User manual 09/2009 - Schneider Electric

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User manual 09/2009 - Schneider Electric

The Metering FunctionEnergy Metering (Micrologic E)PresentationThe Micrologic E trip unit calculates the different types of energy by means of energy meters and providesthe 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 EsThe energy values are indicated as an hourly consumption. These values are updated once a second.The energy values are stored in non-volatile memory once an hour.NOTE: When there is a weak current through the circuit-breaker (15 to 50 A depending on the rating), itis necessary to power the Micrologic E with an external 24 VDC power supply to calculate the energies.See Micrologic Trip Unit Power Supply, page 17.Principle of Energy CalculationBy 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 (powerconsumed) or negative (power supplied) according to the operating quadrant (see Power Sign andOperating Quadrant, page 82).• The value of the apparent power S is always counted positively.Partial Energy MetersFor each type of energy, active or reactive, a partial energy consumed meter and a partial energysupplied 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 (powersupplied is always counted negatively)The calculation is initialized by the last Reset action (see Resetting Energy Meters, page 86).Energy MetersFrom the partial energy meters and for each type of energy, active or reactive, an energy meter provideseither of the following measurements once a second:• The absolute energy, by adding the consumed and supplied energies together: the energyaccumulation mode is absolute• The signed energy, by differentiating between consumed and supplied energies: the energyaccumulation mode is signedThe apparent energy Es is always counted positively.Selecting Energy CalculationThe calculation selection is determined by the information sought:• The absolute value of the energy that has crossed the poles of a circuit breaker or the cables of anitem of electrical equipment is a relevant parameter for maintenance of an installation.• The signed values of the energy supplied and the energy consumed are needed to calculate theeconomic cost of an item of equipment.By default, absolute energy accumulation mode is configured.The parameter setting can be modified using the RSU software (see Metering Setup, page 123).LV434104 09/2009 85

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