What does a relay coil and a diode do

Relays in the DC circuit, intermediate relays, and electromagnet coils will be connected in parallel at both ends of a diode, his scientific name is called "freewheeling diode", because most of these coils have a thinner wire diameter, more turns, and larger inductance, when the current in these coils changes suddenly, according to Lenz's law, it can be known that the induced current will be generated in the circle, and the direction of the induced current is always obstructing the direction of the original potential, that is to say, when the coil is suddenly de-energized, it will be ** The induced electromotive force in the opposite direction is generated inside the circle, and the peak value is very high, which can reach dozens of times of the original voltage. Such a high reverse voltage will break down the transistor (driver block) that drives the coil, so a diode opposite to the direction of the power supply will be connected in parallel at both ends of the coil to vent the induced electromotive force generated by self-induction to protect the transistor.

Most of the various types of coils in the DC circuit do not have a diode, which is to prevent the triode, thyristor or contact driving the coil from being damaged by overvoltage. Where the overvoltage comes from, it is the process of transition from live to non-charged coils of various coils, which will generate several times the overvoltage of the power supply voltage at both ends of the coil, and the voltage is added to the aforementioned driving components, which may cause damage. The diodes connected in parallel provide a release path for the overvoltage, thus effectively protecting the other components.

If it is an ordinary relay, such as a power relay, or a voltage relay, then V1 and V2 are in opposite directions. The diode on the reverse parallel ** ring is called a freewheeling diode, which plays the role of suppressing the absorption of reverse electromotive force. If it is a current relay, then V1 and V2 play the role of overcurrent protection to prevent the coil from heating and burning under the condition of high current.

v3 is reverse protection.

If HBJ is a normal relay.

bai, such as power relay du

Electrical appliances, zhi

If your circuit diagram is correct and you specify the current direction, then V1+V2 and HBJ are connected in parallel to play the role of voltage clamping, limiting the working voltage to V1+V2, and V3 plays a protective role in preventing the power supply from being reversed.

In layman's terms, relay power when you don't have a parallel diode.

The spark of the device contact is large, and the spark of the relay contact is very small when you connect the diode tube, which can be weighed to extend the service life of the relay contact. The diode does not work when it is reversed, and there is a possibility that the power supply will be burned out. Correct connection, the positive pole of the diode is connected to the negative pole of the relay coil, and the negative pole of the diode is connected to the positive pole of the relay coil.

The function of these three diodes is to protect the circuit, when the relay is powered off, the induced electromotive force at both ends of the relay coil is consistent with the direction of the power supply, which can be prevented from backloading the power supply circuit by V3, and the induced electromotive force is short-circuited by V1 and V2 ......

V1 and V2 are to eliminate the induced electromotive force generated within the relay coil.

V3 should be oriented so that the relay does not work when the common power is reversed.

This is a current relay, usually we are talking about a voltage relay, the current relay is in string in the circuit, and the voltage relay is at both ends of the power supply.

A diode is connected in parallel at both ends of the relay coil, which is correctly called an "inverting" diode, which of course is used to protect the driving triode from being broken down by the back EMF of the inductor.

A diode is connected in parallel at both ends of the relay coil, which is correctly called an "inverting" diode, which of course is used to protect the driving triode from being broken down by the back EMF of the inductor.

However, in the switching power supply, it is not a simple protection role, in the switching power supply, the diode is also used to improve the efficiency of the power supply, mainly the back electromotive force as the secondary power supply, and the secondary negative voltage output is more effective.

However, in the switching power supply, it is not a simple protection role, in the switching power supply, the diode is also used to improve the efficiency of the power supply, mainly the back electromotive force as the secondary power supply, and the secondary negative voltage output is more effective.

In the design of some more efficient switching power supplies, this diode is replaced by a MOSFET and a delay control circuit is designed to accurately release the back EMF to improve efficiency.

In the design of some more efficient switching power supplies, this diode is replaced by a MOSFET and a delay control circuit is designed to accurately release the back EMF to improve efficiency.

1. When the relay is to be connected to the diode in parallel, the relay is generally connected to the PLC output terminal, because the PLC output is terminated with an inductive load.

Such as relays, solenoid valves), a resistor-capacitance loop or diode should be connected in parallel at both ends of the inductive load to play a restraining role. Prevent the coil from damaging the driver by the induced potential when the bending source Zhengtong is de-energized.

or other elements.

2. To prevent the reverse EMF generated when the DC relay is disconnected from affecting the circuit or damaging the components, the reverse parallel diode is buried in order to disturb the circuit with the back EMF crack. This diode is called a freewheeling diode.

Or an absorption diode. Generally, when we connect the circuit, the coil and switch of the relay are connected separately (that is, they are connected to different branches). We can simply use a triode.

to control the turn-on of the coil (of course, others are also possible).

Diodes are used to prevent reflow from cracking, for example.

When you flush the battery and flush the battery, there is a sudden power outage at home, and the electricity from your battery will not flow at this time.

The transistor is to amplify the current, your stereo has, the current coming out of the VCD is very small and cannot bring the speaker, and the headphones are enough. At this time, if you want to add a power supply to the speaker, you have to use a triode.

The intermediate relay makes up for the lack of contact capacity of the relay such as the source and the empty electrical appliance.

If it's a normal relay, for example:

Power relays.

Or. Voltage relays.

Freewheeling diodes.

Plays a role in inhibiting absorption reverse.

Electromotive force. role. If yes.

Current relays.

Then v1, v2 play.

Overcurrent protection. The function of the coil is to prevent the coil from being burned in the case of high current. v3 is reverse protection.

If your volt-volt circuit diagram is correct, and you specify the current direction in the absence of this round, then V1+V2 and HBJ are connected in parallel to play the role of voltage clamping, limiting the working voltage to V1+V2, and V3 plays a protective role in preventing the power supply from being reversed. Pachang.