Analytical Determination of the Maximum Induced Turn Voltage in the Field Winding of Hydro-Generators During Stator Faults – The Turn-to-Turn Test Voltage

Under normal operating conditions, the voltage between the turns of the field winding of a hydro-generator with salient poles will hardly exceed a few volts and may lead to the wrong and dangerous conclusion that the turn insulation is of no concern. If this voltage is used to design the turn insulation and/or to test it to check and ensure its effectiveness, and/or periodic checks to detect any wear or damage to the insulation, the results may be (very) doubtful. The design will be inappropriate or poor, and tests may only detect a “solid” turn failure.