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The problem: reactive power, cos φ, harmonics, load variations

Loaded electrical network

Loaded electrical network

Green – active load, red – reactive power

Reactive power

Apparent power, reactive power

Although the mechanical effect of the motor requires only 500 kW, the electrical network is loaded with an apparent load (S) of 714 kVA, i.e. with 143% of the active load (P).

Negative effects of harmonics

Harmonic currents represent an additional load on all electrical equipments. The consequences may be:

  • Increased energy costs resulting from power/heat losses
  • Faults in communication and control systems
  • Shaking moments and irregular operation of electric equipment
  • Reduced lifetime
  • Overloading of electric equipment
  • Deficient product and process quality
  • Higher CO2 emissions

Symbolic representation of a electrical network loaded with reactive current and harmonics

Symbolic representation of a system loaded with reactive current and harmonics

Negative consequences of fast load changes

  • Excessive impulsive over-currents
  • Unstable voltage conditions
  • Unbalanced phases
  • Increased losses
  • Increased equipment costs
  • Flicker voltage fluctuations
  • Deficient product and performance quality,
  • Higher CO2 emissions

Negative effects of the capacitive load

The effects are similar as with an inductive load. In addition, there is a risk of voltage increases or drops leading to the known negative consequences.

The solution: Power factor correction

Power factor correction

Power factor correction

In the given example, the motor consumes an active power (P) of 500 kW; the reactive power (Q1) of the motor is fully compensated by Qcorr and the electrical network is loaded now with an apparent power (S2) of 500 kVA, 100% with active power. The power factor correction leads to an unloading of 43% (from 143% to 100%, related to the active power rating).

The economic advantages of power factor correction

Additional savings from active power costs by reducing the losses

The previously shown company has, like every other power consumer, power losses in its own distribution network and pays for active power. The use of a power factor correction system reduces the apparent power in the electrical network of the companyand hence also the power losses. In addition to saving reactive power costs, the power factor correction system also reduces the costs for the active power, i.e. all the more as the cos φ is increased.


Lowering of investment costs

The previously shown company is planning to increase its consumption by 200 kW from 500 kW. The existing transformer with a rating of 800 kVA has been adequate to date, but it would be overloaded after the plant expansion. An extension of the power infrastructure with a transformer, switchgear, cabling, distribution board, etc. would be necessary.

In this case the apparent power can be reduced by using power factor correction system beyond the required cos φ of 0.9 so that the existing infrastructure is still sufficient. Such a power factor correction system is significantly less expensive than a electrical network expansion and would likewise save energy costs.

An innovative, network-optimizing power factor correction can do more

Schematic of a electrical network relieved from reactive power
and harmonics

Electrical network relieved from reactive power and harmonics


Although power factor correction is basically not able to replace electrical network expansions durably, but bottlenecks would be alleviated and precious time would be gained for the expansion due to the free line capacity accomplished through an optimized use of power factor correction or an increase of the target cos φ close to 1. In addition, the CO2 emissions would be reduced considerably. A target cos φ close to 1 would also contribute to environmental protection

The advantages of an innovative, network-optimizing power factor correction
at national level

Power load and losses depending on the power factor

Power load and network losses depending on the power factor

Power Factor correction in Germany

Power Factor correction in Germany

The innovative, network-optimizing power factor correction of SYSTEM ELECTRIC is energy-efficient, relieves electrical networks from the inductive as well as the capacitive reactive power, reduces current/heat losses, and decreases current peaks and harmonics – in real time, if required.