Contact-resistance is defined as the resistance between the semiconductor and metallic connections. In simpler terms, it is also termed as the resistance to current flow caused by surface issues and other factors when contacts are in contact with one another.

Where does Contact Resistance occur?

Contact Resistance occurs between various things, which are mentioned below:

  • Breakers
  • Contractors
  • Relays
  • Switches
  • Connectors
  • Other Switching Devices

The diagnosis and prevention of contact corrosion are both made possible by measuring the resistance of the contacts, which aids in identifying the fretting corrosion of the contacts. A high-voltage drop in the system can be brought on by an increase in this resistance, and this needs to be managed.

What is measured with Contact Resistance?

The electrical contact resistance test is applied to different connections, such as cable junctions and switching devices. The contact resistance measure can determine the resistance provided by the contacts, the resistance of the joints, or the voltage drop. With this test, resistance at the milli- or micro-ohm level is found.

To check the condition of the contactor, and make-break contacts, the contact-resistance is measured. When it comes to joints and connections between current-carrying parts, the test can:

  • Determine any loose links.
  • Show the system’s high-voltage drop spots.
  • Bolted joints with low tension are indicated.
  • Identify damaged bus bar surfaces

Also Read: What is a Combined Collector?

Corrosion from contact is caused by the following:

  • Power outage
  • Heat production
  • Reduction in contactor capacity
  • Failing to stop the current when it should

These issues may cause connected motors to fail severely. One of the causes of contact failure that results in high contact resistance is fretting corrosion at high temperatures. Contact surfaces and contact tips are treated with various surface coatings and other methods to increase their corrosion resistance.


Elliot is a passionate environmentalist and blogger who has dedicated his life to spreading awareness about conservation, green energy, and renewable energy. With a background in environmental science, he has a deep understanding of the issues facing our planet and is committed to educating others on how they can make a difference.

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