Contact resistance refers to the resistance of current flow due to surface conditions and other reasons when the contact surfaces are in contact with each other (when the device is in a closed state). This can happen between the following contacts:

• crusher

• contact

• relay

• switch

• connector

• other switching equipment

Also known as a Ductor test, the contact resistance test is used to measure the resistance of electrical connections -- terminals, connectors, connectors, busbar or cable connections, etc. These can be any connection between two conductors, such as a cable connection or a busbar segment. The instrument used for testing air ducts is called the ohmmeter. Because its function is to test air ducts, the ohmmeter is also called the air duct tester.

Many forms of catheter tester can be found, such as micro, megohm and milliohmmeter, static resistance tester or DLRO (which stands for digital low resistance ohmmeter). Used to measure resistance in different applications of electrical testing. The tester consists of a dc ammeter and other components. This test measures the resistance at the micro or milliohm level and is mainly used to verify the correctness of the electrical connection and can detect the following problems:

• loose connection

• there is enough tension in the bolt connection

• contact surface corrosion

• the contact point is contaminated or corroded

The term contact resistance refers to the contribution to the total resistance of the system, which can be attributed to the contact interface of the electrical leads and connections, as opposed to the intrinsic resistance, which is an intrinsic characteristic and is independent of the measurement method. This effect is usually described in terms of "electrical contact resistance" or "ECR" and may change over time in a process called resistance creep, most commonly decreasing. William Shockley introduced the idea of a potential drop on the injected electrode to explain the difference between the experimental results and the model of progressive channel approximation. In addition to the term ECR, use "interface resistance," "transition resistance," or just "correction terms." The term "parasitic resistance" has been used as a more general term,