DYNAMO ELECTRIC MACHINES INCLUDING ROTOR WINDING EARTH FAULT DETECTOR

• US 3,593,123 A
• Filed: 03/17/1969
• Issued: 07/13/1971
• Est. Priority Date: 03/15/1968
• Status: Expired due to Term

• Current Assignee: Wardle Leonard George, Williamson Alan Charles
• Original Assignee: Wardle Leonard George, Williamson Alan Charles
• Inventors: WILLIAMSON ALAN CHARLES, WARDLE LEONARD GEORGE
• Application Number:
  US04/807,550
• Time in Patent Office: 848 Days
• US Class Current: 324/545
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: H02K 19/36 Structural association of synchronous generators with auxiliary electric devices influencing the characteristic of the generator or controlling the generator, e.g. with impedances or switches
• CPC Class Codes: Y10S 174/15 in a power generation system, e.g. prime-mover dynamo, generator system

Abstract

A dynamo electric machine having a rotor with a field winding energized by a rotatable rectifier network is provided with a transformer the secondary winding of which rotates with the rotor and the primary winding is stationary. In conjunction with ancillary apparatus this enables a flow of fault current between the rotor winding and rotor body to be detected by consequent changes in an electrical quantity at the stationary primary winding.

Claims

1. A dynamo electric machine having a stator structure and a rotor structure, a direct current field winding carried by the rotor structure, a rotatable rectifier network mounted on the rotor structure for energizing the rotor winding with direct current, and an earth fault detector for the rotor winding including:

a transformer having a primary winding and a secondary winding, the primary winding being mounted on the stator structure, the secondary winding being mounted on the rotor structure so as to be rotatable therewith, means for energizing the transformer primary winding with alternating current, a second rectifier mounted on the rotor structure, means for connecting the second rectifier to the rotor winding, the rotor structure, and to the transformer secondary winding so that, with the primary winding energized, a direct current voltage is impressed across the rotor winding and the rotor structure, and detector means for detecting a change in an electrical quantity at the said primary winding resulting from an earth fault between the rotor winding and the rotor structure which causes current to flow through the second rectifier and the transformer secondary winding.

2. A dynamo electric machine according to claim 1 including, a current-limiting resistor connected between the second rectifier and the rotor winding.

3. A dynamo electric machine according to claim 1 in which the detector means includes, a capacitor connected across the transformer primary winding, and a capacitor connected across the transformer secondary winding, these capacitors acting to tune the transformer windings so that the primary winding has a purely resistive impedance, and means for detecting a change in the resistive impedance of the said primary winding.

4. A dynamo electric machine according to claim 3 in which, the transformer primary winding and its associated capacitor are connected as one arm of a bridge network which comprises, the said primary winding and capacitor in one arm, a resistive arm, a pair of like reactive arms, and a detector device connected across the junction of the primary winding arm with the resistive arm and the junction of the pair of reactive arms, the alternating current input to the transformer being applied across the other two opposite diagonal junctions of the bridge arms.