Phase shift capacitor calculation

Calculation of phase shift capacitor

Program for calculating the capacitance of the capacitor to be applied to a three-phase electric motor to obtain operation with single-phase current.

We are pleased to present you a program designed by Itieffe to simplify the calculation of the phase shift capacitor. In a world where energy efficiency and power control have become crucial aspects in electrical systems, understanding how they work and sizing them correctly is of fundamental importance.

This program was created to provide a quick and reliable solution for calculating them. It will guide you through the process, explaining how to determine the optimal size of a capacitor and improve the energy efficiency of your system.

We hope this program will become your trusted resource in the complex world of capacitor design. Whether you are engineers, technicians, designers or simply interested, we are here to help you understand, calculate and apply the foregoing in your work.

Let's start this journey together, discovering this world and its role in optimizing electricity.

Calcohol phase shift capacitor

The operation of a three-phase asynchronous motor is due to the power supply carried out with three-phase current which are out of phase with each other by 120 °

It is possible to supply the same motor with single-phase current nand cases in which the required power is not 100% (and the same does not exceed certain powers) through a phase shift capacitor

The efficiency will not be high because the phase shift obtained is not the optimal one.

However, it can be applied for various uses: electric pumps, centrifugal and helical fans, drills and for all those machines with low power and that do not require high starting currents.

The majority of cases will involve delta connection, suitable for a 220-380V three-phase motor powered with 220V single-phase.

The following figure shows the connections for three-phase asynchronous motors powered in single-phase with star and delta connection and with clockwise and anticlockwise rotation.

The capacitor produces the phase shift necessary to obtain a rotating magnetic field inside the motor

The magnitude of the phase shift is the resultant of the capacity and current involved, for this reason the phase shift can never be optimal, it varies with the load and will always be a compromise

A motor so powered will never be able to provide the rated power, with the value calculated here the power is reduced to 60-70% and is a compromise for operation with limited and medium loads

The highest starting torque for single-phase motor is obtained when the delay we get with our capacitor is 90 °

For cases in which the load is always high, it is possible to increase the capacity to obtain more power, but be careful, in this case it must not work without load or with low loads, you risk burning the engine

It is false to think that with a larger capacitor it gets more power, even a failure could develop in the user

The greatest penalty of this type of connection occurs in the starting phase, the available torque is 30-40% of that obtainable with the motor powered normally

Warnings

Remember that in this particular application the capacitor is subject to high currents and repeated polarity inversions, if it is not suitable for the work to be done it can explode

Use only non-polarized capacitors with a maximum working voltage of 15-20% higher than that of the motor power supply and made for alternating current