Power harmonics detection devices

Measurements are the first step in gaining control over harmonic pollution. Depending on the conditions in each installation, different types of equipment provide the necessary solution.

PowerLogic System with Power Meter and Circuit Monitor, Micrologic offer a complete range of devices for the detection of harmonic distortion

Power-monitoring units

Power Meter and Circuit Monitor in the PowerLogic System
These products offer high-performance measurement capabilities for low and medium-voltage distribution networks. They are digital units that include power-quality monitoring functions.
PowerLogic System is a complete offer comprising Power Meter (PM) and Circuit Monitor (CM). This highly modular offer covers needs ranging from the most simple (Power Meter) up to highly complex requirements (Circuit Monitor). These products can be used in new or existing installations where the level of power quality must be excellent. The operating mode can be local and/or remote.
Depending on its position in the distribution network, a Power Meter provides an initial indication on power quality. The main measurements carried out by a Power Meter are:

• Current and voltage THD
• Power factor

Depending on the version, these measurements can be combined with time-stamping and alarm functions.
A Circuit Monitor (see Fig. M14) carries out a detailed analysis of power quality and also analyses disturbances on the distribution network. The main functions of a Circuit Monitor are:

• Measurement of over 100 electrical parameters
• Storage in memory and time-stamping of minimum and maximum values for each electrical parameter
• Alarm functions tripped by electrical parameter values
• Recording of event data
• Recording of current and voltage disturbances
• Harmonic analysis
• Waveform capture (disturbance monitoring)

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Fig. M14: Circuit monitor

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Micrologic - a power-monitoring unit built into the circuit-breaker
For new installations, the Micrologic H control unit (see Fig. M15), an integral part of Masterpact power circuit-breakers, is particularly useful for measurements at the head of an installation or on large outgoing circuits.
The Micrologic H control unit offers precise analysis of power quality and detailed diagnostics on events. It is designed for operation in conjunction with a switchboard display unit or a supervisor. It can:

• Measure current, voltage, active and reactive power
• Measure current and voltage THD
• Display the amplitude and phase of current and voltage harmonics up to the 51st order
• Carry out waveform capture (disturbance monitoring)

The functions offered by the Micrologic H control unit are equivalent to those of a Circuit Monitor.

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Fig. M15: Micrologic H control unit with harmonic metering for Masterpact NT and NW circuit-breakers

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Operation of power-monitoring units

Software for remote operation and analysis
In the more general framework of a distribution network requiring monitoring,
the possibility of interconnecting these various devices can be offered in a communication network, thus making it possible to centralise information and obtain an overall view of disturbances throughout the distribution network.
Depending on the application, the operator can then carry out measurements in real time, calculate demand values, run waveform captures, anticipate on alarms, etc.
The power-monitoring units transmit all the available data over either a Modbus, Digipact or Ethernet network.
The essential goal of this system is to assist in identifying and planning maintenance work. It is an effective means to reduce servicing time and the cost of temporarily installing devices for on-site measurements or the sizing of equipment (filters).

Supervision software SMS
SMS is a very complete software used to analyse distribution networks, in conjunction with the products in the PowerLogic System. Installed on a standard PC, it can:

• Display measurements in real time
• Display historical logs over a given period
• Select the manner in which data is presented (tables, various curves)
• Carry out statistical processing of data (display bar charts)