Electrical Power Factor in Schematic Diagram

Power Factor Formula in Diagram and BERC Code

Every day we use electrical energy for industrial, commercial or residential purposes and pay bills to the utility department end of the month. Maximum of us do not think, we are paying extra money bill of our users just because of power factor. Simply look at the following diagram, our using amount is kW, the unusable amount is kVAR, but we are paying for some of both is kVA, just cause of a mug of drinks.

Electrical Power Factor in Schematic Diagram

Of course, there is a solution. If you are intelligent, you will pour your drinks soft and gently which makes less loss. Similarly taking necessary action to correct the power factor, we can reduce electrical power waste or loss.

Generally, we use 3 types of load. Resistive, Inductive and Capacitive. The resistive load has no effect on the power factor, mainly resultant inductive load causes of waste of power. The capacitive load character is just opposite the inductive load. So, using capacitive load as a counter of inductive load power factor improvement is possible.

Hope you gather some basic knowledge about today's topic  Electrical Power Factor in Schematic Diagram. We will try to more topics next time.

How do I use inductors for power factor correction?

Most of the electrical equipment draws inductive reactive power (Var) from the supply system for its operation. The current lags the voltage in the inductive loads/ combination of resistance and inductive loads.

The induction motor and the transformer draws reactive power for setting up a magnetic flux in the magnetic core.

The reactive power drawn by the electrical equipment increases the line current. The line power loss (I^2R loss) increase with an increase in the line current.

For nullifying the increased current caused by inductive loads, the capacitor is added to the circuit. The current always leads the voltage in the capacitor. Thus the current drawn by the capacitor is just in phase opposition to the inductive reactive current drawn by the electrical equipment, and thus the power factor of the system improves if a capacitor is used for pf compensation.



This way the line current gets reduced and the system power factor improves, and the line power loss gets decreased accordingly.

What Is The Reason for Low Power Factor?

There are basically two reasons for the low power factor.

One reason is that the load has an inductive component, as discussed in the previous answers. Capacitors are effective to correct low power factors because of an inductive load.

The second reason for the low power factor is a non-linear load caused by a rectifier bank or other switching device, such as an SCR used for phase control. The switching of current causes harmonics on the powerline. These harmonics in the current waveform, which are not in phase with the voltage waveform, cause a low power factor. An inductor placed in series with the switching device puts a high impedance in series with the harmonic currents, reduces their amplitude and improves power factor. Because the harmonic currents are at least 3 times higher in frequency than the powerline, it doesn’t take a very high inductance to stop them.

The other use of an inductor for power factor correction is, together with capacitors, to make a harmonic trap. A harmonic trap is a tuned circuit, resonant at the undesired harmonic frequency. Depending on the application, either a parallel resonant trap is connected in series with the load or a series resonant trap is connected in parallel with the load.


Capacitors alone are not effective to correct the low power factors caused by a non-linear load; in many cases, they will make the power factor lower, not higher.

Bangladesh Electricity Distribution Code Published by Bangladesh Energy Regulatory Commission

The consumer of applicable category declared by the Commission shall so 73 arrange his installation that the average power factor of his load during any billing period is maintained not less than 0.95 lagging or any other limit set by the Commission. 

Power factor penalty with or without capping limit as set by the Commission shall be levied if there is a breach of the aforesaid requirement, however, the supply of power shall be disconnected serving 7(seven) days notice for rectification if the average power factor in 3 consecutive billing cycle falls below 0.70 : 

If, after considering the reply to the show causes notice, the Authorized Officer decides to disconnect, he shall communicate his order to the consumer and disconnect supply after 7(seven) days of such communication. 

Instantaneous Power Factor reading may be recorded for monitoring but shall not be used for billing purposes. Power Factor penalty shall not be applicable where kVAR-h meter is not available or functional.

Provided that there shall be no disconnection without giving the consumer 7(seven) clear days notice in writing to show cause to the Authorized Officer why the supply of power should not be disconnected. 

Power Factor shall be determined for the entire billing period by utilizing kWh and kVArh for the respective months. 

However, the Power Factor of the Master/Mother/Check Account shall be determined by deducting the Σ kWh and Σ kVArh of Child/Supplementary/Sub-Account(s). In absence of Σ kVArh of Child/Supplementary/Sub-Account(s), the kVArh of Master/Mother/Check meter shall be calculated in proportion of kWh.