Energy Metering (MicroLogic E)

Presentation

The MicroLogic E trip unit calculates the different types of energy using energy meters and provides the values of:

• The active energy Ep, the active energy supplied EpOut, and the active energy consumed EpIn

• The reactive energy Eq, the reactive energy supplied EqOut, and the reactive energy consumed EqIn

• The apparent energy Es

The energy values are shown as an hourly consumption. Values update once a second. Values are stored in non-volatile memory once an hour.

Principle of Energy Calculation

By definition

• Energy is the integration of the instantaneous power over a period T:

  

• The value of the instantaneous active power P and the reactive power Q can be positive (power consumed) or negative (power supplied) according to the operating quadrant.

• The value of the apparent power S is always counted positively.

Partial Energy Meters

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

• The contribution of the instantaneous power consumed for the energy consumed meter

  

• The contribution as an absolute value of the power supplied for the energy supplied meter (power supplied is always counted negatively)

  

The calculation is initialized by the last reset action.

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:

• The absolute energy, by adding the consumed and supplied energies together. The energy accumulation mode is absolute.

  

• The signed energy, by differentiating between consumed and supplied energies. The energy accumulation mode is signed.

  

The apparent energy Es is always counted positively.

Selecting Energy Calculation

The information sought determines calculation selection:

• The 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.

• The signed values of the energy supplied and the energy consumed are required to calculate the economic cost of an item of equipment.

By default, absolute energy accumulation mode is configured.

The setting can be modified:

• With EcoStruxure Power Commission software (password-protected)

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

Resetting Energy Meters

Reset the energy meters using:

• The communication network (password-protected)

• The FDM121 display

• An input of the IO module

There are two additional active energy accumulation meters (EpIn and EpOut) that cannot be reset.