This article is about To guide the responsible persons in conducting 13.8kV Switchgear Earthing Switch Tests.
SAFETY PRECAUTIONS – The following Safety precautions shall be taken in consideration prior, during and after conducting the test measurements.
- Safety tagging shall be implemented.
- Isolate the Area by Safety Warning Tape.
- Keep a Safe Distance from the device being tested.
- Wear Appropriate Personal Protective Equipment(PPE) Prior to starting any testing activity.
- Implementation of Proper Grounding.
13.8kV Switchgear Earthing Switch Test Procedure
TEST EQUIPMENTS: Megger IR test Kit, Contact Resistance Test Kit, Circuit Breaker Analyzer
- Perform the Insulation Resistance test.
1.1 Inject 5kV DC for 1 minute at Phase R with Phase Y + B connected to earth as per the following Test connection diagram and remove earthing wire from the earthing switch.
1.2 Repeat Above steps for Phase Y and B
1.3 Record the measured values in the applicable test forms and evaluate as per acceptable standards/criteria (>100 MΩ )
- Perform the Contact Resistance test.
2.1 Inject 100A for 1 minute at Phase R as per the following Test connection diagram:
2.2 Repeat Above for Phase Y and B
2.3 Record the measured values in the applicable test forms and evaluate as per acceptable standards/criteria (>1 GΩ).
- Perform the OPEN and CLOSE Timing test as per the following Test connection diagram.
3.1 Print and Record the measured values in the applicable test forms and evaluate as per acceptable standards/criteria (< 20 msec).
Why we need to perform 13.8kV Switchgear Earthing Switch Test?
The earthing switch in a 13.8kV switchgear system plays a critical role in ensuring the safety of personnel and equipment during maintenance and fault conditions. The earthing switch is designed to provide a controlled path for fault currents to ground, reducing the risk of electrical hazards. Conducting tests on the earthing switch is an essential part of the overall maintenance and safety procedures associated with medium voltage switchgear.
One crucial test performed on the earthing switch is the continuity test. This test verifies that the earthing switch can effectively establish a low-resistance path to ground when activated. A low-resistance connection is essential to safely discharge fault currents and to prevent the unintended energization of equipment during maintenance activities.
During the continuity test, the switchgear is typically disconnected from the power source, and the earthing switch is manually or electrically engaged. Test instruments are used to measure the resistance of the earthing switch to ensure it meets the specified requirements. Any deviation from the acceptable resistance values could indicate a potential issue with the earthing switch’s ability to provide a reliable fault path.
Additionally, insulation resistance tests are conducted to assess the integrity of insulation materials used in the earthing switch. This test helps identify any degradation or contamination of insulation that could compromise the switch’s performance. Ensuring proper insulation is crucial for maintaining the dielectric strength of the switchgear and preventing unintended current leakage.
Visual inspections are also a vital aspect of the earthing switch test. Inspectors check for physical damage, corrosion, or any signs of overheating. Damaged or corroded components can hinder the proper operation of the earthing switch and may pose safety risks.
The 13.8kV switchgear earthing switch test is not only about compliance with safety standards but also about maintaining the reliability and functionality of the switchgear system. A well-performing earthing switch contributes to the overall reliability of the power distribution network by providing an effective means of managing fault currents and ensuring the safety of personnel working on or around the switchgear.
Regular testing and maintenance of the earthing switch are essential components of the overall switchgear maintenance strategy. These activities help identify and address potential issues proactively, minimizing downtime, ensuring safety, and extending the operational life of the 13.8kV switchgear system.