Advanced IDMT Relay Curve Testing Using MP3000A Relay Test System
Modern numerical protection relays require accurate and repeatable testing methods during commissioning, maintenance and factory acceptance testing (FAT). One of the most important verification procedures is IDMT relay curve testing based on IEC standards.
The MP3000A protective relay test system offers advanced automated testing for IEC IDMT curves with configurable tolerance methods, automatic pass/fail judgement, expected trip time calculation and actual measured trip time comparison.
This page demonstrates automated testing of the IEC Very Inverse (IEC VI) curve using different relative tolerance settings to show how advanced software-based verification can improve relay testing quality and analysis.
What is IEC VI curve testing?
IEC Very Inverse (VI) is one of the standard IDMT overcurrent relay characteristics used in power system protection. The relay operating time depends on the magnitude of fault current relative to the pickup setting.
IEC VI curves are widely used in:
- Feeder protection
- Distribution systems
- Transformer protection
- Industrial power systems
- Utility substations
- Backup overcurrent protection schemes
During testing, the relay test software calculates the expected operating time according to the selected IEC VI curve and compares it with the actual measured trip time from the relay.
The software then determines whether the relay performance is within the specified tolerance limits.
Automated IEC VI Curve Testing
The MP3000A relay test software includes a dedicated I-T curve verification module for automatic testing of IDMT relays.
Key Features
- IEC standard curve database
- IEC VI curve selection
- Automatic curve refresh according to relay settings
- Automatic test point generation
- Expected trip time calculation
- Actual measured trip time recording
- Relative tolerance setting
- Automatic pass/fail judgement
- Graphical curve analysis
- Comprehensive test reporting
This allows engineers to perform fast, repeatable and standardised relay testing during commissioning and maintenance activities.
Demonstration 1 – IEC VI Curve Test with 5% Relative Tolerance
In this demonstration video, the IEC VI curve is selected from the software database. The relay settings are updated, and the software automatically calculates the expected trip times at different test points.
The relative tolerance is configured to 5%.
The software compares the expected trip time and actual measured trip time for every test point and determines that the relay performance is within the acceptable tolerance band.
As a result, the test status is displayed as PASSED.
What This Demonstrates
- Practical field testing conditions
- Standard engineering acceptance criteria
- Automatic comparison between theoretical and measured values
- Fast relay verification during commissioning
- Reliable pass/fail analysis
Video – IEC VI Curve Test with 5% Relative Tolerance
IEC VI IDMT relay testing using 5% relative tolerance. The relay passes because the measured trip times remain within the configured acceptance band.
Demonstration 2 – IEC VI Curve Test with 0.01% Relative Tolerance
In this second demonstration, the same IEC VI curve is tested using an extremely strict relative tolerance setting of 0.01%.
The software again calculates the expected operating time and compares it against the actual relay operating time measured during the test.
Due to the extremely narrow tolerance band, the software detects deviation beyond the configured acceptance limit, and the test status is displayed as FAILED.
What This Demonstrates
This demonstration highlights the advanced analytical capability of the relay test software.
The objective is not merely to pass or fail a relay but to provide engineers with precise and configurable verification tools.
The software allows users to:
- Analyse relay timing accuracy in detail
- Study small timing deviations
- Configure custom engineering tolerance limits
- Perform advanced quality verification
- Support R&D, FAT and validation testing
- Compare expected and actual relay behaviour with high precision
Video – IEC VI Curve Test with 0.01% Relative Tolerance
IEC VI IDMT relay testing using extremely strict 0.01% relative tolerance. The software detects deviation outside the configured limit and reports test failure
Why Relative Tolerance Matters in Relay Testing
Different testing scenarios require different acceptance criteria.
For example:
| Application | Typical Requirement |
|---|---|
| Routine maintenance testing | Practical tolerance |
| Field commissioning | Standard acceptance tolerance |
| Factory acceptance testing | Controlled verification |
| Research and development | Extremely strict analysis |
| Comparative relay evaluation | High-precision testing |
The ability to configure relative tolerance settings gives protection engineers greater flexibility and analytical control during relay testing.
Benefits of Advanced Automated Relay Testing
Improved Testing Consistency
Automatic calculation and comparison reduce operator dependency and improve repeatability.
Faster Commissioning
Automatic test sequences significantly reduce manual testing time.
Better Documentation
The software automatically generates detailed test reports, including:
- Test points
- Expected trip times
- Actual measured times
- Deviation values
- Pass/fail status
Advanced Engineering Analysis
Configurable tolerance methods allow deeper understanding of relay behaviour and timing characteristics.
Suitable for Multiple Applications
The testing system can be used for:
- Numerical relays
- Electromechanical relays
- Static relays
- Utility substations
- Industrial plants
- Transmission systems
- Distribution networks
IEC VI Relay Testing Applications
The IEC VI testing module is useful for:
- Overcurrent relay testing
- Feeder relay commissioning
- Substation maintenance
- Protection relay calibration verification
- Relay timing verification
- Acceptance testing
- Periodic preventive maintenance
- Utility protection system testing
MP3000A Relay Test System – Import, Supply and Support in India
The MP3000A protective relay test system is imported, supplied and technically supported in India by Myriad Industrial Solutions LLP.
The system supports advanced protection relay testing functions, including:
- IDMT relay testing
- IEC and IEEE curves
- Distance relay testing
- Differential relay testing
- Synchronising relay testing
- Binary I/O testing
- Dynamic state testing
- Automatic test sequencing
- Report generation
The software-based automated testing approach helps engineers perform accurate, repeatable and efficient protection relay verification.
Contact Us for Advanced Relay Testing Solutions
For demonstrations, technical discussions or quotations related to protective relay test systems, please contact us.
Applications include:
- Power utilities
- Industries
- EPC companies
- Substation commissioning
- Electrical maintenance contractors
- Protection engineers
- Testing and commissioning agencies
We support advanced relay testing requirements across India.
