AL-E290A – 3-PHASE PERCENTAGE BIASED DIFFERENTIAL PROTECTION RELAY TRAINER

Description

AL-E290A 3PHASE PERCENTAGE BIASED DIFFERENTIAL PROTECTION RELAY TRAINER

 AL-E290A – 3-PHASE PERCENTAGE BIASED DIFFERENTIAL PROTECTION RELAY TRAINER

1. General Description

The AL-E290A 3-Phase Percentage Biased Differential Protection Relay Trainer is a comprehensive laboratory training system designed for the practical study of three-phase transformer differential protection using the Merz-Price circulating-current principle.

The trainer enables students to understand percentage-biased differential relay operation, current-transformer connections, relay pickup characteristics, internal and external fault discrimination, transformer protection, and numerical relay configuration through a PC interface.

The system is supplied as a modular laboratory trainer with protected power-supply sections, current transformers, numerical differential relay, digital measurement instruments, fault/trip indication and suitable safety terminals.

2. Scope of Experiments

The trainer shall facilitate the following experiments:

1.Study of the operating principle of percentage-biased differential protection.

2.Study of Merz-Price differential protection of a three-phase transformer.

3.Plotting of the percentage-biased differential relay characteristics.

4.Determination of the relay pickup current.

5.Determination of the operating current of the differential relay.

6.Study of percentage bias and its effect on relay operation.

7.Verification of different relay bias settings.

8.Testing at 15%, 30% and 45% bias settings.

9.Simulation and study of in-zone/internal transformer faults.

10.  Verification of relay operation and tripping for internal faults.

11.  Simulation and study of out-of-zone/external faults.

12.  Verification of non-tripping for external faults.

13.  Study of circulating current under normal operating conditions.

14.  Study of differential current under fault conditions.

15.  Study of current-transformer operation in differential protection.

16.  Measurement of phase currents using digital ammeters.

17.  Study of relay trip indication.

18.  Study of numerical relay parameters and settings.

19.  PC communication with the numerical differential relay.

20.  Relay parameter setting through supplied software.

3. SYSTEM CONFIGURATION

The complete training system shall comprise:

4. THREE-PHASE POWER SUPPLY MODULE

The trainer shall incorporate an integrated three-phase power-supply section.

Specifications

·  Input voltage: 415 V AC

·  Number of phases: 3

·  Frequency: 50 Hz

·  Supply tolerance: ±10%

·  Phase identification: R-Y-B

·  MCB protection provided.

·  Emergency Stop facility provided.

·  Individual phase indication provided.

·  Clearly labelled input and output terminals.

·  Suitable protection against short circuit and abnormal operating conditions.

Protection

·  Three/four-pole MCB as appropriate to the system configuration.

·  Emergency isolation through emergency-stop switch.

·  Proper earthing provision.

·  Protected front-panel connection points.

5. THREE-PHASE CURRENT SOURCE MODULE

A dedicated current-source section shall be provided for testing the differential protection relay.

Specifications

·  Current-source arrangement: 3 Nos.

·  Source specification: 440 V / 24 V / 20 A

·  Three-phase operation.

·  Controlled current injection facility.

·  Suitable for differential relay characteristic testing.

·  Suitable for pickup-current testing.

·  Suitable for internal and external fault simulation.

·  Output available through safety terminals.

·  Current adjustment/control shall be provided as required for laboratory testing.

The current source shall permit controlled variation of test current for obtaining relay operating and restraining characteristics.

6. CURRENT TRANSFORMER MODULE

The trainer shall include three current transformers for three-phase differential protection experiments.

Specifications

·  Number of CTs: 3 Nos.

·  Application: Differential protection

·  Three-phase measurement.

·  Suitable secondary connection for numerical differential relay.

·  Secondary terminals brought to front panel.

·  Safety sockets provided.

·  Clearly marked CT polarity and terminals.

·  Designed to demonstrate circulating-current operation.

The CT arrangement shall permit students to investigate the relationship between primary current, secondary current, differential current and restraining current.

7. NUMERICAL DIFFERENTIAL PROTECTION RELAY

The main protection element shall be a numerical high-speed percentage-biased differential protection relay.

Electrical Specifications

·  Relay type: Numerical percentage-biased differential relay

·  Application: Three-phase transformer differential protection

·  Operating principle: Biased differential protection

·  Relay current rating: 1 A

·  Bias settings:

o   15%

o   30%

o   45%

·  Bias selection: Plug-board/tap arrangement

·  Auxiliary supply: 110 V DC

·  High-speed operation.

·  Differential protection function.

·  Trip output.

·  Fault/event indication.

Relay Functions

The relay shall provide facilities for:

·  Differential-current measurement.

·  Restraining/bias-current measurement.

·  Pickup-current determination.

·  Percentage-biased operation.

·  Trip indication.

·  Fault indication.

·  Relay setting adjustment.

·  Communication with a PC.

8. RELAY COMMUNICATION AND SOFTWARE

A PC communication interface shall be provided for configuration and monitoring of the numerical relay.

Specifications

·  Communication port: RS-232

·  PC interface: RS-232 to USB converter

·  Relay configuration software: Supplied

·  Software supplied on CD/media.

·  PC-based relay setting facility.

·  Parameter configuration facility.

·  Relay status monitoring.

·  Suitable for educational demonstration of numerical relay configuration.

9. DIGITAL METER MODULE

The trainer shall incorporate a digital measurement section.

Digital AC Ammeter

·  Number of digital AC ammeters: 6 Nos.

·  Measurement type: AC current.

·  Digital display.

·  Suitable for monitoring the relevant phase/relay currents.

·  Individual measurement points shall be clearly identified.

Digital Timer

·  Number: 1 No.

·  Digital time measurement.

·  Suitable for demonstrating relay/trip operating time where applicable.

·  Clear digital indication.

10. TRIPPING INDICATION MODULE

A dedicated trip indication section shall be provided.

Specifications

·  Lamp holders: 230 V, 2 Nos.

·  Indication lamps provided.

·  Control switch provided.

·  Visual indication of relay operation.

·  Provision for observing trip/non-trip conditions.

·  Buzzer indication associated with relay operation.

11. DIFFERENTIAL PROTECTION TEST CIRCUIT

The front panel shall incorporate a clearly identified circuit for demonstrating differential protection.

The circuit shall provide:

·  CT connections.

·  Transformer connection points.

·  Relay input connections.

·  Current injection points.

·  Differential-current measurement points.

·  Trip output connections.

·  Fault simulation points.

·  Test points for external and internal fault conditions.

·  Clearly labelled R-Y-B phase circuits.

The arrangement shall permit students to construct and verify the protection circuit without requiring external wiring beyond the supplied patch cords and associated transformer/load units.

12. IN-ZONE FAULT STUDY

The trainer shall provide facilities to demonstrate an internal/in-zone transformer fault.

During an in-zone fault:

·  CT secondary currents become unequal according to the simulated fault condition.

·  A differential current is produced.

·  The numerical differential relay detects the differential condition.

·  Relay operation/tripping is indicated.

·  Trip indication lamp/buzzer operates as applicable.

Students shall be able to observe the relationship between fault current, differential current and relay operation.

13. OUT-OF-ZONE FAULT STUDY

The system shall also facilitate demonstration of external/out-of-zone fault conditions.

During an external fault:

·  Corresponding CT currents circulate through the differential circuit.

·  The relay should remain restrained under properly balanced external-fault conditions.

·  The non-tripping condition can be verified.

·  Students can compare external-fault behaviour with internal-fault behaviour.

14. PERCENTAGE-BIAS CHARACTERISTIC TEST

The trainer shall permit the user to obtain the relay operating characteristic.

Available bias settings

·  15%

·  30%

·  45%

Students shall be able to vary the test currents and record:

·  Operating current.

·  Restraining current.

·  Pickup point.

·  Trip/non-trip condition.

·  Bias percentage.

The recorded values can subsequently be used to plot the relay characteristic curve.

15. PICKUP TEST

The system shall provide facilities for determining the relay pickup current.

Procedure capability

The user shall be able to:

1.Apply the appropriate test current.

2.Gradually increase the current.

3.Observe relay status.

4.Record the current at which the relay operates.

5.Repeat the test for different bias settings.

6.Compare the measured results.

16. SAFETY FEATURES

The trainer shall incorporate appropriate electrical safety provisions.

Safety provisions

·  MCB-based short-circuit protection.

·  Emergency Stop switch.

·  Proper earthing provision.

·  4 mm safety sockets.

·  Insulated front-panel construction.

·  Clearly identified terminals.

·  Protected high-voltage connection points.

·  Properly insulated internal wiring.

·  Phase identification.

·  Warning/safety labels where required.

·  Protected current-source outputs.

Note: High-voltage circuits shall be operated only under appropriate laboratory supervision and according to the manufacturer's operating manual.

17. PATCH CORDS

Heavy-duty patch cords shall be supplied for laboratory connections.

Specifications

·  Connector size: 4 mm

·  Type: Heavy-duty safety patch cord.

·  Approximate length: 1 metre

·  Quantity: Suitable complete set.

·  Insulated connectors.

·  Suitable for repeated laboratory use.

18. FRONT PANEL

The front panel shall be professionally designed for educational use.

It shall include:

·  Clearly printed circuit diagrams.

·  Functional block identification.

·  Input/output terminal markings.

·  R-Y-B phase identification.

·  Meter identification.

·  CT terminal identification.

·  Relay terminal identification.

·  Bias-setting identification.

·  Trip indication.

·  Emergency Stop.

·  MCB.

·  Control switches.

·  Safety warnings.

·  Experiment-related symbols and labels.

19. MECHANICAL CONSTRUCTION

Construction

·  Modular laboratory trainer.

·  Rack-type construction.

·  Aluminium extruded metal profile/cabinet.

·  Robust and suitable for institutional laboratory use.

·  Front-accessible modules.

·  Components securely mounted.

·  Provision for convenient handling and installation.

Approximate Dimensions

42" × 24"

Dimensions may be suitably modified depending on final module configuration.

20. AL-E295 – THREE-PHASE TRANSFORMER UNIT

The differential protection trainer shall be used with a compatible three-phase transformer unit.

Specifications

·  Model: AL-E295

·  Type: Three-phase transformer.

·  Nominal rating: 1 kVA per phase

·  Primary voltage: 440 V

·  Secondary voltage: approximately 220 V

·  Transformer ratio: approximately 2:1 step-down

·  Supply frequency: 50 Hz

·  Three-phase operation.

·  Copper windings.

·  High insulation.

·  Tap positions: 0%, 0%, 86.6% and 100%

·  High-voltage test points.

·  4 mm safety sockets / BTI-15 terminals.

·  Fuse-based short-circuit protection.

·  Metal cabinet construction.

Approximate Dimensions

18" × 12"

21. AL-E277A – THREE-PHASE RESISTIVE LAMP LOAD

General Specifications

·  Model: AL-E277A

·  Type: Three-phase resistive lamp load.

·  Capacity: 3 kW

·  Operating voltage: 415 V AC

·  Frequency: 50 Hz

·  Number of control switches: 30

·  Approximate current per switch: 400 mA

·  Number of lamps: 30 Nos.

·  Three-phase operation.

·  Phase indication provided.

·  Current meter: Optional.

Construction

·  Insulated Bakelite front panel.

·  Printed circuit diagrams and symbols.

·  25 mm multi-colour phase indicators.

·  4 mm heavy-duty patch cords.

·  4 mm safety sockets.

·  4-pole MCB protection.

·  Metal cabinet.

·  Wheels for mobility.

Approximate Dimensions

18" × 24"

22. COMPLETE SYSTEM PACKING LIST

23. DOCUMENTATION SUPPLIED

The following documentation shall be supplied with the system:

·  Detailed operating manual.

·  Experiment manual.

·  Circuit diagrams.

·  Connection diagrams.

·  Technical specifications.

·  Relay operating instructions.

·  PC software installation instructions.

·  Relay-setting instructions.

·  Safety instructions.

·  Troubleshooting guidelines.

24. KEY SPECIFICATIONS AT A GLANCE

System Description

AL-E290A is therefore a complete educational platform for studying three-phase percentage-biased differential protection, combining a numerical relay, three-phase CT arrangement, transformer unit, controlled current source, digital measurement, fault/trip indication and PC-based relay configuration. The system is suitable for practical demonstrations, laboratory experiments, relay characteristic testing and transformer protection studies.

Technical Details