Why do I need capacitive discharge in power electronics?

It's not the power, it's the high-voltage device that needs to discharge the capacitor. Not only capacitors, but also more complex circuits need to be discharged due to the existence of distribution parameters.

Capacitors store a large amount of charge at high voltages, which can cause accidents if people or devices come into contact with them. So for the sake of safety. High-voltage equipment needs to be discharged after the power is off.

1. High-voltage capacitor discharge method:

Unplug the electrical appliance first; A 200,000 ohm, 2 watt resistor is used.

Connect the probe of the resistor with the terminal of the capacitor to discharge the capacitor; If the capacitor has three binding posts, connect the resistor to one of the outer and ** posts, and then connect the remaining outer and ** posts.

2. Low-voltage capacitor discharge method:

with a multimeter. The resistance level discharge. If the capacity is large, use 100k, 200k and other large gears to connect the capacitor to discharge, you will see that the number or pointer has been declining until 0, and it will generally only take a few seconds to discharge, and the meter pen will be disconnected immediately after the discharge is completed, otherwise it will be reversed charging; The small capacity can be used in 10k and 20k gears, and the discharge speed is faster.

Now high-voltage capacitors basically have built-in discharge resistance, when assembling a complete set of devices, they will generally be equipped with discharge coils, which are also used for discharge and open triangle protection, when the capacitor exits maintenance, it is also necessary to use the grounding rod to carry out effective discharge, which is the minimum safety guarantee, I hope the above answer can solve your questions.

After turning off the power supply, the wire post on the capacitor is directly short-circuited with a wire, and the discharge is clean with a snap.

If the high-voltage and large-capacity capacitor can only be discharged slowly with a resistor, or discharged with a 100W incandescent lamp and electric furnace wire, it is also OK in water (but it is not recommended, if the energy is too large, it will make the water **), remember, you must not directly short-circuit discharge, otherwise the instantaneous energy is infinite, the spark is quite dazzling, and the sound is as loud as a cannonball, hehe, not to scare you, I have tried, it will scare people, and life is in danger.

Step 1: Unplug the refrigerator or freezer.

2 3 Step 2: In order to access the capacitor, place the service panel covering the rear of the device (or the front of the device, under the door of the box).

Remove, the disassembly process will be explained in detail later. The capacitor is located in a housing above the motor compressor unit and looks like a large dry cell battery.

3 3 Step 3: To discharge the capacitor, use a 20,000 ohm, 2 watt resistor, which is available at most electronics stores and is very cheap. Connect the probe of the resistor with the terminal of the capacitor to discharge the capacitor;

If the capacitor has three binding posts, connect the resistor to one of the outer and ** posts, and then connect the remaining outer and ** posts. After the capacitor has been discharged, you are ready to make repairs.

At initial power-up, the capacitor C1 is charged by the 10K resistor R1, and the C1 potential slowly rises from low to VCC and stabilizes.

When the power is off, the potential of C1 is close to VCC, and it discharges through the VCC power supply of the IC in the second way. One is through R1 discharge, the other is through the diode rapid discharge, if there is no D1, C1 can only be slowly discharged to the VCC power supply end of the IC through the 10K resistor, so with the presence of D1, the discharge speed is much faster than the charging speed.

Capacitor discharge: As long as the capacitor touches the positive and negative, it can be discharged.

There is a short circuit discharge can also be load discharge, load discharge is relatively safe, but depending on the actual situation.

The four wires are the leads for washing and spinning the motor, respectively.

Under normal conditions, it can be directly short-circuited and discharged. Then use the multimeter to measure the charge and discharge at 1k gear.

Take the metal part of a screwdriver or tweezer and connect its two feet.

According to the capacitor working voltage, the two poles of the capacitor are shorted with a resistor. The positive and negative charges on the board will be neutralized by the resistor, which is called capacitive discharge.

The two poles of the capacitor respectively carry a certain amount of charge, and the outside and the capacitor form a closed loop, and the two poles of the capacitor form an electric field in the closed loop in order to force the electrostatic equilibrium to be formed, and the electric field continuously pushes the excess negative charge of one pole of the capacitor, and the current is formed when it is close to the positive pole of the capacitor, and the discharge begins.

The charge at both ends of the capacitor is neutralized, and after the neutralization is completed, ideally, the electric field at the two poles of the capacitor disappears, but in reality there is resistance in the closed loop, so that the amount of charge at both ends of the capacitor is exponentially neutralized, all the way to zero, but not to zero. When the capacitor is discharged, the positive charge moves from the positive plate of the capacitor to the load, and the negative charge moves from the negative plate of the capacitor to the load, and the voltage between the plates of the capacitor decreases as the charge decreases.

1. High-voltage capacitor discharge method:

Unplug the electrical appliance first; Use a 200,000 ohm, 2 watt resistor, connect the probe of the resistor with the terminal of the capacitor to discharge the capacitor; If the capacitor has three binding posts, connect the resistor to one of the outer and ** posts, and then connect the remaining outer and ** posts.

2. Low-voltage capacitor discharge method:

Discharge with the resistance level of the multimeter. If the capacity is large, use 100k, 200k and other large gears to connect the capacitor to discharge, you will see that the number or pointer has been declining until 0, and it will generally only take a few seconds to discharge, and the meter pen will be disconnected immediately after the discharge is completed, otherwise it will be reversed charging; The small capacity can be used in 10k and 20k gears, and the discharge speed is faster.

The capacitor is interrupted in the energized circuit, the capacitor stores a certain amount of voltage, and it will be discharged slowly when there are other loads or components in the circuit, or it can be quickly discharged by artificially using a small resistance or short circuit of the wire (at low voltage).

What is the principle of capacitance? How to wiring?

The capacitor is composed of an insulating material (dielectric) sandwiched between two metal plate electrodes. When a certain voltage is added to the two electrodes, an electric field will be generated in the middle of the two metal plate electrodes, and under the action of the electric field, the electrons of the insulating material (dielectric) sandwiched in the middle are pulled to the part close to the positive electrode plate to form a lasting electric field, and this process is to charge the capacitor; After the voltage added to the two electrodes disappears, the electrons are subjected to the dual action of the nucleus and the electric field force, and there will be a tendency to return to the original position, when the external circuit is turned on, the electrons return to the other electrode plate through the external circuit under the action of the internal electric field force, this process is called discharge.

The capacitor can be left as needed, under normal circumstances, each plate only leads one wire, so the general capacitor is two pins.

The 3-pin or 4-pin capacitors you are talking about are generally double capacitors (two capacitors together, the inside of the 3 pins is in series, and the two independent capacitors of the 4 pins), and the upper capacitance is generally marked 2 000 F.

Capacitor discharge: Correct operation method.

How to discharge the capacitor, generally the high-voltage capacitor is discharged with a resistor, and the low-voltage capacitor is directly discharged with a short circuit.

Rapid discharge by short circuit with artificially small resistor or wire (at low voltage). The positive and negative electrodes collide, and that's it.

The current is large instantaneously, and then slowly decreases. When there is only a capacitor, it is DC. It cannot be connected directly to the diode, and it is short-circuited.

The positive and negative electrodes collide, and that's it. Note that if the capacitor withstand voltage and the UF are too large, there will be a very loud sound when the positive and negative electrodes collide, it is best to get a light bulb or tungsten wire or something to discharge, safe.

If the capacitor is to be discharged, the two poles of the capacitor respectively carry a certain amount of charge, and the outside world and the capacitor form a closed loop (the power supply is not included in the general closed loop), the two poles of the capacitor form an electric field in the closed loop in order to force themselves to achieve electrostatic equilibrium, and the electric field continuously pushes the excess electrons (negative charge) of one pole of the capacitor to approach the positive pole of the capacitor to form a current, so that the charge at both ends of the capacitor is neutralized, and the electric field at the two poles of the capacitor disappears when the neutralization is completed, but this is in an ideal situation, and there is always resistance in the closed loop in reality. Therefore, the amount of charge at both ends of the capacitor is exponentially neutral and always tends to zero, but not zero.

Capacitors don't just charge and discharge.

1 Capacitors can be separated by cross-cutting and straight, so they are often used as coupling signals. 2Capacitance can be compensated with inductance for signal selection. 3. The charge and discharge characteristics of the capacitor can be used to filter and channel AC signals.

So a lot of capacitors are used in the circuit. Almost comparable to resistance.

Capacitors are not only used for charging and discharging.

Charging, discharging, filtering, isolation, bypass, coupling, anti-interference, integration with resistance, ......... with inductor oscillation

Capacitors don't just charge and discharge, they do other things. For example, "AC on, DC resistance", filtering, step-down, building oscillators, etc., let's take a good look.

Capacitors have two functions, one is charge and discharge, and the other is the direct and cross-current effect. Sometimes you need to be AC in the circuit! aqui te amo。

The function is to charge and discharge, but for different frequencies, the capacitance is different, and for AC and DC it is equivalent to the switching nature, and the functions are more diverse.

That's how many capacitors are used.

Summary. The capacitor is discharged and there is no electrical energy at all, the electrical energy is 0, which does not need to be calculated.

Excuse me, how to calculate the electric energy of a capacitor after discharge?

The capacitor is discharged and there is no electrical energy at all, the electrical energy is 0, which does not need to be calculated.

After charging, the stored electrical energy is released.

If it is not fully adapted, the remaining energy is calculated as e=.

Then use this formula and you're done.

For example, if a 1000 F capacitor is charged to 220V DC, the energy storage of the capacitor is: Farah 220 volts = joules nanometers.

Is this a public test?

Yes. It's the formula.

What about the energy stored in the battery?

The battery can be regarded as a capacitor, but it is much more difficult, the battery has a capacity, such as 80 ampere-hour 6V, which means that according to the 80 ampere current, under the voltage of 6V, discharge for one hour. Isn't the energy coming out of Lu He? There is no need to calculate according to the capacitance capacity.

p=ui，w=uit。

480 Wh.

MJ. Okay, got it, thanks. You're welcome.