Control elements you should know

When we talk about the most important control elements, and are widely used in remote control, telemetry, communication, automatic control, mechatronics and power electronic equipment, you must have guessed-relay. That's right, this is an automatic switching element with isolation function, that is, an "automatic switch" that uses a small current to control the operation of a large current. Therefore, it plays the role of automatic adjustment, safety protection and conversion circuit in the circuit.

Familiar with the main technical parameters of the relay:

1. Rated working voltage: the voltage required by the coil during normal operation

2. DC resistance: The DC resistance of the coil can be measured by a multimeter

3. Pull-in current: the relay can generate the current for pull-in action

4. Release current: the maximum current that the relay generates release action

5. Contact switching voltage and current: the voltage and current allowed by the relay, it determines the size of the voltage and current that the relay can control

Familiar with the second, the contact form of the relay:

1. Normally open (type A): the two contacts are open when the coil is not energized, and the two contacts are closed after energization

2. Normally closed (type B): the two contacts are closed when the coil is not energized, and the two contacts are disconnected after energization

3. Conversion (C-type): This contact group has 3 contacts, that is, a moving contact in the middle and a static contact at the top and bottom. When the coil is not energized, the moving contact and one of the static contacts are opened, and the other is closed; after the coil is energized, the moving contact moves, so that the original open is closed, and the original closed is open, reaching The purpose of conversion.

Familiar with three. Test items of relay performance parameters:

1. Test items without load current, such as operating value, contact resistance, mechanical life

2. Test items with load current, such as contact voltage, overload capacity, electrical life

What I recommend you to know this time is a new type of electromagnetic relay-magnetic holding relay. When it comes to magnetic holding relays, you have to boast of its superior performance characteristics than ordinary electromagnetic relays:

1. Power saving: This is because it is a bistable relay. When the contact of the relay needs to be opened or closed, only the positive (reverse) DC pulse voltage is needed to excite the coil, and the relay is completed in an instant. State transition. Usually, when the contact is in the holding state, the coil does not need to continue to be energized, and the state of the relay can be maintained only by the magnetic force of the permanent magnet.

2. Stable performance: The normally closed or normally open state of the magnetic holding relay is completely dependent on the role of the permanent magnetic steel, and the switching state is completed by the pulse electrical signal of a certain width, so the performance is stable.

3. Small size: the longest side of the general magnetic holding relay does not exceed 50mm.

4. Large load-carrying capacity: the contact switching current of the current magnetic holding relay can reach a maximum of 150A.