The UNITROL 5000 is designed as a modular “building-block system”. More than 80 % of all systems can be made from type-tested system components.
This guarantees higher quality and makes shorter delivery times possible. The power section consists of one or more thyristor power converters, field breaker on the AC or DC side, the field flashing circuit and the solid state de-excitation system with Crowbar.

High availability due to the additional backup current regulator
To further increase the availability of the excitation system, in addition to the voltage regulator (AUTO) and the excitation current regulator (MAN), an independent current regulator (separate device with power supply, measurement and gate control circuits) can be used. Because of the follow-up control for all the inactive regulators, in the case of failure of the active regulator a smooth switch-over to a ready-to-operate regulator channel is guaranteed.

Less wiring thanks to the internal ARCnet® field bus
The exchange of data within the system, e.g. between the voltage regulator, power components and interface devices takes place via the serial ARCnet bus.
Additional interfaces or control panels can be located and operated up to a distance of several 1000 m via an optical link. Powerful and reliable power converters
Either compact power converters of the DCS 500 series or type UNL 13300 or Verithyr power converters are used for the UNITROL 5000. The type and the number of parallel power converters are based on the required field current, the ceiling voltage and the maximum dutycycle required by the customer.
The following options are available:
• Natural or forced cooling
• Redundant fans
• Possibility to do maintenance work on one power converter during the operation of the system (with 5-pole isolator).

Application function blocks
In addition to the standard softwarefunctions, further universally applicablefunction blocks of various kinds areavailable for the application program.These are tested application proceduressuch as input/output extensions, specificmonitoring functions, etc.
Power System Stabilizer (PSS)
The purpose of the power system stabi.lizer is to improve the stability of thegenerator and the transmission systemas a whole by using the excitation todamp load oscillations. The PSS operatesby influencing the input of the voltageregulator-extremely effective withstatic excitation systems, but also effectivefor systems with rotating exciter.
ABB offers three different types ofpower system stabilizer:
PSS in accordance with lEEE
For the stabilizer in accordance withIEEE -PSS2A, fixed parameters take careof optimum damping with adjustablelead/lag filters. To determine theseparameters ABB has calculation softwarethat takes account of the generator andexcitation system data, as well as thetransformer and network reactances.