Cable Heating at Screw Terminal– We can avoid the heating at the screw terminals by properly tightening all the screw terminals. In this article, we will discuss the reasons of looseness of electrical connections at the screw terminals & its remedial measures.
What is Screw Terminal?
A screw terminal holds a wire by tightening of screw. It is a type of electrical connection.
A wire is made in the form of a hook as shown in the above figure. The hook bends surrounding the screw terminal. The direction of hook is also important for proper connection. The wire end must be well prepared to have a good contact between the wire and screw terminal. The lesser the contact resistance, the lesser is the heating at the screw terminal.
How does heating occurs at the screw terminals?
The screw terminal holds an electrical wire & it provides connection to electrical equipment. There are wide applications of the terminals in electrical circuitry for making the electrical connections. Thus, the screw terminals are very important, and it plays a vital role in reliability of the electrical system.
The tightness of the wire in the screw terminal is very important. The looseness of connection creates resistance. When current flows through the connection point, heat loss I2R takes place if connection point has loose connection. Thus, the looseness in connection increase the contact resistance at screw terminal.
The heat generated at one point also heats up the other connection point. The resistance of the connection point increase with an increase in the temperature. Therefore, all the connections at the screw terminals must be tight.
How to reduce cable heating at Screw Terminal?
The followings are ways to reduce the cable heating at screw terminal.
- While making the cable termination at screw terminal, the wire end must be well round. The hook of the wire must cover the most of the contact area of the screw terminal.
- The wire must have good tightness in the screw terminal to have minimum contact resistance.
- The screw terminal must have proper ingress protection to avoid entry of dust, dirt and moisture. The reliability of connection deteriorates with rust and moisture.
- Periodic maintenance of the connector- cleaning, connection tightening etc.
- The selection of screw terminal according to application is paramount for better design of electrical system. For example, for vibration rich environment, the screw terminal should be robust to sustain vibrations.