Electric field analysis results have shown that typical motor winding connecting cables can, even at modest operating voltages, produce electric field stresses likely to cause partial discharges. Experimental results verified this prediction. Further electric field analysis and experimental results indicated that this partial discharge problem could be virtually eliminated by separation of the cables and by placing them on a thin insulating support. Very approximate calculations have indicated that when motor winding connecting cables are placed in direct contact with the motor frame, partial discharge magnitudes could reach dangerous levels and be a possible source of ignition of incendive atmospheres.
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