power triangel and power factor

 power triangle and power factor

This article will shed some light on how adding capacitors gives the distribution system the necessary reactive power to return the power factor to the required level. Capacitors act as a source of reactive energy, which accordingly reduces the reactive power that the energy source must supply. The power factor of the system is therefore improved.

In an installation consuming reactive power (Diagram 1), adding a capacitor bank generating a (Diagram 2) improves the overall efficiency of the installation. The reactive power Q1 initially supplied by the source is reduced to a new value (Diagram 3), the is smaller and the cosine of this angle is improved (moves towards 1).

The current consumption is also reduced.

Power compensation enables the interests of the user and those of the energy distribution company to be combined, by improving the efficiency of installations through better use of the available power by limiting the consumption of reactive energy that is not only unnecessary and expensive but also a resource of overcurrents in conductors.

Improving the cos φ from an initial value cos φ1 to a final value cos φ2, for X (W) power used, releases an additional usable apparent power of . Therefore a 1000 kVa transformer delivering a load of 700 kW with a cosφ of 0.7 is at its maximum load.

As pricing and metering methods can vary from country to country, only a general process for assessing the need for reactive compensation, using the , will be described here. Depending on the pricing method, access to the reactive energy consumption (kvarh) may be direct, together with the number of hours to which this value refers. it is then billed proportionately.

This is generally the case for high power connections with one or more MV/LV transformers dedicated to the installation.

For lower power connections, the reactive power consumption may be indirectly billed by the overconsumption of the apparent power (in VA) that is causes. For a, it is then billed according to the amounts by which the subscribed nominal apparent power is exceeded.

In general, billing is applied when the tanφ exceeds a certain value (0.4 for example) and also according to time periods (peak times) or seasons (winter). The following calculation method, given for information purposes only, can be used to calculate the capacitor banks to be installed at the supply end of an installation with the regular, repetitive operation.

For random or sequenced operation, automatic banks, which switch on according to the load, are recommended so as not to “overcompensate” the installation.

In this type of supply contract (for example, “yellow tariff” - low power supply - in France), the reactive energy consumption is not shown on the electricity bill. It is charged indirectly. The distribution company charges a "fixed charge" that depends on the subscribed apparent power. Above this power, the consumer pays penalties. This is the principle of "monitored power".

Reactive energy compensation reduces the fixed charge by reducing the apparent subscribed power. It also enables amounts over and above this subscribed demand to be limited (billing of the additional kVA over the limit).

To determine the reactive power value to be installed, it must be compared with the savings on the fixed charge paid to the distribution company.

Nowadays reactive power is only billed for high-power installations, using direct metering (of the reactive power in kvar) or indirect metering (of the apparent power in kVA). Low power installations are billed in kW and therefore their only disadvantage is the limitation of the available current.

For responsible energy management with the aim of making better use of resources, and in view of the increasing numbers of receivers with a poor power factor (electronic power supplies, low consumption light bulbs), billing should logically move towards taking reactive power into account, will be capable of doing. Compensation of small installations will then come into its own.

 power triangle and power factor

This article will shed some light on how adding capacitors gives the distribution system the necessary reactive power to return the power factor to the required level. Capacitors act as a source of reactive energy, which accordingly reduces the reactive power that the energy source must supply. The power factor of the system is therefore improved.

In an installation consuming reactive power (Diagram 1), adding a capacitor bank generating a (Diagram 2) improves the overall efficiency of the installation. The reactive power Q1 initially supplied by the source is reduced to a new value (Diagram 3), the is smaller and the cosine of this angle is improved (moves towards 1).

The current consumption is also reduced.

Power compensation enables the interests of the user and those of the energy distribution company to be combined, by improving the efficiency of installations through better use of the available power by limiting the consumption of reactive energy that is not only unnecessary and expensive but also a resource of overcurrents in conductors.

Improving the cos φ from an initial value cos φ1 to a final value cos φ2, for X (W) power used, releases an additional usable apparent power of . Therefore a 1000 kVa transformer delivering a load of 700 kW with a cosφ of 0.7 is at its maximum load.

As pricing and metering methods can vary from country to country, only a general process for assessing the need for reactive compensation, using the , will be described here. Depending on the pricing method, access to the reactive energy consumption (kvarh) may be direct, together with the number of hours to which this value refers. it is then billed proportionately.

This is generally the case for high power connections with one or more MV/LV transformers dedicated to the installation.

For lower power connections, the reactive power consumption may be indirectly billed by the overconsumption of the apparent power (in VA) that is causes. For a, it is then billed according to the amounts by which the subscribed nominal apparent power is exceeded.

In general, billing is applied when the tanφ exceeds a certain value (0.4 for example) and also according to time periods (peak times) or seasons (winter). The following calculation method, given for information purposes only, can be used to calculate the capacitor banks to be installed at the supply end of an installation with the regular, repetitive operation.

For random or sequenced operation, automatic banks, which switch on according to the load, are recommended so as not to “overcompensate” the installation.

In this type of supply contract (for example, “yellow tariff” - low power supply - in France), the reactive energy consumption is not shown on the electricity bill. It is charged indirectly. The distribution company charges a "fixed charge" that depends on the subscribed apparent power. Above this power, the consumer pays penalties. This is the principle of "monitored power".

Reactive energy compensation reduces the fixed charge by reducing the apparent subscribed power. It also enables amounts over and above this subscribed demand to be limited (billing of the additional kVA over the limit).

To determine the reactive power value to be installed, it must be compared with the savings on the fixed charge paid to the distribution company.

Nowadays reactive power is only billed for high-power installations, using direct metering (of the reactive power in kvar) or indirect metering (of the apparent power in kVA). Low power installations are billed in kW and therefore their only disadvantage is the limitation of the available current.

For responsible energy management with the aim of making better use of resources, and in view of the increasing numbers of receivers with a poor power factor (electronic power supplies, low consumption light bulbs), billing should logically move towards taking reactive power into account, will be capable of doing. Compensation of small installations will then come into its own.