Reactive Surplus: find out what it is

Excess reactive energy is a term associated with reactive energy billing, when we consume energy, and the power factor is outside the limit of 0.92. The power factor is the quantity that defines the proportion of reactive energy consumed, compared to active energy, which is actually measured and used.

Before we understand what a fine is, let's understand the logic behind this charge.

Reactive energy is necessary, but it must be controlled so that the total amount of energy transported in the cables and conductors in the distribution system is optimized, thus avoiding large structures for poorly dimensioned consumption. (And understand that this applies to the distribution system, but the logic is equally applied to structures internal to the connection point of the concessionaire, that is, within the plant).

It is known that active energy is the “useful” energy at the end of the electromechanical energy conversion process, therefore, the idea is to use only the reactive energy necessary to guarantee the operation of the devices that perform the conversion. Thus, we have a greater proportion of active energy in the distribution system, and therefore, greater conversion efficiency, in the same structure.

When there is no control over the power factor, and therefore over the consumption of reactive energy, it is common to be charged for excess reactive energy, which is a type of fine or fee, indicating that the user is using the distribution system inappropriately, or rather, transporting more energy than necessary, and overloading the network. 

It needs active energy, but since it does not control reactive energy, in total, it needs more. In an analogous way, it is as if we were passing two fluids through the same pipe (fluid A and fluid B). Fluid A is converted into mechanical energy, fluid B is partially used, therefore, if we optimize the use of B (use only what is necessary), we can conduct a greater quantity of A.

Well, now that we understand the logic of the fine, which is nothing more than a way of pressuring consumers to optimize their energy use, how do we eliminate the reactive surplus? Or rather, how do we consume energy in an optimized way?

Let's start at the beginning: Legislation!

To talk about a reactive surplus, or rather, a surplus of reactive energy , it is important to conceptualize what this energy is (now normatively speaking), and what consumption is, so that we can understand the billing of its surplus.

According to current legislation in Brazil, via ANEEL normative resolution No. 1,000 , of December 7, 2021, which establishes the Rules for the Provision of the Public Service of Distribution of Electric Energy, and repeals the previously well-known Resolutions No. 414, No. 470, and No. 901, electric energy is defined as:

“XVI – active electrical energy: that which can be converted into another form of energy, in kWh (kilowatt-hours);”

In more popular terms, it is the energy that we actually convert into work.

“XVII – reactive electrical energy: that which circulates between the different electrical and magnetic fields of an alternating current system without producing work, in kvarh (kilovolt-reactive ampere-hour);”

Equally important in the energy conversion process, but which can become, broadly speaking, “wasted energy” if we have a large proportion of it.

We are talking about consumption over time, therefore: Active or reactive energy consumption is nothing more than the amount of electrical power (active or reactive) consumed in a period of time, expressed in kWh or kVArh.

The magnitude that relates the powers, and consequently, the energies, or consumption, or demands, is the power factor, which also has its threshold for billing defined in resolution no. 1,000:

“Art. 302. The reference power factor “fR”, inductive or capacitive, has as its minimum permitted limit the value of 0.92 for the consumer unit of group A.”

Click on the link for more information about Power Factor .

In short, we must keep the PF within limits, and for this, we use capacitor banks, which are coordinated, in their vast majority, by power factor controllers.

When we fall outside the power factor limits, the so-called “excess reactive billing” or excess reactive consumption, or even a power factor fine, the latter in popular language, comes into play.

How is reactive surplus billed?

Firstly, the utility meter measures the kWh consumed in each 15-minute window (In some cases, the integration occurs in 5-minute windows, and in this case, there is a sum of three).

Through the power factor, and depending on the quadrant, the meter separates what is active and reactive, whether capacitive or inductive, storing the information in a memory. This is commonly called mass memory.

The image above is an excerpt from a random day measured. This example memory is real and has 8928 lines, that is, 8928 measurement records.

By the way, you can request the mass memory from the dealership, or use systems to take a look to assess at what times the reactive consumption increases !?

From this memory, the dealership adds these values, and we have the values ​​that we see on the invoices, with various descriptions, explicit or not, see:

• ERE: Excess Reactive Energy;

• FER: Billing of excess reactive energy;

• UFER : Unit for Billing of Excess Reactive Energy;

• EXC TIP REAT ENERGY ( or F TIP) ;

• CAPACITIVE CONSUMPTION;

• EREX: Excess Reactive Energy X (which comes from the imaginary part of the impedance, the reactance);

• CRE: Excess Reactive Consumption;

• Among other possibilities that point to the same thing.

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These amounts are multiplied by the rates, taxes are added, and finally, the bill arrives in our email inbox for us to pay.

Okay. We understand how it all happens. What now? How to resolve the reactive surplus and not just keep paying?

How to Eliminate Reactive Surplus?

Using power factor control, from capacitors. 

Capacitors are devices that store reactive energy.

Due to the operating dynamics of consumer units in general, it is common to have a total power that compensates for the worst case, or rather, the situation with the greatest need for the insertion of capacitors, consisting of intermediate values, which are inserted according to demand.

The equipment that measures the power factor and inserts capacitors as needed is called a power factor controller .

Through power factor control and energy management systems , it is possible to eliminate reactive surplus from the bill, reducing costs and improving system performance and availability.

Control solutions of this type are widely used, have fast payback, and have several control strategies. If you want to know more about the subject, or have a problem of this type, contact us!