Context:

For years, the safe and effective measurement of high voltage signals has one of the major concerns of those conducting high voltage tests; in these cases, voltage divider represents one of the most important devices for laboratory measurement of signals (such as those generated by lightning). However, the divider must have adequate characteristics of nominal voltage, scale factor, and frequency response, so that the recorded signal is a reflection of the signal applied to the equipment under test. For example, the most commonly developed voltage dividers (resistive divider, capacitive divider, and damped capacitive divider) have their own characteristics that allow a good performance of the high voltage measurement and recording system. This paper presents the theoretical and practical aspects related to design, construction, and evaluation of a damped capacitive divider of 300 kV in order to evaluate the performance of the measurement and recording system in relation to the conversion stage.

Method:

Simulation tools such as MATHEMATICA® and PSPICE® were used for the design and evaluation of the voltage divider. These helped estimate the behavior of the divider components (damping resistor and low voltage arms). Additionally, laboratory equipment (frequency response meter and 300 kV voltage pulse generator) was used to verify the performance of the components. The experiments were based on frequency response tests, insulation capacity, and obtaining the scale factors according to national and international standards.

Results:

In the frequency response test performed on the damping resistor from 20 Hz to 1 MHz, the parasitic effects are negligible and the impedance of the resistor can be considered purely resistive. In the insulation capacity test, resistor can withstand voltage pulses of up to 10 kV without breaking the resistor insulation. Regarding the verification of the scale factors, the porcentage differences did not exceed the limit of peak voltage variation set by the standard.

Conclusions:

The results show the methodology developed was adequate for the design, construction, and simulation of the voltage divider. The electrical models suggested in the methodology were sufficient to obtain reliable results during simulations. Finally, the most important contributions of this work were the construction of a non-inductive damping resistor and the construction of an additional low-voltage branch.