Control relays are used in electric and electronic equipment. Transistors, motors, power plants, uninterrupted power supply systems and power meters are among the equipments where control relays are used.
A control relay is a device which opens or closes a switch in accordance with the present flow through a conducting coil. It’s an electromagnetic device and the switches do not are available in direct contact with the conducting coil. Typically, it controls the power flow in a circuit.
The control relay operates in two modes. When current flows through the electromagnetic coil it attracts a magnetic substance which closes the switch and vice versa when there isn’t any current flow through the coil. A spring will assist within the closing and opening of the switches. The relay will not go into an intermediate stage between on and off. Electronic circuits will be coupled to the relays to make them operate automatically. The switching process shall be pre-programmed in a circuit in accordance with the necessity of a selected application. Logical controllers or programmed micro controllers are used in electronic and complex controls. Ladder logic is the logic mainly utilized in relay control.
The relay operates basically by the principle of magnetization and de-magnetization. As current flows through the coil it creates magnetic poles within the coil, called the North Pole and South Pole. These poles attract an armature which will likely be coupled to a spring. As long as the present is sufficient within the coil, the armature stays interested in the coil and the switch will stay within the on condition. As the current value drops, the attractive force of the coil is overcome by the potential energy of the spring and thus the spring pulls back the armature and the switch goes on to the off position. The efficiency of the relay is measured by taking into account how briskly it might switch between the stages. Relays of very fast switching speeds can be found now.
Many factors are considered while designing relays. The conducting and magnetic properties of the coil and the nature of material of the coil are important factors. Also, the magnitude current flow should even be considered. If the present exceeds the capacity of the coil then the relay and the equipments connected to it might get damaged. Relays ought to be operated in optimal temperature conditions as it affects the life cycle of the device. Temperature should be kept below a level which the relay can tolerate.