Westinghouse Electric Corporation

Dale I Gorden

Sigrud R Petersen

Robert C Miller

Lee A Kilgore

Eugene C Whitney

Leonard W Finnell

Arthur H Hoffmann

A method and arrangement of apparatus is provided for remotely and selectively determining the existence of a failed fuse in the rectifier circuit of a brushless exciter rotor. A current transformer is disposed about each fuse in such a way that uses the conductor which carries current to the fuse as the primary winding of the current transformer. A light emitting diode is connected in series with the secondary winding of the current transformer. The emitted light, indicating a current flow through the fuse, is sensed by a stationary photodetector. This method senses the existence of a current flow through the exciter fuses and thereby positively determines each fuse that has not failed. Electronic circuitry is used to synchronize the detection operation with the rotation of the brushless exciter rotor so that each fuse is inspected at a time when it is expected to be carrying its maximum current. Since this method looks for the existence of current through each fuse, it operates in a failsafe manner.

Failed fuse detector and detecting method for rotating electrical

For a dynamoelectric machine, excitation power is supplied by a main exciter having two field windings. A first field winding is driven by a pilot exciter which supplies base excitation (small signal) for the main exciter. Forcing excitation (large signal) is supplied by the second field winding which is driven by an external, supplemental power source. The main exciter can thus provide the appropriate excitation for both normal and transient operating conditions. In addition, by switching the controlled rectifier elements associated with the supplemental power source, the second field winding is also capable of providing fast de-excitation for the main exciter.

Dynamoelectric machines brushless supplemental excitation system

A brushless excitation system for a synchronous dynamoelectric machine includes an alternating current exciter and a rotating rectifier assembly. In such a system, the alternating current exciter includes a salient pole stator field member and a polyphase armature rotor member. A sensing coil is disposed around at least one of the salient stator poles for developing an alternating electrical signal in response to changes in the magnetic flux wave linking the rotating armature member and the field coil of the salient stator pole member. Means connected to the sensing coil indicates variations in the alternating current signal which correspond with disturbances in the rotary electric circuit of the brushless exciter such as a line-to-line short circuit or a phase-to-phase short circuit in the armature winding, or shorted diodes or open fuses in the rotating rectifier assembly.

Brushless exciter fault indicator system

Thyristors are substituted for conventional diodes in the rotating rectifier assembly of a brushless exciter in a synchronous dynamoelectric machine. In contrast with prior systems in which thyristors are switched at relatively high ceiling voltages (requiring thyristors of high power rating and additional components for fast de-excitation), the gates of the thyristors in the present invention are fired only at a low voltage point of the negative half cycle of the polyphase armature voltage waveforms for fast de-excitation and are maintained in a fully conducting condition during the positive half cycle. This permits the use of thyristors having a relatively lower power rating and makes unnecessary additional components to achieve fast de-excitation.

Fast de-excitation brushless exciter

Method and apparatus for accelerating a large inertia load from rest to a predetermined speed of rotation by means of a synchronous dynamoelectric machine. A synchronous dynamoelectric machine, such as a turbine generator, which is mechanically coupled to a gas turbine prime mover, is started synchronously to bring the gas turbine up to a speed which exceeds its stall speed under load. The rotor field winding of the synchronous dynamoelectric machine is connected to receive direct current excitation from a rotatable rectifier assembly of a brushless exciter. During starting, a quadrature axis winding disposed around the stator of the brushless exciter is energized by single phase alternating current. Alternating current excitation is induced by transformer action within the rotor armature winding of the exciter and is applied to the rotor field winding after being rectified by the rotatable rectifier assembly. The transformer action operates independently of the rotation of the rotor member of the synchronous dynamoelectric machine so that the brushless exciter develops direct current field excitation for starting purposes when the rotor is at rest. Polyphase alternating current excitation is applied to the synchronous dynamoelectric machine stator winding to establish a dynamic magnetic field which rotates at a speed proportional to the frequency of the applied excitation. Interaction of the static magnetic field of the rotor and the rotating stator field produces the mechanical turning force. The frequency of the synchronously applied stator excitation is increased from substantially zero cycles per second to a higher frequency until the rotor member has accelerated synchronously to the desired speed of rotation.

Quadrature axis field brushless exciter

An excitation system for a synchronous generator includes a conventional brushless exciter for providing base excitation for rated power output and a controlled source of direct current interconnected with the conventional brushless excitation system to supplement the base excitation. The supplementary excitation is supplied to the rotating field winding of the synchronous generator to provide forcing excitation to permit operation of the generator at power levels which exceed the generator's base power output level. In a preferred embodiment of the present invention, means operable to derive a control signal proportional to a predetermined function of the field winding excitation and of the power output of the generator is provided to control the magnitude and polarity of the supplemental excitation to permit operation of the synchronous generator at power levels which exceed its base power output level, to provide negative direct current excitation to permit fast-de-excitation of the generator, and to provide substantially zero supplemental excitation when the generator is operating at its base power output level.

Brushless exciter supplemental ceiling excitation system

In a synchronous dynamoelectric machine having a pilot exciter which energizes a brushless exciter, voltage regulation and forcing excitation are provided by a plurality of field coils which are disposed upon selected ones of a plurality of permanent magnets carried by the rotor of the pilot exciter. The field coils are connected together to constitute a field winding and are electrically connected to receive direct current excitation from the output of a rotating rectifier assembly through coupling means, such as a direct current regulator. In operation, the regulator is responsive to changes in the current flowing through the field winding of the synchronous dynamoelectric machine and provides a direct current output signal to the permanent magnet field winding to increase the magnetic field strength of the associated permanent magnets.

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North Versailles, PA, United States of America

Dale I Gorden