Thyrobox VR Voltage Regulation of distribution grids

AEG Power Solutions offers the Thyrobox VR as a solution for occurring issues due to feed from renewable energies (solar and wind) into the electric grid and the therefore needed voltage stability for all consumers. Profitability, reliability and reproducibility are a must-have for the key properties of this power supply.

Voltage Regulation, renewable energies electric grid

Thyrobox VR - Key Features

  • Continuous voltage regulation
  • Extremely robust SCR thyristor technology
  • Small footprint
  • High degree of efficiency > 99%
  • 100% fail safe
  • High degree of reliability
  • High degree of availability
  • Long operating life
  • Digital technology with precise accuracy
  • Excellent technical support
  • Excellent price/performance ratio
  • Short delivery times
  • High power factor
  • Minimized system perturbation
  • Meets industry standards

Thyrobox VR - Description

Voltage Regulation

With the growing number of solar installations, requirements increase for local distribution system operators and their existing network infrastructures. In the past electrical distribution systems have been designed for a power fl ow from high voltage via medium voltage to low voltage with the consumer or end user being a sink of electrical energy. Now, the user can become a source of electrical energy. In this case the power flow is reversed and voltage drops on impedance reverse as well. This can result in exceeding the upper voltage tolerance (+10%) especially in network spur lines. Without any changes at the existing network infrastructure this would cause automatic switch-off of solar inverters with the consequences of dissatisfi ed customers and additionally failure to meet legal objectives as preferred by renewable energies.



These requirements confront local distribution grid operators, especially in the countryside, ie where farms or sports clubs are connected via spur lines. Up until now the only solution has been to install new cables in expensive and time consuming installations. This causes undesirable delay and additional cost for the operator. With Thyrobox VR, AEG Power Solutions offers a new concept.


Thyrobox VR operates as a voltage regulator within low voltage networks. Once the power fl ow reverses, the voltage of the secondary connected network segment will be adjusted downwards by up to 8%. Regulation is continuously stepless with no switching operations and a degree of effi ciency >99% according to power rating. Therefore the voltage range is signifi cantly easier to utilize and the installation of cables can be avoided in many cases.

The basic technology has been known of since the late 1920’s and has been upgraded in the 1970’s using SCR semiconductor devices with step control. AEG PS has further developed the technology for continuous regulation and brought it to a state of the art hardware platform using best in class thyristors and controllers. The Thyro-P control unit has been proven over many years in demanding applications and also provides necessary interfaces to various communication tools.

The dimensional construction of Thyrobox VR is similar to common cable distribution cabinets. The installation is similar to cable distribution cabinets i.e. on a concrete base, through which the cables will pass and therefore an installation is possible along sidewalks, cycle ways and side roads.

Product Sheets:

Operating Instructions:


Voltage Control in distribution Grids

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Thyrobox VR - Specifications


Technical data Thyrobox VR

Phase voltage

3 x 400 Vac

Transmission load

125 kVA, 250 kVA

Controlling range/voltage

0 up to -8%


continuous voltage regulation

Short circuit voltage Uk

< 0.1%

Protection code

IP 54

Overvoltage protection

for surges and switching operations

Potential equalization

grounding connection

Terminal box

connection from below

Short circuit protection

external fuses to be installed in the feeding cable

Fail safe

bypass device in case of short circuits or severe failures


air cooling

Type of cabinet

outdoor metal cabinet

Temperature range

-20°C up to 45°

Acoustic noise

< 45 dBA


125 kVA: approx. 325 kg
250 kVA: approx. 385 kg


1355 mm (H) x 1250 mm (W) x 460 mm (D)

* further data/characteristics on request


Kostengünstige und zuverlässige Lösung mit Thyristorstrangreglern
Dauerhaft stabile Spannung in Netzausläufern

von Hans Schmitt & Martin Haseneder



Safely prevent undue voltage increases
Voltage regulator eliminates the need for local grid extension

by Dirk Fuhlbohm, Klaus Kauke





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