Image source: Haefely

Haefely patented Series Overshoot Compensation

The Series Overshoot Compensation is a HAEFELY patented additional circuit for impulse generators. This additional feature can be added later to an existing impulse generator, even on non Haefely models. The overshoot compensation consists principally of and additional compensating capacitor, a compensating inductive resistor in parallel to the capacitor and a supporting structure with castors.

With the overshoot compensation the capacitive load range can be extended up to two or three times more than the standard range (for the 1.2/50 LI impulse shape).

Therefore, it is highly recommended for testing large capacitive loads (power transformers, cables, etc.). The OC circuit cannot be used to suppress reflections caused by transformer windings.

Source: Haefely