Photocoupler

Intermediate relays are a type of electrical relay that operate on the same principle as AC contactors. They consist of a fixed iron core, a movable iron core, a spring, moving and static contacts, a coil, terminal blocks, and an outer casing. When the coil is energized, electromagnetic force causes the movable iron core to move, which opens the normally closed contact and closes the normally open contact. When the coil is de-energized, the spring returns the movable core to its original position, resetting the contacts.

1. Replacing Small Contactors: Intermediate relays can replace small contactors when the load capacity is low, such as in electric shutters or small appliances. This not only serves the control purpose but also saves space and makes the control system more compact and precise.

2. Increasing Contact Count: One of the most common uses of intermediate relays is to increase the number of available contacts. For example, if a single contactor needs to control multiple components, an intermediate relay can be added to the circuit to expand the control capability.

3. Enhancing Contact Capacity: Although the load capacity of an intermediate relay isn't very high, it still has sufficient power to handle moderate loads. Its low driving current makes it ideal for expanding contact capacity. For instance, inductive switches or transistors usually cannot directly control high-load devices, so an intermediate relay is used instead to manage these loads efficiently.

4. Changing Contact Type: In industrial control systems, there are times when a normally closed contact from a contactor is needed for control, but all of its contacts are already in use. In such cases, an intermediate relay can be connected in parallel with the contactor’s coil, allowing its normally closed contact to be used for the required control function, effectively switching the contact type.

5. Acting as a Switch: In some control circuits, intermediate relays are used to switch electrical components. Their contacts are controlled to turn devices on or off. For example, in color TVs or monitors, an intermediate relay might be used in the automatic degaussing circuit, where a transistor controls the relay's operation to manage the degaussing coil.

6. Voltage Conversion: Intermediate relays can also be used to convert voltage levels in a circuit, making them versatile for various applications.

7. Reducing Circuit Interference: These relays help minimize electrical interference by isolating different parts of a circuit, ensuring smoother and more reliable operation.