Contact Resistance Meter: What is the Need to Check Contact Resistance?

Electronic devices are everywhere today whether at home or in infrastructure. To avoid electrical damage circuit breakers, switches, relays and other electrical connections must be kept in continuous operation. However, inherent resistance exists when two conductors come into contact this demands constant maintenance. In this situation, the Contact Resistance Meter proves to be an extremely useful instrument. Let’s learn more about this key equipment!

Contact resistance 

It is the resistance to current flow caused by surface conditions and other factors when the contact surfaces come into contact (in the device's closed state). This can occur between components like disconnectors, circuit breakers, relays and switches. The contact resistance test can help you understand the line's connection quality and conductive properties, as well as prevent dangerous overheating of the contacts.

Contact Resistance Meter

The Contact Resistance Meter is generally used to test switching devices, cable junctions, and other electrical connections. It allows for the measurement of voltage dips, contact resistance, and joint or connection resistance in milli-ohms or micro-ohms.

Why Does a Contact Resistance Test Required?

It is necessary to often examine the circuit breaker's contacts to make sure everything is functioning properly. Poorly maintained or broken contacts can result in arcing, phase loss, and even fire.

This test is especially critical for connections that carry a lot of current (such as switchgear busbars) because higher contact resistance can lead to decreased current-carrying capability and higher losses. Ductor testing is often done with a micro/milli-ohmmeter or a low ohmmeter.

You can identify and prevent contact corrosion by measuring contact resistance, which also helps you identify fretting corrosion of contacts. Increased contact resistance might result in a high voltage drop in the system which must be managed. 

Contact Resistance Test on Circuit Breaker 

Visual and contact resistance checks are two frequent tests done on circuit breaker contacts.

Visual Examination

The visual examination includes inspecting the circuit breaker contacts for dents caused by arcing, as well as contact wear or deformation.

Contact Resistance Measurement

The contact resistance measurement involves passing a fixed current through the contacts and measuring the voltage drop between them. This test is performed with a specialized contact resistance measurement device. Then use Ohm's law to check out the resistance. The resistance value should be compared to the value provided by the manufacturer. This figure should also be compared to earlier data.

Both of these tests must be performed simultaneously. There have been occasions where contacts have adequate contact resistance yet are damaged. Thus to be certified healthy a contact must have a strong contact resistance and pass the visual inspection test.

The Working of the Contact Resistance Meter

The contact resistance tester works as per Ohm's law. It checks if the current in the circuit is normal or not. The meter or tester does so by measuring the resistance value of the electrical components. In addition to that, the tester connects a voltage source to the electrical component under test while also connecting an ammeter or voltmeter to the other end of the circuit. 

The tester or meter determines the overall resistance value in the circuit. It is done by measuring the internal current and voltage values of the electrical components. And the Ohm's law is applied. If the measured resistance value exceeds the permitted range it indicates a malfunction or damage in the circuit. It is now important to conduct a more thorough inspection and repair of electrical components. The contact resistance tester is useful for testing a wide range of circuits, electrical components, and systems, including generators, cables, relays, switches, and so on.

To Sum Up

Contact resistance tests indicate the health of the contacts and their capacity to handle the rated current. As mentioned earlier the maximum contact resistance should be confirmed against the manufacturer's requirements. SB Electrotech is the leading Contact Resistance Meter Suppliers in India that provide high-quality meters. Contact us for further information or to place your order!

Frequently Asked Questions

What is the role of a contact resistance test?

The circuit breaker's contacts must be checked regularly to ensure that it is healthy and functional. Poor or inadequate contact can result in arcing, phase loss and even fire. This test is especially critical for contacts that carry a lot of current, such as switchgear busbars, where increased contact resistance means poorer ampacities and higher losses. 

A micro/milliohm meter or a low ohmmeter is commonly used to conduct contact resistance measurements. Contact resistance measurements aid in the identification of fretting corrosion of contacts, as well as the diagnosis and prevention of contact corrosion. An increase in contact resistance can produce a large voltage drop in the system and must be regulated.

What is the importance of contact resistance meter testing?

Testing is crucial for contact resistance meters, and regular checks are recommended.

Routine contact resistance tests are essential, particularly for circuit breaker contacts, to guarantee appropriate functionality. Neglected or broken contacts can cause arcing, phase loss, and fires. These meters help to identify fretting corrosion and reduce power outages, heat generation, contactor capacity loss, and failure to stop power when necessary.

What is contact resistance?

Contact resistance is the resistance to current flow caused by surface conditions and other factors when contacts are nearby. This may happen between contacts of Breakers, Contactors, Relays, Switches, and Connectors. Contact resistance testing determines the resistance of electrical connections such as joints, connectors, terminations, busbar sections, and cable connections. 

What happens if your contact resistance is high?

High resistance can cause voltage dips, heating at contact sites and poor electrical performance. Materials having low contact resistance like silver or gold may be used in certain applications to increase the overall efficiency and dependability of electrical contacts.

What are the factors that influence contact resistance?

Contact material, positive pressure, surface condition, operating voltage and current all have a significant impact on circuit breakers' contact resistance. Contact resistances will differ between mating contacts with the same specification but constructed of different materials.

What's the importance of measuring contact resistance?

The measurement of contact resistance helps you in the identification of fretting corrosion of contacts and permits contact corrosion to be identified and avoided. Increased contact resistance might result in a high voltage drop in the system which must be managed. 

What is the key principle of a contact resistance meter?

The working principle of the contact resistance meter is based on Ohm’s law. It determines whether the current in a circuit is normal or not. This is done by measuring the value inside the electrical components.

What are the factors that are responsible for increased resistance?

The factors that are responsible for a boost in resistance include the type of material from which the resistor is made the thickness and length of the resistor and the temperature of the conductor.