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We have put together some explanations of technical terms and phrases specific to the energy industry.



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Active power
Active power (W) is the electrical energy available for transformation into other types of energy. Active power is restricted by reactive power (Var) which cannot be used for this transformation. Together, active power and reactive power give the apparent power (VA) for an electricity plant.

Apparent power (VA, kVA or MVA)
The apparent power is an operand that is taken into account with respect to the losses and the loads placed on the components in an energy supply system when electrical power is supplied to an electrical consumer. The apparent power does not necessarily match the power relayed by the consumer in the form of thermal or mechanical energy or energy of a different type. The apparent power S is defined by the effective value of electrical current I and electrical voltage U, and consists of the active power P that is actually transferred and additional reactive power Q.

As the reactive power diminishes, e.g. with DC voltage, the apparent power is either the same as, or more than, the active power. Electrical equipment designed to transfer a preset amount of active power, such as transformers or electrical cables, have to be designed to accommodate the greater apparent power. The electrical connected capacity is also often indicated as apparent power.

The unit volt-ampere (VA) is used to measure apparent power.

1,000 VA = 1 kVA
1,000 kVA = 1 MVA

See also 'Volt-ampere'.


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electrical connector between all switch fields. A triple busbar can be fed each switch field from one of three separate busbars. This means that different electrically separate switch field groups can be operated.


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Cable distribution cabinet (CDC)
The cable distribution cabinet is a node for electrical cables in the low-voltage grid (0.4 kV). The cables and the house connections linked to them are fused via the CDC. If there is a fault in the cable, the fuse for the length of cable trips in the CDC, so that only a few house connections and/or customers are affected by the outage.

Physical value of the energy turnover in a given time period, expressed in watts (W)

Capacity connection
Power which can be transmitted between the transmission grid and the distribution network.

A concession is the right to use common property, which is issued through a lease or an award by the relevant national or community authorities. Stromnetz Berlin GmbH has received a concession from the Berlin region to use public thoroughfares in Berlin to lay cables and install operating equipment.

Connected capacity
The connected capacity – also known as the connected load – is the maximum power made available by the network operator at the respective terminal point and used in the design of the installation to supply electrical energy.

Generally speaking, the connected capacity is defined as apparent power in the case of electrical energy.

Connection usage
Connection usage is the use of an available connection to receive electrical energy.

Connection use agreement
The connection user and the grid operator conclude a connection use agreement for the use of electricity through the distribution grid connection. The connection user shall conclude an agreement for the use of electricity prior to first use, or the requirements for an emergency supply must be met pursuant to Section 38 of the Energy Industry Act (Energiewirtschaftsgesetzt - EnWG).

Connection user
The connection user utilises the customer's system for obtaining electricity as an end user or for feeding electricity from a private system into the distribution network. The contractual relationships between the distribution system operator and connection user are stipulated in the connection use agreement.

The customer and connection user may be the same person. A house and property owner is usually both customer and connection user, but a tenant is only the connection user.

Consumers (as per Section 13 BGB)
A consumer is any natural person who concludes a legal transaction for purposes which are primarily attributable to neither
their commercial nor their independent professional activity.

Under Section 13 BGB, the consumer is subject to an additional restriction (in comparison to household customers under EnWG), because for household customers under EnWG, own consumption of up to 10,000 kWh for professional, agricultural and commercial purposes is also taken into account.

CO2 emission
CO2 emissions are the product of the multiplication of annual electricity consumption in Berlin and the CO2 emission factor for the German electricity mix. The CO2 emission factor is determined and published annually by the Federal Environment Agency (Umweltbundesamt - UBA).

2016 = 524 g CO2/kWh
2017 = 487 g CO2/kWh
2018 = 473 g CO2/kWh
2019 = 411 g CO2/kWh
2020 = 369 g CO2/kWh
2021 = 410 g CO2/kWh (provisional)
2022 = 434 g CO2/kWh (estimated)

Calculation i. e. for 2022
Annual electricity consumption : 12.5 TWh = 12,500,000,000 kWh
CO2 emission =
12,500,000,000 kWh x 434 g CO2/kWh = 5,425,000,000,000 g CO2 = ~5.425 mio t CO2

You will find further information on the website of the UBA.

The property owner whose electrical system is directly connected to the distribution network is classed as the customer. This may refer to a connection to a private home or company premises. The contractual relationships between the distribution system operator and customer are stipulated in the grid connection agreement.


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Distribution system operator
A natural or legal person with the task of distributing electricity and who is responsible for the operation, maintenance and, as applicable, the expansion of the distribution grid in a particular area.


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Electricity supplier
Electricity suppliers purchase energy at the electricity exchange or directly from generators and sell this to their customers. An electricity supply contract is concluded with the customer. The electricity supplier generally deals with the customer's grid usage as well. To do this, the electricity supplier will have concluded a grid usage contract with the grid operator.

End user
Natural or legal persons who purchase energy for own consumption.


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A fee must be paid to the grid operator for use of the distribution grid and necessary services e.g. provision of a meter. The amount of this fee depends on energy used (kWh), the capacity provided (kW), duration of usage (p.a.) and services provided (number).


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Granting concessions
The concession holder, i.e. Stromnetz Berlin GmbH, must pay a release fee to the concession issuer for the concession. The amount of the concession is stipulated in the Concession Release Ordinance [Konzessionsabgabenverordnung (KAV)] and is calculated using energy consumed.

Grid connection and connection usage contract
The contract combines the grid use contract with connection usage.

Grid connection contract
The contract regulates all connection details. For a low voltage connection (0.4 kV), this includes all information under Section 4 of the low voltage connection ordinance [Niederspannungsanschlussverordnung (NAV)]. For higher voltage levels, the contractual conditions should be similar.

Grid losses
Physically-caused losses occur when electrical energy is transported through cables and wiring and during transformation. The total of the losses at all voltage levels gives a grid operator's grid losses. Grid losses must be equalised by the grid operator so that customers receive the actual desired amount of energy.

Grid station
Small transformer station in which the voltage is switched from 10 kV to 0.4 kV using a transformer.


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Household customer
A household customer is an end user who is primarily purchasing electricity for own use in their household. Household customers also include those customers with an annual consumption of 10,000 kWh or less for professional, agricultural or commercial purposes.


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Kilovolt (kV)
Electrical voltage is a physical value that shows how much energy is required to move an electrical charge within an electrical field. Voltage is expressed in volts (V).
1 kV (Kilovolt) = 1000 V (Volt)

Kilowatt hour (kWh)
The kilowatt hour is the physical unit of measurement for electrical work.

1000 kWh = 1 MWh (megawatt hour)
1000 MWh = 1 GWh (gigawatt hour)
1000 GWh = 1 TWh (terrawatt hour)


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The load is the capacity and/or amount of electricity currently being used by all consumers using the energy grid. The load is measured in watts.

Load curve
A load curve is the total of all average power values which are measured in a discrete number of measurement periods. A measurement period lasts 15 minutes. The total of four 15-minute values corresponds to the energy consumption in one hour.

Load curve customer
A load curve customer's electricity consumption is measured and charged using a load curve.

Load profile
A load profile is a time sequence which sets an average power value for each calculation period. In this process, the time sequence and the average performance values represent the typical consumption behaviour of a particular customer group.

There are load profiles for households, business, agriculture and base load.

Load profile customer
Customers with an annual energy consumption of under 100,000 kWh are generally charged using a load profile and the energy measured by the meter.


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Measurement service providers
The measurement service provider is the grid operator or a third party which offers measurement services (reading measurement values) for measuring equipment which cannot be read electronically.

Meter operators
The meter operator is the grid operator or a third party which is responsible for the installation, operation and maintenance of meters.

Megavolt-ampere - see volt-ampere


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OBIS number
OBIS is an abbreviation of Object Identification System. The OBIS number is used as a unique identifier for measurement values (e.g. amount of energy, meter status) and also for other details for electronic data exchange between the grid operator and the energy supplier.


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Reactive power
Reactive power is a term used in electrical engineering.

In an electrical energy supply network, energy is supposed to be transferred from the generator to the consumer. In electricity networks with one-phase or three-phase alternating current, more energy often flows from the generator (power station) to the electrical consumer (e.g. an electric machine) than is used by the consumer. This additional energy per time that does not contribute to the active power ("actual power") is generally undesirable and is referred to as reactive power.

Reactive power is indicated using the unit 'var'.


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Smart grid
The term Smart Grid is used to describe intelligent energy grids. A Smart Grid meets all the demands of modern energy distribution and enables customer and generation plant connections.

Natural or legal person whose business activities wholly or partly involve selling energy for delivery to end users.


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Transformer station
In a transformer station, a transformer is used to switch the voltage from 110 kV (high voltage) to 10 kV (medium voltage).

Transmission station
The transmission station is used to connect a high or medium voltage customer plant to the distribution grid.

Transmission system operator
The transmission system operator is responsible for transporting energy in their grid area over longer stretches. They are also responsible for maintaining frequency stability, i.e. balancing the energy fed into the grid and the energy withdrawn from the grid. There are four transmission system operators in Germany (50 Hertz Transmission GmbH, Tennet TSO GmbH, Amprion GmbH and TransnetBW GmbH).


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Electrical voltage is a physical value that shows how much energy is required to move an electrical charge within an electrical field. Voltage is expressed in volts (V).

The connection capacity of an electrical machine or a transformer is represented using the physical value of volt-amperes (VA). This shows the apparent power, a combination of active power (W) and reactive power (Var).

Electrical voltage is a physical value which shows how much energy is required to move an electrical charge within an electrical field. Voltage is expressed in volts (V).

Voltage levels
The three voltage levels in Berlin's distribution grid are 110,000 V (110 kV), 10,000 V (10 kV) and 400 V (0.4 kV). Connected customers can be provided with different capacities depending on the voltage level. Customers with very large capacity requirements are connected to the high voltage grid (110 kV), customers with large capacity requirements to the medium voltage grid (10 kV) and private and business customers to the low voltage grid (0.4 kV).


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Watt (W)
The watt is the general unit of measurement for the physical value "capacity".