Relays are essential components in electrical and electronic circuits, providing a way to control high-power devices with a low-power signal. One of the key parameters when choosing or designing a relay is understanding its current characteristics, specifically the “relay current.” This article will delve into the concept of relay current, its types, and its importance in ensuring the proper functioning of electrical circuits.
What is Relay Current? Relay current refers to the electric current that flows through the relay’s contacts when the relay is in operation. A relay consists of a coil that, when energized, creates a magnetic field, causing the relay’s contacts to close or open, thereby controlling the flow of current in the circuit. The current passing through the contacts (the switching current) and the current flowing through the relay’s coil (the activation current) are both crucial in determining the appropriate relay for a given application. Types of Relay Currents Coil Current (Activation Current)： The coil current is the current required to activate the relay. When a voltage is applied across the relay’s coil, it creates a magnetic field that pulls the relay contacts together or apart, depending on the design. This current is typically low and is used to trigger the relay’s switching mechanism. The coil current is determined by the voltage applied and the resistance of the coil. For example, a 12V relay with a coil resistance of 100 ohms will have a coil current of approximately 120 mA (using Ohm’s law： I = V/R).