Connecting the induction motor in a network with a single phase (220), there is a need to provide a phase shift to simulate a three-phase network. Otherwise, the motor will be unable to function because of the lack of magnetic field rotation. In this case, possible to use capacitors having the ability to create the desired bias, thereby converting the single-phase sinusoidal oscillations current into a kind of three-phase. Problem is the proper selection of capacitors. To do this, you must settle with the maximum accuracy.
Presented below is an online calculator for calculating capacity will perform all actions quite simply and quickly without making mistakes in the calculations.
Calculating the necessary indicators should be on their own to take advantage of the table.
| Motor connection method | Formula, necessary for the production of calculations |
| "Star" |
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| "Triangle" | Cp = (4800 / √3) * P / (U² * η * cosφ) |
can decipher the notation as follows:
- Cf. - capacity of working elements (uF);
- Cn - tank launchers elements;
- I - the current values (A);
- U - voltage values (V);
- η - Coefficient of efficiency of the electric motor as a percentage divided by 100;
- cosφ - Power factor.
After entering all necessary data into the appropriate fields click "calculate ...". The resulting figures are used for the selection of the vessel. The only disadvantage - it is rare to find an element with the calculated parameters. In this case we take the nearest container standing below on the indicator. If we take a more powerful element can overheat the motor windings due to the increase in operating current, which will inevitably lead to damage to the insulation and the risk of the inter-track circuit. In rare cases, the coincidence of indicators, of course, it is better to choose such.
The rated voltage of the capacitor must be at least one and a half times higher than the network. The reason for this - a sharp increase in this indicator in the starting moment. When connected to a single-phase network denomination should be 360. If phase voltage is connected via two wires - 400-450 at. But this minimum limit. In fact, professionals are advised to take even higher - no problem it does not create.
Below is a table of nominal working and the starting capacitor. For example - a series CBB60 (polypropylene film, the main purpose of which - circuit connecting asynchronous motor) and a series CBB65, placed in an aluminum housing.
To start apply to non-polar electrolytic capacitors based (CD60). As workers, they are not applicable. Their problem is that the sustained load significantly reduces their lifespan. Although as launchers and allowed CBB60 (CBB65), but they are of larger with the same tanks. The table below shows recommended for such exploitation of capacitors that can operate with electric motors.
| Polypropylene film CBB60 (Russian equivalent K78-17) and CBB65 | Electrolytic nonpolar CD60 | |
| voltage rating (in) | 400; 450; 630 | 220—275; 300; 450 |
| Capacitance (nF) | 1,5; 2,0;2,5; 3,0; 3,5; 4,0; 5,0; 6,0; 7,0; 8,0; 10; 12; 14; 15; 16; 20; 25; 30; 35; 40; 45; 50; 60; 65; 70; 75; 80; 85; 90; 100; 120; 150 | 5,0; 10; 15; 20; 25; 50; 75; 100; 150; 200; 250; 300; 350; 400; 450; 500; 600; 700; 800; 1000; 1200; 1500 |
It happens that the elements with the necessary capacity is not. Then you can "pair" two. It is understood that the parallel connection and the serial will give quite different figures. The most optimum is a serial connection. And to calculate the total capacitance offer you to use another online calculator that will save time and eliminate the unnecessary calculations.
