The protection of many low and medium voltage equipments is very important because of their value and function. It's not just about safeguarding, but also avoiding faults resulting from extreme stress. The main cause of this stress is overvoltage or overcurrent. These can destroy the wires, insulations and the whole equipment, causing very high expenses to the owners. Overcurrent protection can be found everywhere, even in homes in the form of circuit breakers and fuses. Overvoltage protection, however is applied only by high value equipments such as low voltage computer centres or medium voltage transformers. In these cases the price of the protection can be compared to the price of the protected equipments. That's why the proper and reliable functionality is very important of the protecting equipments. To verify this, testing is needed according to the standards. Since the source of the overvoltage is mostly a lightning strike, the standards set the waveforms and values of the test current impulse. In this thesis, the test of a medium voltage overvoltage protection equipment will be presented, starting with the review of the special current impulse generator, through a simulation for tuning the parameters of the generator to the actual measurement.