A partial discharge calibration standard apparatus may include a first and second rigid members defining respective first and second facing surfaces. An electrically insulating material may be disposed between the facing surfaces. The apparatus may further include a pressure member maintaining the rigid members together, thereby fixing the first and second facing surfaces in a substantially parallel spaced relation across the insulating material such that a partial discharge threshold magnitude for an electrical potential difference between the first and second facing surfaces is determined. The insulating material may prevent a partial discharge of an electrical potential from the first facing surface to the second facing surface below the partial discharge threshold magnitude, while allowing the electrical potential difference to be discharged from the first facing surface to the second facing surface through the insulating material when the electrical potential difference is increased to the partial discharge threshold magnitude.