Thermal Behavior of Electrical Contact for Different AC Loads

The supply of electrical energy to industrial, civil and laboratory equipment and installations takes place by means of contacts and conductors on which a part of the transmitted power is dissipated by thermal effect. Especially on the connection surfaces between the conductors and the loads they feed, such as sockets, contacts, switches, the power dissipated by the thermal effect can have dangerous values. Therefore, the present paper aims to study the data obtained through in-situ measurements in the electrotechnical laboratory on the heating of several types of contacts through which electrical loads are supplied in the laboratory. The measurements were carried out with a high-accuracy thermal imaging camera that determined the thermal behavior of the contacts and conductors at different distances from the connection terminals of the conductor with the electrical loads fed through that conductor. An increase in the temperature of the contacts was found both near the connection. Moreover, this increase depends also on the values of the power absorbed by the load. The change of the temperature of the conductors used in the laboratory was small, not being noticed by the thermal imaging camera. The results of the measurements were then used to develop mathematical models of the dependence of the temperature of the contacts depending on time and depending on the type of load. These models are useful for optimal choice of types of conductors and of different types of connections between the conductors and the load. The measured (real) data and numerical models obtained can also be used in the design of industrial and civil electrical installations.