MicroLogic X control units perform the following real-time tasks:

oMeasure the following currents in real time and as an RMS value:

oCurrent for each phase and the neutral (if present)

oGround-fault current

oEarth-leakage current (MicroLogic 7.0 X)

oCalculate the average current in real time

oDetermine the maximum and minimum values for these electrical quantities

oMeasure the phase-to-phase and phase-to-neutral voltage (if present), in real time and as an RMS value

oCalculate the associated electrical quantities from the RMS values of the currents and voltages:

oAverage phase-to-phase voltage and phase-to-neutral voltage (if present)

oCurrent unbalances

oPhase-to-phase voltage unbalances and phase-to-neutral voltage unbalances (if present)

oCalculate the associated electrical quantities from the current and voltage samples:

oQuality indicators: frequency, THD(I), THD(V), THD-R(I), and THD-R(V), and power factor PF and cos φ measurement

oDisplay operating indicators: quadrants, and type of load

oDetermine the maximum and minimum values for these electrical quantities

The sampling method uses the values of the harmonic currents and voltages up to the fifteenth order. The sampling process tracks the fundamental frequency and provides 40 samples per fundamental cycle.

The values of the electrical quantities, whether measured or calculated in real time, update once a second at rated frequency.

On 3-pole circuit breakers, the system type setting allows the activation of:

oThe ENCT (external neutral current transformer)

oThe ENVT (external neutral voltage tap)

The system type can be set as follows:

oOn the MicroLogic X display screen, at Home > Configuration > Measures > System Type.

oWith EcoStruxure Power Commission software (password-protected)

oBy sending a setting command using the communication network (password-protected)

4-pole circuit breakers or 3-pole circuit breakers with the ENCT wired and configured measure the neutral current:

oFor a 3-pole circuit breaker, the neutral current is measured by adding a current transformer on the neutral conductor for the transformer information. For more information, refer to MasterPact MTZ Catalogue.

oFor a 4-pole circuit breaker, the neutral current is measured systematically.

The neutral current is measured in the same way as the phase currents.

Measuring the Ground-Fault Current

The ground-fault current is calculated or measured in the same way as the phase currents, according to the circuit breaker configuration, as shown in the following table.

Circuit breaker configuration |
Ig ground-fault current |
---|---|

3P |
Ig = I1 + I2 + I3 |

4P |
Ig = I1 + I2 + I3 + IN |

3P + ENCT |
Ig = I1 + I2 + I3 + IN (ENCT) |

3P or 4P + SGR |
Ig = ISGR |

Measuring the Earth-Leakage Current (MicroLogic 7.0 X)

The earth-leakage current is measured by a rectangular sensor encompassing the three phases or the three phases and neutral.

Measuring the Phase-to-Neutral Voltages

4-pole circuit breakers, or 3-pole circuit breakers with the ENVT wired and configured, measure the phase-to-neutral (or line-to-neutral) voltages V1N, V2N, and V3N:

oFor a 3-pole circuit breaker, it is necessary to:

oConnect the wire from the ENVT to the neutral conductor

oDeclare the ENVT in the system type setting

oFor 4-pole circuit breakers, the phase-to-neutral voltages are measured systematically.

The phase-to-neutral voltages are measured in the same way as the phase-to-phase voltages.

Calculating the Average Current and Average Voltage

MicroLogic X control units calculate the:

oAverage current Iavg, the arithmetic mean of the 3 phase currents:

oAverage voltages:

oPhase-to-phase Vavg, the arithmetic mean of the 3 phase-to-phase voltages:

oPhase-to-neutral Vavg, the arithmetic mean of the 3 phase-to-neutral voltages (4-pole circuit breakers or 3-pole circuit breakers wired and configured with the ENVT):

Measuring the Current and Voltage Phase Unbalances

MicroLogic X control units calculate the current unbalance for each phase (3 values) and the maximum current unbalance.

The current unbalance is a percentage of the average current:

MicroLogic X control units calculate:

oThe phase-to-phase voltage unbalance for each phase (3 values) and the maximum of 3 phase-to-phase voltage unbalances.

oThe phase-to-neutral (if present) voltage unbalance for each phase (3 values) and the maximum of 3 phase-to-neutral voltage unbalances.

The voltage unbalance is expressed as a percentage compared to the average value of the electrical quantity (Vavg):

The MicroLogic X control unit determines the maximum (MAX) and minimum (MIN) value reached by the following electrical quantities for the period from the last reset to the present time:

oCurrent: phase and neutral currents, average currents, and current unbalances

oVoltage: phase-to-phase and phase-to-neutral voltages, average voltages, and voltage unbalances

oPower: total power and phase power (active, reactive, and apparent)

oTotal harmonic distortion: the total harmonic distortion THD and THD-R for both current and voltage

oFrequency

oThe maximum of the maximum value of all phase currents

oThe minimum of the minimum value of all phase currents

oThe maximum of the maximum value of 3 phase current unbalances

oMaximum of maximum of 3 phase-to-phase voltage unbalances

oMaximum of maximum of 3 phase-to-neutral voltage unbalances

Resetting Maximum/Minimum Values

The maximum and minimum values can be reset as follows:

oOn the MicroLogic X display screen, at:

oHome > Measures > Current

oHome > Measures > Voltage

oHome > Measures > Power

oHome > Measures > Frequency

oHome > Measures > I Harmonics

oHome > Measures > V Harmonics

oWith EcoStruxure Power Commission software

oWith the EcoStruxure Power Device app

oBy sending a command using the communication network (password-protected).

oOn the IFE/EIFE webpages

NOTE: The maximum and minimum power factors and cos φ can be reset only:

oWith EcoStruxure Power Commission software

oBy sending a command using the communication network (password-protected).

oOn the IFE/EIFE webpages

All maximum and minimum values for the group of electrical quantity selected are reset.

Resetting maximum and minimum values generates the following events:

Code |
User message |
History |
Severity |
---|---|---|---|

0x0F12 (3858) |
Reset Min/Max currents |
Metering |
Low |

0x0F13 (3859) |
Reset Min/Max voltages |
Metering |
Low |

0x0F14 (3860) |
Reset Min/Max power |
Metering |
Low |

0x0F15 (3861) |
Reset Min/Max frequency |
Metering |
Low |

0x0F16 (3862) |
Reset Min/Max harmonics |
Metering |
Low |

0x0F17 (3863) |
Reset Min/Max power factor |
Metering |
Low |