In the field of power equipment maintenance, the term "contact resistance" may sound a bit professional, but it is related to the safe and stable operation of the equipment. What is contact resistance? Why is it important? Today, let's unveil its mysterious veil together.

What is contact resistance?

Simply put, contact resistance refers to the additional resistance caused by imperfect contact surfaces when current passes between two conductors (such as the contacts of a switch or the connection of a busbar). Imagine that even the smoothest metal surface, when enlarged, will have countless tiny bumps and irregularities. The current is transmitted along these tiny "bridges", and naturally there will be obstacles, which is contact resistance.

The 'behind the scenes' driving force that affects contact resistance

Surface condition: Oxidation layer, oil stains, dust, etc. will all form an insulation layer on the contact surface, greatly increasing the contact resistance.

Contact pressure: Insufficient contact pressure results in fewer micro contact points and naturally higher resistance. Excessive pressure can sometimes cause surface deformation and affect contact.

Material factor: Different metal materials have different conductivity, and their own characteristics can also affect contact resistance.

Environmental factors such as temperature and humidity can affect the oxidation rate and contact state of metal surfaces.

The 'secret weapon' for measuring contact resistance

To accurately measure contact resistance, a specialized tool - a contact resistance tester - is required. This type of instrument can accurately measure tiny resistance values, helping us detect potential hazards in a timely manner. Wuhan UHV Power Technology Co., Ltd. has been deeply involved in the field of power testing instruments for many years. Its developed contact resistance tester enjoys a high reputation in the industry for its high precision and stability, and is a reliable assistant for power equipment testing.

Who is inseparable from contact resistance?

The measurement of contact resistance is closely related to the maintenance work of many power equipment. for example

High voltage switchgear: The contact resistance of switch contacts is a key indicator for measuring their performance and service life.

Transformer: Abnormal contact resistance at the connection points of busbars and tap changers may cause local overheating.

Generator: The contact resistance of the excitation circuit and grounding system also needs attention.

How to 'cultivate' lower contact resistance?

The key to optimizing contact resistance lies in "maintaining cleanliness" and "ensuring pressure".

Regular cleaning: According to regulations, open the equipment regularly to clean the oxide and dirt on the contact surface, using specialized cleaning agents and tools.

Check fastening: Ensure that all bolts and connectors are securely fastened in place and provide sufficient contact pressure.

Regular testing: With the help of a contact resistance tester, regular measurements are taken to promptly detect and handle any abnormalities. The professional equipment of Wuhan UHV Power Technology Co., Ltd. can help you accurately diagnose and avoid faults caused by poor contact.

Frequently Asked Questions (FAQ)

What is the measurement principle of the contact resistance tester? It is usually measured using the four wire method, by applying a constant DC current and measuring the voltage drop on both sides of the contact to calculate the resistance, effectively eliminating the interference of lead resistance and ensuring the accuracy of the measurement.

What is the qualified contact resistance value? The qualification standards vary depending on the type of equipment and voltage level, and generally require reference to the technical specifications or relevant industry standards provided by the equipment manufacturer.

Why does contact resistance change over time? Mainly caused by factors such as oxidation, wear, dust accumulation, and loose contact pressure on the contact surface.

What other methods can be used to determine poor contact besides a contact resistance tester? It can be detected through infrared thermography, and poor contact points often result in local overheating.

What are the hazards of excessive contact resistance? It can cause local overheating, accelerate insulation aging, increase line losses, and in severe cases, may lead to fire or equipment damage.