Parlin Siagian
Universitas Pembangunan Panca Budi, Medan, North Sumatera, Indonesia

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Performance Study of OCR (Over Current Relay) and GFR (Ground Fault Relay) Relays as Protection In 20 Kv Cubicles in Selayang GH PT. PLN UP2D North Sumatra Apda Eriansyah; Parlin Siagian; Rahmaniar Rahmaniar
Jurnal Info Sains : Informatika dan Sains Vol. 16 No. 02 (2026): Info sains, 2026
Publisher : SEAN Institute

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Abstract

Power system protection is crucial for maintaining energy distribution reliability. This study aims to evaluate the performance of Over Current Relay (OCR) and Ground Fault Relay (GFR) as protection systems in 20 kV cubicles at Selayang Switching Station (GH) PT PLN UP2D North Sumatra. The research method used is descriptive quantitative with an engineering case study approach. Data were collected through field observations, short-circuit fault current calculations, and physical testing using the Omicron CMC 353 secondary current injection tool. The results show that the maximum short-circuit fault current of 14.4 kA is still below the circuit breaker's breaking capacity of 16 kA. The pick-up current settings on feeders SLY 05, SLY 06, and SLY 07 met the sensitivity criterion (1.2 x Imax), and the time coordination (grading margin) between protection devices was within the ideal range of 0.25 to 0.5 seconds. Validation through injection testing showed high accuracy with an average operating time deviation of less than 10% according to PLN standards. The conclusion of this study confirms that the protection system at GH Selayang operates efficiently, precisely, and reliably in securing network assets and ensuring the continuity of electricity supply.
Impact of Stator Resistance Unbalance on the Efficiency and Torque of Three-Phase Induction Motor Muhamad Vickry Almuhtadi Billah; Siti Anisah; Parlin Siagian
Jurnal Info Sains : Informatika dan Sains Vol. 16 No. 02 (2026): Info sains, 2026
Publisher : SEAN Institute

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Abstract

Three-phase induction motors are the main components in industrial power systems; However, their performance is vulnerable to internal disturbances such as stator resistance imbalance caused by aging, overheating, or manufacturing defects. This study aims to regularly analyze the impact of stator resistance imbalance on the efficiency and torque characteristics of a squirrel-cage induction motor using mathematical modeling based on an equivalent circuit. Unlike previous studies that employed external resistors, this research directly modifies the stator resistance parameters in the model to represent more realistic internal degradation. Simulations were conducted on a 3.73 kW, 400 V, 50 Hz motor with stator resistance imbalance variations ranging from 0% to 20%. The results show that the imbalance causes uneven current distribution and an increase in stator copper losses of up to 5.94% at the 20% imbalance condition, although the current imbalance percentage remains below 1%. As a result, the efficiency decreases linearly from 92.97% to 92.62%, while the mechanical torque experiences a slight reduction from 95.88 Nm to 95.28 Nm. This phenomenon also has the potential to increase torque ripple and uneven heating. The study demonstrates that even small stator resistance imbalances have a significant impact on motor performance and lifespan, and therefore should be considered in predictive maintenance strategies and energy efficiency optimization.
Efficiency Analysis of A 3-Phase Induction Motor using a Variable Speed Drive as a Speed Controller at PT. Indonesia Asahan Aluminum Muchamad Affan; Parlin Siagian; Dino Erivianto
Jurnal Info Sains : Informatika dan Sains Vol. 16 No. 02 (2026): Info sains, 2026
Publisher : SEAN Institute

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Abstract

This paper analyzes the efficiency performance of a 7.5 kW three-phase induction motor controlled by a Variable Speed ​​Drive (VSD) for industrial speed regulation applications. The motor is rated at 380 V, 50 Hz, four poles, with a nominal speed of 1440 rpm. A constant voltage-to-frequency (V/f) control strategy is implemented with operating frequencies varying from 30 Hz to 50 Hz. Simulation-based analysis is conducted to evaluate electrical input power, mechanical output power, rotational speed, torque, and efficiency under different operating conditions. The results show that the motor input power decreases from approximately 8.0 kW at 50 Hz to 4.0 kW at 30 Hz, indicating significant energy-saving potential during partial-speed operation. Motor efficiency increases with frequency, ranging from 80.0% at 30 Hz to a maximum of 88.8% at the rated frequency. The reduced efficiency at lower frequencies is mainly attributed to the dominance of constant losses such as core and mechanical losses. The study confirms that VSD-based speed control improves operational flexibility and enhances energy efficiency of three-phase induction motors, making it suitable for industrial applications with variable load and speed requirements.