This paper presents the construction of a Rogowski Coil sensor with an air core to detect partial discharge using a digital oscilloscope. Two types of sensors are used. The first is the primary sensor winding with back wire, and the second is without back wire, labeled BW and WBW, respectively. The numbers of primary-turn in the sensors are 5, 10, 20, and 40 turns. The performance of the sensors is tested using two types of tests. First, the wave response test with a fixed imitation partial discharge magnitude input is used to select the optimum sensitivity with the lower sampling rate, aims to select the peak or valley value as a magnitude partial discharge value. The second test is using an imitation partial discharge ramp to check the linearity of the sensors. The imitation of the partial discharge inputs is generated by a commercial charge calibrator. The wave response test results show an increase in the number of turns that corresponds to an increase of the sensor output for both sensors in a non-linear trend. In determining the sampling rate, the detection of magnitude in the valley is better than the peak. All sensors act linear toward the imitation partial discharge ramp either in BW or WBW conditions.

BACKGROUND: Corncob is one of crude drug which containing phenolic compounds that can be used as an active ingredient for sunscreen preparations. In this study, extracts of dried corn cob made into a gel formulation using SRC (Semi Refined Carrageenan) and glucomannan as a gelling agent. AIM: This study aims to determine the optimal concentration of SRC (Semi Refined Carrageenan) and glucomannan to the physical stability of the gel. METHODS: Gel made into four formulas with a ratio of 1: 4 and the concentration of each formula was 1%, 1.5%, 2%, 2.5%. Each formula was evaluated for 6 weeks of storage that includes organoleptic test, homogeneity, pH, viscosity, dispersive power, freeze-thaw test and centrifugation. RESULTS: The results showed the fourth formula did not change the organoleptic test and homogeneity test. In the test separation of the freeze-thaw method, the fourth formula was stable, while in the centrifugation test formula 1 and 2 was been separation. pH and viscosity results obtained from statistics with a two-way ANOVA showed significant differences in each formula. CONCLUSION: From the results of this study concluded that the formula 3 with a concentration of 2% was the optimal concentration as a gelling agent.

Partial Discharge is one of the phenomena that occurs in the electric power system, which is characterized by the phenomenon of heat which will disrupt the insulation system. If this phenomenon is left for a long time, it will disrupt the process of distributing electricity, even stopping the process of distributing electricity. Partial discharge testing can be tested in 2 ways, namely conventional using coupling and conventional using electromagnetic methods, optical methods, acoustic methods, and chemical methods. Moisture testing in part in this study uses a non-conventional method with the electromagnetic method. The electromagnetic method used is the Rogowski Coil with ferrite and non-ferrite cores. Each Rogowski Coil core has an inner diameter of 1.2 cm, an outer diameter of 2.5 cm, a height of 2.5 cm and a total of 10 turns. The results of the partial sweat test show that the non-ferrite core Rogowski Coil responds faster than the ferrite core Rogowski Coil. As for the sensitivity level of the second core used for partial discharge testing, it can be seen that the Rogowski Coil with a ferrite core is more sensitive than the non-ferrite core with a sensitivity value of 11.63%.

The Rogowski Coil sensor is one of the sensors used to detect aging insulation, which is marked by the occurrence of Partial Discharge. Aging is damaged, which fails power tools when operated. If the insulation is aging and even causing damage, the distribution of electrical energy will be disrupted. This research presents two types of Rogowski Coil sensor core materials to detect Partial Discharge with the same number of turns. The number of turns is 5. The first sensor is a sensor with a ferromagnetic core and the second sensor is a sensor with a non ferromagnetic core. The test of the sensor is carried out by using a magnitude test using a charge calibrator as an imitation of Partial Discharge. The magnitude of the Partial Discharge read by the sensor uses a digital oscilloscope with an impedance of 50 Ohm. Measurement results compared to commercial sensors. The measurement results read by the oscilloscope found that the type of sensor core influences the magnitude value of Partial Discharge. The magnitude of the Partial Discharge sensor with a ferromagnetic core is greater than that of a sensor with a non ferromagnetic core. However, both results are much smaller than the commercial sensor even though the digital oscilloscope can read them.

Partial-discharge is a symptom of high voltage insulation aging, which is a small voltage pulse with high frequency and superposition with high voltage sources that have low frequencies. To find out the existence of this signal, it needs a reliable measurement technique to avoid misinterpretation. This paper presents a technique for measuring partial discharge with an induction method. The sensor used is circular twin loops. The first loop passes through a partial discharge signal, and the second induction receiver produces an induced voltage signal. Various sizes of loop diameters are designed with dimensions 3.2, 4.7, 8.9, and 11.4 cm to look for sensor sensitivity. The performance sensor is analyzed by reading the sensitivity test to the input given with 50-ohm oscilloscope impedance. From the measurement results, the higher the diameter of the sensor loop has good sensitivity.