DIELEKTRIKA

Sistem Presensi Mahasiswa Berbasis Android dengan Biometrik Wajah Menggunakan FaceNet dan Pembatasan Lokasi Berbasis GPS

2026-02-23T14:05:08+08:00

Student attendance is essential in academic activities, yet conventional methods are prone to fraud, errors, and inefficiency. This study develops an Android-based attendance system integrating face recognition using FaceNet and GPS-based location validation within a client–server architecture. The system performs facial embedding extraction and identity verification using Cosine Similarity with a threshold of 0.7, while geofencing ensures valid attendance locations. Testing on 20 students shows an accuracy of 87.14%, precision of 100%, recall of 83%, and an F-score of 90.71%. GPS validation achieves 100% accuracy within a 10-meter radius. Robustness testing demonstrates stable performance under normal conditions and facial expression variations, with decreased performance under occlusions, extreme lighting, and motion. The system achieves an average processing time of 38.12 ms, indicating fast and responsive performance. These results show that the proposed system improves the accuracy, security, efficiency, and robustness of student attendance management.

Evaluasi dan Optimasi Kinerja Pembangkit Listrik Tenaga Surya Off-Grid pada Aplikasi Pompa AC 125W untuk Irigasi Nyayur

2026-02-18T16:09:22+08:00

Sistem Pembangkit Listrik Tenaga Surya (PLTS) off-grid banyak digunakan pada aplikasi pompa air berdaya rendah, namun kinerjanya sangat dipengaruhi oleh kesesuaian kapasitas komponen terhadap karakteristik beban. Pompa air AC sebagai beban induktif memerlukan arus start tinggi yang dapat menurunkan stabilitas sistem. Penelitian ini bertujuan untuk mengevaluasi dan mengoptimasi kinerja sistem PLTS off-grid pada aplikasi pompa air AC berdaya 125 W.

Sistem awal terdiri dari panel surya 300 Wp, solar charge controller (SCC) 10 A, baterai 12 V 50 Ah, dan inverter 500 W. Hasil evaluasi menunjukkan terjadinya pembatasan arus pengisian oleh SCC serta penurunan tegangan baterai yang signifikan saat pompa beroperasi. Optimasi dilakukan dengan meningkatkan kapasitas SCC menjadi 30 A, baterai menjadi 12 V 100 Ah, dan inverter menjadi 1000 W. Evaluasi performa dilakukan melalui pengukuran tegangan, arus, dan state of charge (SOC) baterai. Hasil menunjukkan peningkatan stabilitas tegangan, pengisian baterai yang lebih optimal, serta penurunan SOC yang lebih lambat, sehingga sistem menjadi lebih andal dan stabil.

Dynamic and Stability Assessment of an Automatic Voltage Regulator Based on Time- and Frequency-Domain Analysis

2026-02-25T09:00:01+08:00

This study presents a dynamic and stability analysis of an Automatic Voltage Regulator (AVR) system for a synchronous generator using time-domain and frequency-domain approaches. The system is modelled as a series of first-order linear subsystems consisting of an amplifier, exciter, generator, and feedback sensor, resulting in a fourth-order closed-loop system. Numerical simulations are conducted to compare the performance of the AVR without a controller and with a PID controller. Time-domain analysis indicates that the uncontrolled system exhibits a rise time of 0.339 s, an overshoot of 57.937%, and a damping ratio of approximately 0.17, indicating a heavily underdamped response. After implementing the PID controller, the rise time decreases to 0.295 s and the overshoot is significantly reduced to 14.368%, with the damping ratio increasing to approximately 0.53.

Frequency-domain analysis using Bode diagrams shows an improvement in phase margin from less than 20° to more than 40°, and gain margin from below 6 dB to above 10 dB. The dominant pole shifts from approximately Re(s) ≈ −0.2 to Re(s) ≈ −1.0 in the complex plane, confirming enhanced relative stability and faster transient decay. Overall, the results demonstrate that the PID controller significantly improves stability, response speed, and damping performance, making it suitable for voltage regulation in power system applications

Analisis Pengaruh Variasi Faktor Daya terhadap Efisiensi dan Regulasi Tegangan Transformator Distribusi Tiga Fasa 240 kVA Menggunakan MATLAB

2026-03-01T16:19:01+08:00

Power factor is one of the key parameters affecting the performance of distribution transformers, particularly in terms of efficiency and voltage regulation. This study aims to analyze the effect of power factor variations on the efficiency and voltage regulation of a 240 kVA three-phase distribution transformer using MATLAB simulation. The power factor was varied from 0.8 lagging to 0.8 leading under the assumption of constant load power, allowing quantitative observation of performance changes. The simulation results show that the maximum efficiency of 98.334% is achieved at unity power factor (cos φ = 1). When the power factor decreases to 0.8, the efficiency drops to 97.927% for both lagging and leading conditions. This efficiency reduction is caused by the increase in load current as the cos φ value decreases, which leads to higher copper losses (I²R). Although the decrease in efficiency is relatively small, its impact can become significant in long-term operation. On the other hand, voltage regulation exhibits different trends under lagging and leading conditions. At 0.8 lagging power factor, the voltage regulation reaches 3.152% and decreases to 1.163% at unity power factor. Under leading conditions, the regulation becomes negative, reaching −1.307% at 0.8 power factor, indicating a voltage rise due to the dominance of the transformer’s reactance component. Overall, operating the transformer at a power factor close to unity provides the most optimal performance in terms of efficiency and voltage stability, and it is essential in planning reactive power compensation in power distribution systems.

Pengaruh Kombinasi Jumlah Slot Stator - Kutub Magnet Rotor pada Unjuk Kerja Motor BLDC

2026-03-04T14:46:10+08:00

Pemilihan jumlah slot stator dan jumlah kutub magnet rotor adalah hal yang sangat penting dalam perancangan sebuah motor BLDC karena kedua parameter tersebut secara langsung mempengaruhi performansi elektromagnetik, karakteristik torsi dan efesiensi. Kombinasi slot-kutub yang tidak sesuai dapat memicu peningkatan riak torsi (torgue ripple), coging torsi (cogging torque), rugi-rugi inti maupun rugi-rugi tembaga dan pada akhirnya dapat menurunkan performa dari motor. Paper ini menyelidiki pengaruh jumlah slot dan kutub terhadap unjuk kerja motor BLDC. Penyelidikan dilakukan dengan memodelkan motor BLDC dengan diameter luar stator, lebar airgap dan material magnet yang identik dengan beberapa kombinasi slot-kutub yakni 18/4, 18/8, 18/12 dan 24/22. Hasil investigasi mengkonfirmasi bahwa pertambahan jumlah kutub dari 4, 8 dan 12 pada jumlah slot tetap (18) meningkatkan magnitude, ripple dan coging torsi. Hasil ekperimen juga menemukan bahwa kombinasi slot-kutub (24/22) merupakan kombinasi terbaik dimana ripple torsi dan coging torsi menjadi sangat kecil dan halus. Semantara itu pengaruh kombinasi slot-kutub terhadap rugi-rugi memperlihatkan bahwa pertambahan jumlah kutub meningkatkan rugi-rugi besi dan rugi tembaga karena ketika kutub bertambah maka kecepatan motor akan menurun. Jika kecepatan sinkron menurun (untuk daya yang sama), maka arus akan meningkat sehingga rugi tembaga bisa meningkat pada motor dalam kondisi low-speed high-torque.

Analisis Kondisi Transfomator Berdasarkan Persentase Kandungan Gas Terlarut dan BreakDown Voltage Minyak Transfomator di PT X

2026-03-02T15:00:32+08:00

Transformator berperan penting dalam sistem tenaga listrik, dan keandalan minyak isolasi perlu dipantau melalui pengujian Dissolved Gas Analysis (DGA) serta Breakdown Voltage (BDV) untuk mencegah gangguan. Penelitian ini bertujuan untuk mengetahui kondisi transformator 1500 kVA unit 50-TL-EP741 di PT X berdasarkan hasil uji DGA dan BDV. Pengujian DGA menggunakan alat Transport X dengan metode Total Dissolved Combustible Gas (TDCG), Key Gas, Roger’s Ratio, dan Segitiga Duval mengacu pada IEEE C57.104-2019, sedangkan BDV diuji dengan alat Megger tipe OTS80AF berdasarkan IEC 60156-2018. Hasil pengujian DGA menunjukkan peningkatan gas etilena (C₂H₄) dan hidrogen (H₂) yang menandakan gangguan termal ringan, sementara nilai BDV 52,7 kV/2,5 mm menunjukkan minyak masih dalam kondisi baik. Kondisi transformator masih layak operasi dengan indikasi degradasi awal sehingga perlu pemantauan berkala.