The Haefely VTM 15000 Impulse Transformer for Insulation Testing runs together with a combination wave generator such as PIM 100 or PSURGE 4010. The output voltage of the generator is doubled, the voltage wave shape remains the same. The current wave shape is not defined any more. For insulation testing a VTM 15000 and a combination wave generator can be used. The lightning impulse is the most common impulse shape for testing insulations. No flash over should occur during testing. It is important to keep the load capacitance below the given maximum for having a proper impulse shape at the output of the VTM 15000. When the maximum load capacitance is exceeded one or more impulse parameters may be out of tolerance. The PSURGE 8000 Surge Platform and the PSURGE 4010 combination wave generator provide all the programming functions required to perform IEC, ANSI and UL testing also without the need of a control computer.