Initially, an automatic voltage regulator (AVR) for generators was an electro-mechanical device with a variable resistance as an output. Generators with a dc exciter were often provided with the Brown Boveri (BBC) Universal Voltage Regulator.
After the development of the power electronics, electronic voltage regulators with one or more thyristors became available. For power factor of VAR control, limiters, diode fault detection and / or protection separate modules were used.
In the 90 manufacturers bring the first digital voltage regulators on the market. These controllers contain more integrated features, but for many features separate modules are still required. The modern, state-of-the-art integrated systems do not only contain automatic voltage control, but moreover an extended functionality.
The Brown Boveri Company (BBC, now ABB) electro-mechanical Universal Voltage Regulator was widely used for generators with a dc exciter.
A number of voltage regulator manufacturers are given below.
Brush Prismic type A12 and A32 are modern, multifunctional excitation controllers, suitable for generators with brushless excitation and a PMG. For static exciters and other excitation systems Brush provides the Prismic A50. Precursors are the A10 (digital), A30 and MicroAVR (both partly digital) and the MAVR (analog). PEAVR, STAVR, BAVR and TDES AVR are electronic models that Brush BEM in Engeland manufactured in the past. Brush HMA (formerly Holec Ridderkerk, Smit Slikkerveer) had the electronic regulator ESR-2.
Basler Electric type DECS 200, DECS 200N and DECS 250 are modern, multifunctional excitation controllers, suitable for generators with brushless excitation and a PMG. For static exciters and other excitation systems Basler provides among others the DECS 400 and the new DECS 2100. Basler still provides analog regulators from the AVC, SR, SSR and VR Series. Among others the digital DECS 15 and analog XR2002 are obsolete.
ABB Unitrol type 1020 is one of the multifunctional excitation controllers, that is suitable for generators with brushless excitation and a PMG. For statische exciters ABB provides the Unitrol 6000. The digital Unitrol F and the analog Unitrol M were the precursors.
GE Energy type EX 2100e is GE’s most modern, multifunctional excitation controller, suitable for among others generators with brushless excitation and a PMG, but also for static exciters and other excitation systems. The control loops are identical, but the power converter is adapted. Precursors are among others the EX2100 and the EX 2000 (both digital).
GEC Alsthom type DX21 (digital) and the C10/120 (electronic) are developed for generators with brushless excitation. Separate modules as the MC15 (Manual Control), FV200 (Excitation Fault Detector), FV223 (Diode Failure Detector), FF100 (VT Fuse Failure Detector) and LC110 (Limiter and PF/VAR Control) were often added.
EMRI from Ede (NL) develops and produces universal, often analog voltage regulators and control- and protection electronics, in order to replace components from older electronic, modular assembled control systems.
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