HYDRO has developed its own voltage regulator to manage the reactive power of synchronous machines. HEXita has already seen successful use on three machines, and other projects are underway.

The excitation system in a hydroelectric set assumes a crucial role: it monitors the operation of the synchronous machine and keeps it within acceptable limits. More precisely, it regulates its voltage and reactive power.

HYDRO has developed its own regulator, HEXita, to provide greater flexibility at a very competitive price. It comes with all the usual functions of a voltage regulator, including various regulation modes with limiters, protection features, monitoring of rotating diodes, all synchronisation modes, and communication ports via bus and/or wired inputs/outputs for interfacing with the control system. 

Independence from suppliers

HEXita can also drive different types of power semiconductors (low-cost IGBTs or high-performance thyristors), so it can adapt to almost any excitation current. Finally, by using commercially available electrical components, HEXita gives us enhanced autonomy and independence from suppliers.

HEXita has already been installed on an auxiliary set (870 kW) with direct excitation (rated current 76 A) and on two 11.6 MVA alternators with indirect excitation (rated current 12 A), and numerous machines are currently undergoing modification.


HYDRO Exploitation SA
Rue de l’Industrie 10
CP 315 - CH-1951 Sion
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HYDRO Exploitation SA
Rue de l’Industrie 10 CP 750 - CH-1951 Sion +41 (0)27 328 44 11
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