Capacitor Basics: Power Capacitors

Table of contents:
(1) How to determine the size of the power supply capacitor
(2) What is the role of power capacitors
(3) Do capacitors consume power?
(4) How does the capacitor improve the power factor

Power capacitors are capacitors used in power systems and electrical equipment. Capacitors are very many components used in the circuit, so how to determine the size of the power supply capacitor? What does a power capacitor do? Do capacitors dissipate power? How do capacitors improve power factor?

How to determine the size of the power supply 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.

The capacitor is a very common energy storage component in the circuit. It neither generates energy nor consumes energy. We use capacitance to measure the performance of its stored charge. When we design and assemble the circuit, we need to distinguish the capacitance and The size of the capacity, so how can we identify its rated capacity?
① Direct labeling method.
The direct marking method is the direct marking method, which uses μF as the unit, R marks the position of the decimal point and directly marks the capacity value with a combination of numbers and unit symbols. For example, 3R5 indicates a capacitance of 3.5μF.

② unit symbol method.
Based on the symbol used by the unit, numbers and symbols are regularly combined to indicate its capacity. For example, p50 indicates a capacity of 0.5pF; 3n5 indicates a capacity of 3.5nF; 1u5 indicates a capacity of 1.5μF.

③ Mathematical notation.
Usually, three digits, with pF as the unit, the first and second digits are valid figures, and the third digit is its multiple. For example, 105 indicates the capacitance of 10*105pF.

④ Color circle marking method.
Similar to the marking method of the color ring resistor, the capacitance parameter is marked by the color ring/color point.

What is the role of power capacitors
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 as to reduce the voltage drop of the line, thereby increasing the voltage at the end of the line (power receiving end). Generally, the voltage at the end of the line can be increased by 10% at most ~20%.

②Reduce voltage fluctuations at the receiving end. When the power receiving end of the line has a greatly changing impact load (such as an electric arc furnace, electric welding machine, electric track, etc.), the series capacitor can eliminate the sharp fluctuation of voltage. This is because the compensation effect of the series capacitor on the voltage drop in the line changes with the load passing through the capacitor has the performance of instantaneous adjustment with the change of the 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 correspondingly increased.

Do Capacitors Dissipate Power?
The manufacturer of power capacitors replied: The power of capacitors belongs to reactive power.
The calculation method of the power of the capacitor:
①Capacitor power = voltage across the capacitor × current flowing through the capacitor
②Capacitor power = the square of the current flowing through the capacitor × the capacitive reactance of the capacitor
③Capacitor power = the square of the voltage across the capacitor ÷ the capacitive reactance of the capacitor

How do capacitors improve power factor? Do you know how to improve the power factor?
In the power system, most equipment is an inductive load, which needs to consume reactive power during operation; after installing parallel capacitors, the reactive power required by the load will be provided by the capacitor, and the proportion of reactive power provided by the generator will be reduced, and the proportion of active power will be reduced. Increased, so that the power factor of the enterprise will be improved.
Power capacitor manufacturers tell you how to improve the natural factor:
① Properly select the motor capacity, reduce the reactive power consumption of the motor, and prevent "big horses and small carts".
② For light-load motors whose average load is less than about 40% of their rated capacity, the coil can be changed to a delta connection (or automatic conversion).
③ Avoid running the motor or equipment without load.
④ Configure the transformer reasonably and choose its capacity properly.
⑤Adjust production shifts, balance electricity load and increase electricity load rate.
⑥Improve the layout of distribution lines and avoid twists and turns.

Summarize:
The above is the relevant content and information about power capacitors summarized by the manufacturer of power capacitors in the month, hoping to bring you help. If you have other questions, you can leave a message below the platform, and the editor will solve the problems for you in time. I believe that through this article, you have a certain understanding of this issue. If you want to know more, please pay more attention to Zhiyue.

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