STL Modul 3 Pengujian Tahanan Isolasi

Summary

In this practical session on insulation resistance testing, the focus is on measuring the insulation resistance of a distribution transformer. The process includes using an insulation tester to check the resistance between various sections: low voltage (TR), medium voltage (TM), and the body. The procedure involves injecting a 5,000V DC voltage, recording resistance values at the first and tenth minute, and calculating the polarization index to assess the insulation condition. The test results show good resistance values, indicating that the transformer’s insulation is in good condition. The session concludes with a reminder to restore equipment and ensure safety.

Takeaways

• 😀 The practicum focuses on insulation resistance testing for electrical equipment, specifically transformers.
• 😀 The testing is conducted using an insulation tester, which is connected to the Earth and Line terminals.
• 😀 Insulation resistance is measured between different sections of the transformer: low voltage (TR) and body, medium voltage (TM) and body, and medium to low voltage.
• 😀 The testing tool (insulation tester) has a maximum voltage of 5000V DC, which is used to inject a test voltage into the transformer.
• 😀 The polarization index (PI) is calculated by comparing the resistance values at the first and 10th minute of testing.
• 😀 A PI value between 1.6 and 2.0 indicates good insulation resistance, meaning the transformer is in good condition.
• 😀 For each test, the first minute of resistance is measured, followed by the 10th minute to determine the PI.
• 😀 The insulation resistance testing involves setting the tester for 10-minute intervals, ensuring that the voltage is stable during the test.
• 😀 After completing the measurements for all transformer sections, the insulation tester is returned to its original settings and disconnected.
• 😀 The purpose of the test is to determine the insulation resistance values of different transformer sections and ensure the equipment's safety and reliability.

Q & A

What is the purpose of the insulation resistance testing in this practicum?

The purpose of the insulation resistance testing is to determine the insulation resistance value of the transformer sections, including the TR section with the TM body and the TM section with the body.

What tool is used for the insulation resistance testing?

The tool used for insulation resistance testing is an insulation tester, referred to as 'majer' in the script.

What voltage is injected during the insulation resistance testing?

During the insulation resistance testing, a voltage of 5000 volts DC is injected, as the highest voltage the tester can handle is 5000 volts.

What is the significance of the polarization index in this test?

The polarization index is a key indicator of the insulation resistance quality. A value between 1.25 and 2.0 indicates that the insulation is in good condition.

What is the required testing time for each insulation resistance measurement?

Each insulation resistance measurement requires a testing time of 10 minutes.

How is the insulation resistance measured between the low voltage (TR) and body sections?

To measure the insulation resistance between the TR (low voltage) section and the body, the red probe is connected to the TR section's phase, and the black probe is connected to the body section.

What was the first resistance value measured for the TR section, and how was it assessed?

The first resistance value measured for the TR section was 37.9 gig ohms at the first minute, and it increased to 63.2 gig ohms by the 10th minute, giving a polarization index of 1.66, which is still considered good.

How is the insulation resistance measured between the medium voltage (TM) and body sections?

To measure the insulation resistance between the TM (medium voltage) section and the body, the red probe is moved to the medium voltage section, while the black probe is placed on the body section.

What was the polarization index value obtained for the TM section?

For the TM section, the polarization index value obtained was 1.59, which is still within the good category, as the value is between 1.25 and 2.0.

What does the resistance measurement between the TM and TR sections indicate?

The resistance measurement between the TM and TR sections showed a first-minute resistance value of 68.5 gig ohms and a 10th-minute resistance value of 119 gig ohms, resulting in a polarization index of 1.73, indicating that the insulation is in good condition.