Audio Frequency Feed In Transformers

Audio Frequency Feed In Transformers for medium voltage applications are since decades a main part of EPRO is production program. 

Due to the extreme high reliability of these devices with lifetimes of 30 years and more these devices still face worldwide demand. 

Our customers in this area are the electric utility companies, mainly in Europe and plant manufacturers.



What are feed-in transformers / converter couplings and what are they used for?
Feed-in transformers are the link between the ripple control transmitter and the power grid.
They are used to overlay the audio frequency, which is generated by the transmitter and at the same time to protect the network from interference frequencies.
Feed in transformers for example are used to switch between day and night power-tariffs.


How does the switching between day and night power tariffs work?
To operate power plants economically and cost-efficient, the capacity should be as constant as possible. In order to lower the peaks, energy is offered to a lower price during periods of lower load. This is done due to tariff switchovers with ripple control systems.
Audio Frequency Feed in Transformers are overlaying the network with a certain voltage, frequency and signal pattern, a receiver at the end consumer converts the signals and switches between the tariffs due to relais.


What problems can arise when switching tariffs?
Frequency control transmissions, such as those used for tariff switching in ripple control systems, can be disturbed by various sources of interference such as compensation systems at the consumer, electronic frequency converters (e.g. at alternative power plants) or even with cable networks with high capacities.
Interference frequencies attenuate the transmission level in the smart grid and cause failures and incorrect switching in the ripple control.


What prevents interference frequencies in the medium-voltage grid?
EPRO´s Audio Frequency suppressors are used to block unwanted audio frequency voltages in the medium-voltage grid (e.g. in wind power plants). Another application is the remote control of the audio frequency signal from sensitive customer networks. (see audio frequency suppressors)


In which execution are feed-in transformers available?
The devices are offered in serial or parallel versions for indoor and outdoor use.
Series couplings: Feed in Transformer/ converter coupling (Type FET + ET) and transformer coupling (type FGS)
Parallel coupling (type KT + FKT)