ROTATING ELECTRICAL MACHINE WITH MEANS FOR PREVENTING DISCHARGE FROM COIL ENDS

• US 3,670,192 A
• Filed: 10/22/1970
• Issued: 06/13/1972
• Est. Priority Date: 10/29/1969
• Status: Expired due to Term

• Current Assignee: Anders R. Andersson, Lars-Goran Virsberg
• Original Assignee: Anders R. Andersson, Lars-Goran Virsberg
• Inventors: Andersson, Anders R., Virsberg, Lars-Goran
• Primary Examiner(s): Goldberg, E. A.
• Assistant Examiner(s): Witkowski, Stanley J.
• Application Number:
  US05/082,955
• Time in Patent Office: 600 Days
• Field of Search: 310/196 174/12R,127,73R,73SC
• US Class Current: 310/196
• CPC Class Codes: H02K 3/40 for high voltage, e.g. affording protection against corona discharges
• CPC Class Codes: Y10S 174/20 Stator

Abstract

In order to prevent glow discharge from coil ends of a rotating electrical machine to adjacent grounded machine parts, the coil end is provided on the outside of its insulation with a conducting layer which is connected to ground by a voltage dependent impedance, such as a resistance, whose impedance decreases as the voltage increases.

Claims

1. In a rotating electrical machine with a core furnished with winding slots and insulated coil sides disposed in said slots, each coil side having a relatively strongly insulated first portion, substantially located adjacent to a winding slot and a second, relatively weakly insulated coil end portion spaced from the slot, said machine having a grounded part adjacent to said second portion and spaced from the slot end, means for avoiding glow between said second portion and said grounded machine part during high voltage testing comprising a conducting layer on the surface of said second portion, said layer being electrically spaced from the winding slot, and an impedance element connecting said conducting layer to said grounded machine part, the impedance element being voltage-dependent in a voltage range beyond normal machine voltage in such a way that the impedance decreases as the voltage increases.

2. In a machine according to claim 1, said impedance element comprising a resistive member arranged on the outside of the coil surface.

3. In a machine according to claim 1, at least a part of said impedance element comprising a coating having voltage-dependent surface resistivity and arranged on the coil surface between the conducting layer and the end of the winding slot.

4. In a machine according to claim 1, said conducting layer on one coil continuing into a corresponding layer on a following coil in the current direction.

5. In a machine according to claim 1, said conducting layer being joined at its axially outer end to a layer of a resistive material arranged axially outside this layer and on the same coil, said material being voltage-dependent in such a manner that its surface resistivity decreases as the voltage increases.