10 relay principles explained

Update:31-05-2019
Summary:

1. Signal relay The signal relay is a commonly used dev […]

1. Signal relay
The signal relay is a commonly used device in the automatic control system. It is generally used to turn the circuit on and off. It releases the control command and reflects the status of the device by dropping the card. After the device returns to normal, the signal is released by the reset signal card. Important originals for automatic control and remote control circuits.
2. Electromagnetic relay
A single-phase relay that produces a predetermined response by the relative motion of mechanical components under the action of current in the input circuit. It includes DC electromagnetic relay, AC electromagnetic relay, magnetic holding relay, polarization relay, reed relay, energy-saving power relay.
3. Magnetic holding relay
The magnetic holding relay adopts the principle of energization to generate a magnetic field, that is, a "normally open, normally closed" contact, a static contact that is in an open state when the relay coil is not energized, and is called a "normally open contact"; The contact is called a "normally closed contact", and the principle that the magnetic holding relay developed so far can work is the same.
4. Solid state relay
A relay in which the input and output functions are completed by electronic components without mechanical moving parts.
5. Time relay
When the input signal is added or removed, the output part needs to be delayed or time-limited until the specified time to close or open the relay of its controlled line. A relay is an electrical control device that is an electrical device that causes a predetermined step change in the controlled output quantity in the electrical output circuit when the change in the input amount (excitation amount) reaches the specified requirement. It has an interaction between the control system (also known as the input loop) and the controlled system (also known as the output loop).
6. Temperature relay
A relay that operates when the outside temperature reaches a specified value. The most used relays are still in the industrial field, such as current digital display, voltage digital display, grating digital display, pressure digital display, inverter speed digital display, sensor digital display, frequency digital display, etc. Its role is mainly to monitor the role of notification.
7. Power relay
A power relay is a device that can make a transition in one or more electrical output circuits when the input (or excitation) meets certain specified conditions. It can be used in a neutral point direct grounding system as a directional component for zero sequence current protection. When selecting the power relay, the analysis and research can be carried out item by item according to the following points: shape and installation method; input parameters; output parameters; environmental conditions; electromagnetic compatibility; installation and use requirements.
8. Wind speed relay
When the speed of the wind reaches a certain value, the controlled circuit will be turned on or off.
9. Acceleration relay
When the acceleration of the moving object reaches the specified value, the controlled circuit will be turned on or off.
10. Safety relay
The safety relay can control the current. In order to facilitate the construction of the safety circuit, the safety relay and other components are combined, and the basic emergency stop circuit and the safety circuit are called the safety relay module.