Pre-Commissioning Procedures and Formats for Substation Equipment & Protection System
Pre-Commissioning Procedures and Formats for Substation Equipment & Protection System
1. Introduction
Pre-commissioning is the process of inspecting, testing, and verifying substation equipment and protection systems before they are put into operation. It ensures that all components are installed correctly, free of defects, and functioning as per design specifications. This step is critical for reliability, safety, and performance.
2. Pre-Commissioning Procedures
The pre-commissioning process consists of various inspections and testing activities for substation equipment and the protection system.
A. General Inspection
Before conducting electrical tests, a general inspection is performed to check:
- Physical Installation – Ensuring all equipment such as transformers, circuit breakers (CBs), current transformers (CTs), potential transformers (PTs), relays, and control panels are installed as per the design layout.
- Earthing & Bonding – Verifying that earthing is properly connected and meets safety standards.
- Cable Dressing & Labeling – Checking that all cables are properly routed, secured, and labeled for easy identification.
- Mechanical Integrity – Inspecting for any physical damage, loose connections, or missing components.
B. Power Equipment Testing
This phase involves conducting electrical tests on major power equipment.
1. Power Transformers
Transformers are tested to confirm their electrical and mechanical integrity:
- Insulation Resistance (IR) Test – Measures insulation quality of windings.
- Transformer Turns Ratio (TTR) Test – Ensures the correct voltage transformation ratio.
- Oil Dielectric Strength Test – Checks the insulating properties of transformer oil.
- Winding Resistance Test – Identifies any issues with winding continuity.
- Magnetizing Current Test – Detects core issues or shorted turns.
- Vector Group Test – Verifies correct phase connections.
2. Circuit Breakers (CBs)
Circuit breakers are tested to ensure they operate reliably under fault conditions:
- Contact Resistance Test – Measures resistance across breaker contacts.
- Timing Test (Opening & Closing Time) – Ensures correct response time during operation.
- Insulation Resistance Test – Checks insulation between terminals and ground.
- SF6 Gas Leakage & Dew Point Test (for SF6 CBs) – Confirms gas quality and leakage levels.
3. Current Transformers (CTs) & Potential Transformers (PTs)
Instrument transformers are tested to verify their accuracy and insulation:
- Polarity and Ratio Test – Ensures correct polarity and transformation ratio.
- Magnetization Curve Test – Evaluates core saturation characteristics.
- Insulation Resistance Test – Confirms insulation integrity.
4. Busbars & Cables
Busbars and power cables are tested to ensure electrical safety and performance:
- High Voltage (HV) Test – Checks withstand capacity under high voltage.
- Continuity & Insulation Test – Confirms proper conductor continuity and insulation quality.
C. Protection System Testing
Protection relays and communication systems must be tested to confirm reliability.
1. Relay Testing
Protective relays are tested to verify their response to electrical faults:
- Functional Testing – Checks operation of overcurrent, differential, and distance relays.
- Secondary Injection Test – Simulates electrical conditions to verify relay settings.
- Trip Circuit Supervision Test – Ensures the breaker trip circuit is healthy.
2. SCADA & Communication Systems
Substations with SCADA (Supervisory Control and Data Acquisition) require communication system testing:
- Signal Checking & Loop Testing – Verifies control and status signals between remote and local systems.
- Communication Protocol Verification – Ensures compliance with required communication standards.
- Remote Operation & Status Monitoring – Tests remote control and monitoring functions.
3. Pre-Commissioning Formats
All test results must be recorded in standard formats to ensure a structured approach, traceability, and compliance with industry standards (IEC, IEEE, etc.). The following are common test formats:
- General Inspection Checklist – Documents physical and mechanical checks.
- Transformer Pre-Commissioning Test Report – Records test results for transformers.
- Circuit Breaker Testing Format – Logs breaker test data and performance results.
- CT & PT Test Report Format – Documents instrument transformer test results.
- Relay Test Report – Captures protection relay settings and functional test outcomes.
- SCADA System Test Report – Details communication system verification and performance.
- Earthing System Test Report – Records earth resistance and grounding system compliance.
Conclusion
Pre-commissioning is a crucial step in ensuring that substation equipment and protection systems function correctly and reliably. Proper testing and documentation help prevent failures, improve safety, and ensure compliance with regulatory standards.
Pre-Commissioning Procedures and Formats for Substation Equipment & Protection System