MicroLogic Active E Power Factor PF and cos φ Measurement

Power Factor PF

The MicroLogic Active E control unit calculates the total power factor PF from the total active power Ptot and the total apparent power Stot:

This indicator qualifies:

• The oversizing necessary for the installation power supply when harmonic currents are present.

• The presence of harmonic currents by comparison with the value of the cos φ (see below).

cos φ

The MicroLogic Active E control unit calculates the cos φ from the total fundamental active power Pfundtot and the total fundamental apparent power Sfundtot:

This indicator qualifies the usage of the fundamental energy and defines the quadrant of operation. The cos φ is also called the Displacement Power Factor (DPF).

Sign for the Power Factor PF and cos φ

Two sign conventions can be applied for these indicators:

• IEC convention: The sign for these indicators complies strictly with the signed calculations of the powers (that is, Ptot, Stot, Pfundtot, and Sfundtot).

• IEEE convention: The indicators are calculated in accordance with the following formula:

The following figures define the sign for the power factor PF and cos φ by quadrant (Q1, Q2, Q3 and Q4) for both conventions:

IEC Convention
Operation in all quadrants (Q1, Q2, Q3, Q4)	Values of cos φ in receiver operation (Q1, Q4)

IEEE Convention
Operation in all quadrants (Q1, Q2, Q3, Q4)	Values of cos φ in receiver operation (Q1, Q4)

NOTE: For a device, a part of an installation which is only a receiver (or generator), the advantage of the IEEE convention is that it adds the type of reactive component to the PF and cos φ indicators:

• Lead: positive sign for the PF and cos φ indicators.

• Lag: negative sign for the PF and cos φ indicators.

Monitoring the cos φ and Power Factor PF Indicators

According to the IEEE convention, critical situations in receiver mode on a capacitive or inductive load are detected and differentiated (two values).

The following table indicates the direction in which the indicators vary and their value in receiver mode:

According to the IEC convention, critical situations in receiver mode on a capacitive or inductive load are detected but not differentiated (one value).

Selecting the Sign Convention for the cos φ and Power Factor PF

Set the sign convention for the cos φ and PF indicators on the MicroLogic Active E display screen, from the tree navigation menu, at Configuration > Measures > PF / Var

The factory setting of the sign convention is IEC.