What is inverse time overcurrent relay?

What is inverse time overcurrent relay?

At this type of relay, operating time depends on the amount of drive. If the amount of drive is very high, the relay operation is very fast. In other words, the relay running time which is a relay delay is inversely proportional to the magnitude of the drive.

The general characteristics of the reversed relay are shown in the figure below.

Here, in the graph, it is clear that when the actuation quantity is OA, the operating time of the relay is OA ‘, when the actuation quantity is OB, the operation time of the relay is OB’ and when the variator is OC , the quantity is OC “.

In the previous graph, it is also observed that when the amount of disk is less than OA, the operating time of the relay becomes infinite, which means that to operate an amount less than OA, the relay is not activated. do not. This minimum value for the actuation by which a relay initiates its operation is known as the elevation value of the actuator. Here it is designated as OA.

In addition, it is observed in the graph that when the quantitative approaches are applied infinitely along the x-axis, the operating time does not approach zero. The curve approaches an approximately constant operating time. This is approximately the minimum time required for the operation of the relay.

The inverse time relay, if the inverter is current, is known as a reverse current relay. In this type of relay, the inverted time is obtained by connecting some mechanical accessories to the relay.

The reverse delay time is obtained in the induction disc relay by providing a permanent magnet so that when the disc rotates, cut the permanent magnet flow. Due to this, the current is induced in the disk, which slows down the movement of the disk. A solenoid relay can be made by an inverted time relay supplying a piston and oil drums. A piston, attached to the rolling piston in motion, is immersed in oil in a container.

When the solenoid relay is operated, the piston moves up with the iron piston. The viscosity of the oil slows the upward movement of the piston. The speed of this upward movement towards gravity also depends on the force with which the solenoid attracts the iron piston. This attraction force of the solenoid depends on the magnitude of the conduction current. Therefore, the operating time of the relay is inversely proportional to the drive current.

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