Does contact resistance increase with temperature?
Does contact resistance increase with temperature?
An elevated temperature at the junction may also cause plastic and/or elastic deformation of the roughness asperities, especially for softer materials, with an associated increase in the actual contact area and a decrease in the contact resistance.
What is meant by contact resistance?
The term contact resistance refers to the contribution to the total resistance of a system which can be attributed to the contacting interfaces of electrical leads and connections as opposed to the intrinsic resistance.
What does high contact resistance mean?
Contact resistance is the resistance to current flow, due to surface conditions and other causes, when contacts are touching one another (in the closed condition of the device). This can occur between contacts of: Breakers. Contactors. Relays.
How does contact resistance affect heat transfer?
Causes of contact resistance: This air gap has comparatively low thermal conductivity, therefore it adds extra resistance to the flow of heat. This resistance per unit area of contacting surface is known as contact resistance.
What is contact resistance in heat transfer?
In thermal engineering, the thermal contact conductance [W/m2. K] or thermal contact resistance [m2. K/W] represents the heat conduction between two solid bodies. When components are bolted or otherwise pressed together, a knowledge of the thermal performance of such joints is also needed.
What is the value of contact resistance?
The smaller current ratings will have higher contact resistance. As a general rule-of-thumb, low-voltage circuit breakers should have contact resistances of 100 µΩ or less, while readings above 300 µΩ are an indication of trouble.
What is the main cause of thermal contact resistance?
The contact resistance depends on the surface roughness to a great extent. The pressure holding the two surfaces together also influences the contact resistance. Thermal contact resistance is observed to decrease with decreasing surface roughness and increasing interface pressure.
