Energy Metering

Presentation

The control unit calculates the different types of energy using energy meters and provides the values of:

oThe total active energy Ep, the active energy delivered (into the load) Epdelivered, and the active energy received (out of the load) Epreceived

oThe total reactive energy Eq, the reactive energy delivered (into the load) Eqdelivered, and the reactive energy received (out of the load) Eqreceived

oThe total apparent energy Es

The energy values are calculated every second, and shown as an hourly consumption. Values are stored in non-volatile memory every second.

For each energy meter two types of counter are available: one which can be reset and one which cannot be reset.

NOTE: To perform reliable energy measurement across the current range the control unit must be powered with an external 24 Vdc power supply or VPS module.

NOTE: The energies per phase are available as an option. They are calculated using the same principles as total energies.

Principle of Energy Calculation

By definition energy is the integration of the real-time power over a period T. The integration period T lasts for a number of cycles equal to the rated frequency.

 

Partial Energy Meters

For each type of energy, active or reactive, a partial received energy meter and a partial delivered energy meter calculate the accumulated energy by incrementing once a second:

oEdelivered(t) = Edelivered(t - 1) + (Gdelivered(t))/3600 where Gdelivered = Ptot or Qtot > 0

 

oReceived power is always counted negatively.

 

Ereceived(t) = Ereceived(t - 1) + (|Greceived(t)|)/3600 where Greceived = Ptot or Qtot < 0

 

For each total and partial energy meter two types of counter are available: one which can be reset and one which cannot be reset.

Energy Meters

From the partial energy meters and for each type of energy, active or reactive, an energy meter provides either of the following measurements once a second:

oThe absolute energy, by adding the received and delivered energies together. The energy accumulation mode is absolute.

 

oThe signed energy, by differentiating between received and delivered energies. The energy accumulation mode is signed.

 

The apparent energy Es is always counted positively.

Selecting Energy Calculation

The information sought determines calculation selection:

oThe absolute value of the energy that has crossed the poles of a circuit breaker or the cables of an item of electrical equipment is relevant for maintenance of an installation.

oThe signed values of the energy delivered and the energy received are required to calculate the economic cost of an item of equipment.

By default, absolute energy accumulation mode is configured.

Select the energy calculation mode using any of the following methods:

oOn the MicroLogic X display screen, on the screens Home > Configuration > Measures > E calcul

oWith EcoStruxure Power Commission software

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

Resetting Energy Meters

The energy meters can be reset as follows:

oOn the MicroLogic X display screen, on the screens Home > Measures > Energy > Reset Counter

oWith EcoStruxure Power Commission software

oWith the EcoStruxure Power Device app

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

oOn the IFE/EIFE webpages

All resettable energy meters are reset.

Resetting the energy meters generates the following event:

Presetting Energy Meters

All resettable energy meters can be preset separately, using EcoStruxure Power Commission software (password-protected).