This ControGen HX static excitation system is manufactured by General Electric and designed to supply the field of the generator with a DC current. The excitation power needed is supplied from generator bus bars by means of the existing power potential transformer and a thyristor rectifier system. We are offering this to you in Brand New condition, packed and ready to ship. There is only one unit available.



AC and DC power connections and other interfaces of the excitation cubicle have been considered. If some minor modifications are identified during the design phase of the project, they will be communicated to the customer at early stage.


The proposed excitation system is defined according to the specific operating conditions and project technical requirements:


Rated field voltage (UfN)

220 V

Rated field current (IfN)

1412 A

Maximum continuous Excitation current (IfD)

1590 A (1.1pu)

Ceiling field voltage (UfP)

496 V

Ceiling field current (IfP)

3180 A

Ceiling duration

10 sec

It is designed for the following continuous operating conditions:
Maximum ambient temperature : 40°C inside the air-conditioned container (up to 55°C

inside panel).
Humidity range : 5-85% (air-conditioning system should permit to dry the

ait inside the container).
Altitude (above sea level) : less than 1 000m.

The system is able to:

  • Reverse the excitation voltage to full negative ceiling voltage to reduce quickly the

    generator field current.

  • Operate at ceiling current during 10 seconds maximum, up to 4 times per hour.

    4 EXCITATION TRANSFORMER (out of scope)

    The existing excitation transformer will be kept.


One cubicle including:

  • Rectifier part

  • Field switch part (including Crowbar)

  • Protective relays part

  • AVR part

    5.1. Rectifier part

    Two (2) three-phase, fully controlled, thyristor bridges are connected in parallel for 100% redundancy. In case of failure of one rectifier bridge (N-1mode), the other one can supply the maximum rated and ceiling excitation values.

The rectifier bridges have the following features:

  • The thyristors as well as the fast-acting fuses, mounted on heat sinks, are designed for easy removal and replacement.

  • The thyristors can withstand, at full operating temperature, a repetitive blocking voltage not less than 2.7 times the peak voltage.

  • A current limiting fast-acting fuse is provided in each thyristor leg to isolate the circuit and protect other thyristors and their fuses from damage if a thyristor fails.

  • Forced-air cooling fan system. Fan failure is monitored on the LCP panel.

  • Supervision of fuses blowing by mechanical indicators (micro-switches NO); the alarm

    of this failure is monitored on the LCP panel.

  • Overvoltage protective circuits are included to protect the equipment from transient overvoltages originating in the AC system and in the field circuit (snubber circuits).

  • Low voltage control equipment is shielded and isolated from AC and DC power circuits.

  • A set of temperature sensors (thermos-switches or similar) for alarm, trip and

    monitoring on the LCP panel.

  • Each rectifier bridge is equipped with a 5 poles disconnecting switch (2DC and 3AC poles) in order to allow access to the whole rectifier bridge for inspection and maintenance operation during operation of the unit.

    5.2. Field circuit breaker and DC part

    The following elements are included:

  • One (1) two poles generator field circuit breaker, with field discharge NC contact and auxiliary NO-NC position contacts. This breaker is provided with arc-extinguishers and the operating mechanism is electric with mechanical latching and two tripping coils. This breaker is able to interrupt the field circuit successfully under maximum current and voltage conditions. The contacts have easy access for inspection and replacement.

  • A field discharge resistor, linear type, calculated to discharge the energy stored in the generator field from the ceiling current after tripping of the field breaker, it is inserted either through the discharge Crowbar, on normal shunt down or through the Crowbar in case of over voltage – in both cases the bridge is controlled in inverter mode before opening the breaker.

  • A field over voltage device named “Crowbar” associated with the field discharge resistor above, limits the overvoltage induced in the rotor due to negative currents on transfers occurring in fault conditions.

  • DC field polarity switch to change the field voltage polarity during maintenance.

  • DC field flashing circuit (field breaker, flashing diode, too long flashing monitoring).

  • One calibrated shunt.

  • CT’s give excitation current measurement to each regulator.

  • Auxiliary transformers for regulator and thyristors firing devices.

  • A heating (anti condensing) resistor with its temperature control will be fitted in each cabinet.

  • Lighting controlled by doors contact; maintenance power supply socket.

• PT’s and Ct’s circuit test switches

ControGen HX Static Excitation System General Electric



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