The objective of the study is to introduce the use of a computer-aided designed high-voltage cell for teaching electrical insulation. The cell allows students to make real applications in high voltage (HV) topics taught in a single-semester course for senior undergraduate students. The system is constituted of two main parts. The first part is a metal cell which consists of a 220V/0-100kV HV transformer, a variable transformer driven by an a.c. motor and a motor driver. The second part is a hand-made electrode system made of tempered glass. The system was controlled manually or automatically using a Programmable Logic Controller (PLC), an operation panel and a computer. In experiments, polyester films are used at various thicknesses as a solid insulation, and transformer oil is also used as a liquid insulation. Each student measures the breakdown voltages under various conditions for solid and liquid insulation using this system. Dielectric strength and ageing of the insulation were determined by computing the mean of the data obtained by each group of students from the experiments. The results and educational benefits are also presented in this paper.