What is a capacitive load?

Capacitive load: Compared with the power supply, the load current leads the load voltage by a phase difference. At this time, the load is a capacitive load (such as a compensated capacitor load).

A load like a capacitor in a circuit can cause the current to lead the voltage and reduce the circuit power factor.

Generally, a load with capacitance parameters, that is, a load that meets the voltage lag current characteristic, is called a capacitive load. During charging and discharging, the voltage cannot change suddenly. Its corresponding power factor is a negative value. The corresponding power factor of an inductive load is a positive value.

In the high frequency field, it refers to a load whose imaginary part is negative.

A load similar to a capacitor in a circuit can make the load current lead the load voltage by a phase difference (compared with the power supply), reducing the circuit power factor.
Generally, a load with capacitance parameters, that is, a load that meets the voltage lag current characteristics, is called a capacitive load. During charging and discharging, the voltage cannot change suddenly.

The corresponding power factor is negative, and the corresponding power factor of the inductive load is positive.

For general power control products, if the load is not specified, the apparent power is given; that is, the total capacity power; it includes both active power and reactive power;
and the general inductive load description often gives the size of active power, such as fluorescent lamps, fluorescent lamps marked as 15~40 watts, the ballast power consumption is about 8 watts, and when considering using a timer and an inductive switch to control it, these 8 watts should be added; the size of the
inductive part of different products, that is, the size of the reactive power, can be calculated by the power factor given.
In a hybrid circuit, the capacitive reactance is larger than the inductive reactance, and the circuit is capacitive and the opposite is inductive.
There are no pure inductive loads and pure capacitive loads in common electrical appliances. Because these two loads do not do useful work.
Pure inductive loads or pure capacitive loads are only used in compensation circuits. And because most loads are inductive loads except resistive loads, most of them are compensated with capacitors, so pure capacitive loads are used more than pure inductive loads. Such as motors, transformers, etc., are usually inductive loads. Some fluorescent lamps are capacitive loads.

For example:
Pure inductive load is a group of inductors. It is usually used to compensate for the capacitive current in the circuit.
The coil part of the electrical equipment with coils in the circuit is a pure inductive load. Such as motors, transformers, electric fans, fluorescent lamp ballasts, etc.

The current of a pure inductive load cannot change suddenly. Inductive loads are widely used. The capacitive part of an electrical device with capacitance in a circuit is a pure capacitive load. Such as compensation capacitors.
The voltage of a pure inductive load cannot change suddenly. Theoretically, pure resistance circuits, pure capacitance circuits, and pure inductance circuits do not exist.
When a resistance load is working, there will also be inductance and capacitance loads. For example, there will be capacitance between the wires, and there will be inductance between the wires and the ground. During this period, the inductive load is usually greater than the capacitive load. Power capacitors will also generate heat when working, that is, resistive work. The same is true for inductance. The impedance of a component is a function of frequency. In the full frequency range, pure resistance circuits, pure capacitance circuits, and pure inductance circuits do not exist.
In theory, they can only exist at a certain frequency. In practice, it should not be possible.
1. Harmonics: The frequency of China's power grid is 50Hz, and any wave with a frequency higher than 50Hz is called a harmonic. Harmonics are generated in the form of doubling, that is, the frequency is a multiple of 50: 100, 150, 200..., and any wave higher than 50Hz is called a high harmonic.
2. Load: refers to a device that consumes electrical energy and converts electrical energy into mechanical energy, heat energy, light energy, etc. Load refers to electrical appliances, such as: lights, lamps, electric furnaces, motors, refrigerators, air conditioners, etc.
3. Light load: Light load mainly refers to the equipment driven by the motor is relatively light and does not reach its designed rated power, that is, the actual load is less than the designed load.
4. Variable load: Variable load means that the load driven by the motor is constantly changing during operation, sometimes heavy, sometimes light, and the motor is reflected in the output power of the motor is sometimes large, sometimes small. Under the condition of constant voltage, the current changes with the load. For example: jaw crusher, various presses, stamping machine tools, pumping units, compressors, hydraulic presses, electric sewing machines, etc.
5. Constant load: Constant load is also called fixed load, which means that the load of the motor is basically unchanged during operation, and the output power and current of the motor are basically a constant value. Light load may be constant load.
6. Overload operation: Overload operation means that the motor is in a state of operation that exceeds its own load capacity. For example, a 55KW motor has a rated current of 110A, and in actual operation the current exceeds 110A, which is overload operation. Equipment that is in overload operation for a long time will be damaged and its service life will be reduced.
7. Load rate: The load rate is the ratio of the actual working current to the rated current. Load rate = actual working current ÷ rated current × 100%
8. The relationship between the rated power and rated current of the motor: Generally speaking, the rated current of the motor is twice the rated power.
For example: a 37KW motor has a rated current of approximately 37*2=74A.
A 100KW motor has a rated current of approximately 100*2=200A.
9. Inductive load, resistive load: For lamps, lamps that emit light by gas conduction are inductive loads, and lamps that emit light by resistance wire are resistive loads. Inductive loads include: fluorescent lamps, high-pressure sodium lamps, mercury lamps, metal halide lamps, etc. Resistive loads include: iodine tungsten lamps, incandescent lamps, resistance furnaces, ovens, electric water heaters, oil heaters, etc. Motors are also inductive loads.
10. Actual working currents of several commonly used lights: (under the condition of 220V grid voltage)
1. A single 400W high-pressure sodium lamp has a working current of 3.1 to 3.3A.
2. A single 250W high-pressure sodium lamp has a working current of 2.0 to 2.3A.
3. A single 400W metal halide lamp has a working current of 2.0 to 2.2A.
4. A single 250W metal halide lamp has a working current of 1.4 to 1.6A.
5. A single 40W fluorescent lamp with inductive ballast has a working current of 0.28 to 0.30A.
6. A single 40W fluorescent lamp with electronic ballast has a working current of 0.14 to 0.16A.
According to the above data, in addition to the light itself, the ballast also consumes electricity.
11. In the lighting circuit, if all reactance ballasts are used, the current will drop by 30% after the energy saver is installed, but the current of electronic fluorescent lamps basically does not drop. There is a compensation device in the circuit, and the current drop is relatively small.