Power Capacitor

What is a Power Capacitor?
Power capacitors, capacitors used in power systems and electrical equipment. Any two metal conductors separated by an insulating medium form a capacitor. The size of the capacitance of the capacitor is determined by its geometric size and the characteristics of the insulating medium between the two plates. When the capacitor is used under AC voltage, its reactive power is often used to represent the capacity of the capacitor, and the unit is var or kvar.

Classification of Power Capacitors
Power capacitors can be divided into 8 types according to their uses:
① Connect capacitors in parallel. Formerly known as phase shift capacitor. It is mainly used to compensate the reactive power of the inductive load in the power system to improve the power factor, improve the voltage quality and reduce the line loss.
② Series capacitors. Connected in series in power frequency high voltage transmission and distribution lines. It is used to compensate the distributed inductive reactance of the line and improve the static and dynamic stability of the system. Improve the voltage quality of the line, lengthen the power transmission distance and increase the transmission capacity.
③ Coupling capacitor. It is mainly used for high-frequency communication, measurement, control, protection of high-voltage power lines and as a component in devices for extracting electric energy.
④ Breaker capacitor. Originally known as voltage equalizing capacitor. Parallel connection plays a pressure equalizing role on the fracture of the ultra-high voltage circuit breaker. Make the voltage between each fracture even during the breaking process and when breaking, and can improve the arc extinguishing characteristics of the circuit breaker and increase the breaking capacity.
⑤ Heating capacitor. It is used in electric heating equipment systems with a frequency of 40-24000 Hz to improve the power factor and improve the characteristics of the circuit voltage or frequency.
⑥ Pulse capacitor. It mainly plays the role of energy storage and is used as basic energy storage components such as impulse voltage generator, impulse current generator, and oscillation circuit for circuit breaker test.
⑦ DC and filter capacitors. It is used in high-voltage DC devices and high-voltage rectification and filtering devices.
⑧ Standard capacitor. Used in power frequency high voltage measurement dielectric loss circuit, as a standard capacitor or as a capacitive voltage divider for measuring high voltage.
In the power system, there are high-voltage power capacitors (above 6KV) and low-voltage power capacitors (400V). Low-voltage power capacitors are divided into oil-immersed paper power capacitors and self-healing power capacitors according to their properties. According to the function, it can be divided into ordinary power capacitors and intelligent power capacitors.

The role of power capacitors
1. The function of series capacitors: series capacitors are connected in series in the line, and their functions are as follows:
(1) Increase the voltage at the end of the line. The capacitor connected in series in the line uses its capacitive reactance xc to compensate the inductive reactance xl of the line, so that the voltage drop of the line is reduced, thereby increasing the voltage at the end of the line (receiving end). Generally, the voltage at the end of the line can be increased by 10% to 20%.
(2) Reduce voltage fluctuations at the receiving end. When the power receiving end of the line has a greatly changing impact load (such as electric arc furnace, electric welding machine, electric track, etc.), the series capacitor can eliminate the sharp fluctuation of voltage. This is because the compensating effect of the series capacitor on the voltage drop in the line varies with the load across the capacitor. It has the performance of instantaneous adjustment with the change of load, and can automatically maintain the voltage value of the load end (power receiving end).
(3) Improve the power transmission capacity of the line. Since the compensation reactance xc of the capacitor is connected in series in the line, the voltage drop and power loss of the line are reduced, and the transmission capacity of the line is increased correspondingly.
(4) The power flow distribution of the system has been improved. Some capacitors are connected in series on some lines in the closed network, which partially changes the line reactance, so that the current flows according to the specified line, so as to achieve the purpose of power economic distribution.
(5) Improve the stability of the system. After the line is connected with capacitors in series, the power transmission capacity of the line is improved, which in itself improves the static stability of the system. When the line fault is partially removed (for example, the double circuit is cut off once, but the single-phase grounding of the circuit is cut off one phase), the equivalent reactance of the system increases sharply. At this time, the series capacitors are forcibly compensated, that is, the number of capacitors connected in series and in parallel is forcibly changed in a short time, and the capacitive reactance xc is temporarily increased to reduce the total equivalent reactance of the system. The limit power delivered (Pmax=U1U2/xl-xc) is increased, thereby improving the dynamic stability of the system.

2. The role of parallel capacitors
The shunt capacitor is connected in parallel on the bus of the system, similar to a capacitive load on the system bus, which absorbs the capacitive reactive power of the system, which is equivalent to sending inductive reactive power to the system from the shunt capacitor. Therefore, the shunt capacitor can provide inductive reactive power to the system, improve the power factor of the system operation, and increase the voltage level of the busbar at the receiving end. At the same time, it reduces the transmission of inductive reactive power on the line, reduces voltage and power loss, and thus improves the transmission capacity of the line.

Low-voltage self-healing shunt capacitors, specifications 2-60kvar, suitable for 230-690V, life > 160000h. The interior is filled with German self-healing metallic polypropylene film, which is highly resistant to pulses and voltage peaks. A small voltage breakdown usually occurs and has no effect on the operation of the capacitor. Aluminum housing, and junction box (IP20). For better heat transfer, there are 3 separate coils inside the housing. They have a pressure sensitive interrupter that disconnects the capacitors from the grid in the event of a fault. Capacitors are produced according to EN 60831 standards, and have passed RoSH, CE, ISO, UL 810 certification (10.000AFC) and West High Institute authoritative certification. HDA-LC series power capacitors are designed for low-voltage reactive power compensation systems. Applied to: motor, transformer and other fixed power factor compensation, power factor correction, tuning capacitor bank and pure capacitor bank, etc. 1. Craft Self-healing power capacitors are welded between three separate windings. The use of independent windings can reduce losses, withstand surge current impacts, and release heat in time. Vacuum potting discharges air and moisture from the inside of the capacitor. Avoid electrode oxidation and partial discharge to ensure the stability and long service life of the capacitor. The inside of the capacitor can be connected in a delta or star connection (there is no special requirement for a delta connection), and the HDA-LC low-voltage self-healing shunt capacitor can be filled with environmentally friendly gas (nitrogen). 2. Security All capacitors are installed with overvoltage separation protection devices. When a large number of electrical breakdowns occur inside the capacitor, gas is generated to cause the air pressure in the aluminum shell to rise rapidly, causing the top cover to expand and the concave edge to stretch. When a certain limit is reached, the internal connecting wires are separated. The capacitor and the grid are disconnected accordingly (in order to ensure overvoltage separation, the aluminum cover and terminals at the upper end of the capacitor must not be blocked). 3. Self-healing When the capacitor is overheated, overloaded, etc., the polypropylene film will be broken down to form an insulating area without a metallization layer. At this time, the capacitor self-healing function starts to work, and the capacitor can continue to work after self-healing, and the attenuation is negligible. 4. Discharge   HDA-LC series power capacitors are equipped with discharge resistors, and the power capacitor discharges to less than 75V within 3 minutes. 5. Connecting terminal   The terminals are designed as two-way three-hole installation (IP 20). Two pairs of opposite terminals are connected, and multi-strand copper core cables can be connected in a single hole, and the cross-section of the cable does not exceed 25mm².

Anti-harmonic power capacitor CKKB anti-harmonic power capacitors are mainly used to improve power factor and improve power quality. It is designed for the situation that the harmonic content of the power network is high and the conventional capacitor cannot operate normally. The optimized design of special polypropylene film, dielectric coating and built-in pressure explosion-proof device are used to improve the performance of the capacitor itself. Resist the influence of harmonics on capacitors, through special design, it can operate continuously in the occasion of harmonic current distortion rate (THDI) 30%~130%. Special over-current design ensures no overload under filtering conditions. 3 models to meet the needs of different occasions, built-in pressure explosion-proof device, safe and stable, green and environmentally friendly, special requirements can be customized, so that you can purchase worry-free!