistance than the metal itself is much greater.
d.contact pressure.
e.the roughness of the contact surface.