The reliability of the Electric Power Network is a demand of modern society
today. Various programs to improve reliability are carried out, including inspection
and maintenance of distribution substations. Inspections are carried out periodically
to determine the condition of the equipment functioning properly. However, there
are still disturbances caused by the corona in the 20 kV cubicle. The impact is the
interruption of electricity supply to customers and the potential to cause damage to
the cubicle itself. This research is related to the design of a corona detector
prototype as a cubicle protection output of 20 kV. The method used includes
requirements analysis, design planning, assembly and system testing. The prototype
tool measures the concentration of ozone (O3), temperature and humidity in the
cubicle. The test parameters include the effect of humidity and the amount of stress
on the formation of the O3 concentration. The humidity effect test results as follows: humidity 99% RH amount 03: 241.0 ppb., Humidity 95% RH amount O3: 106.2 ppb and 90% RH amount 03: 78.55 ppb. The voltage effect test results are as follows: 14V voltage of O3: 225.36 ppb, and 12V voltage of O3: 106.63 ppb. When
the O3 measurement has reached the set value, the Microcontroller is ordered to
activate Digital Output. Based on the test results, the prototype of the corona detector can be used as cubicle protection for the 20 kV output of medium voltage
customers.
Key words: corona, Ozone, humidity