Protective Relay Coordination

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This tool provides a conceptual framework for protective relay coordination. You can input system parameters, configure overcurrent relays, and visualize their time-current characteristics (TCC) for coordination assessment. **Note: This is a simplified model for demonstration; full engineering analysis requires specialized software.**

1. System Configuration

System Voltage (kV)

Source Short Circuit MVA (at PCC)

Line Impedance (Ohms/phase)

Normal Load Current (A)

Coordination Time Interval (CTI) (s)

2. Relay Data

Overcurrent (50/51)

Differential (87)

Distance (21)

Configure two series overcurrent relays (downstream and upstream) for coordination.

Downstream Relay (e.g., Feeder Breaker)

CT Ratio (Primary/Secondary)

Characteristic Curve

Pick-up Current (A) (Primary)

Time Multiplier Setting (TMS)

Upstream Relay (e.g., Substation Main)

CT Ratio (Primary/Secondary)

Characteristic Curve

Pick-up Current (A) (Primary)

Time Multiplier Setting (TMS)

Differential relays are used for fast and sensitive protection of equipment like transformers, generators, and busbars. Configure parameters for two CTs on either side of the protected equipment (e.g., a transformer).

CT 1 (e.g., Primary Side)

CT Ratio (Primary/Secondary)

Primary Current (A)

CT 2 (e.g., Secondary Side)

CT Ratio (Primary/Secondary)

Primary Current (A)

Differential Relay Settings

Differential Pick-up (A) (Secondary)

Bias Slope 1 (%)

Bias Slope 2 (%)

Slope Change Point (A) (Secondary)

Instantaneous Pick-up (A) (Secondary)

Distance relays provide primary and backup protection for transmission lines based on impedance. They have multiple zones with time delays. Input parameters for a single distance relay protecting a line section.

Distance Relay Settings

System Voltage (kV)

VT Ratio (Primary/Secondary)

CT Ratio (Primary/Secondary)

Protected Line Impedance (Ohms Primary)

Zone 1 Reach (% of Line Impedance)

Zone 2 Reach (% of Line Impedance)

Zone 2 Time Delay (s)

Zone 3 Reach (% of Line Impedance)

Zone 3 Time Delay (s)

Simulated Fault Impedance (Ohms Primary)

Coordination Analysis Summary

Parameter	Value

Time-Current Characteristic (TCC) Plot

**Note:** This plot is a simplified illustration. Actual TCC curves require precise logarithmic scaling and plotting based on specific relay models and standards. For detailed analysis, specialized software is recommended.

Protective relay coordination adheres to principles and standards set by organizations such as:
- IEEE (Institute of Electrical and Electronics Engineers): E.g., IEEE Std 242 (Buff Book) for Industrial and Commercial Power Systems Protection, and various guides for specific relay types.
- IEC (International Electrotechnical Commission): E.g., IEC 60255 series for Measuring Relays and Protection Equipment.
- ANSI (American National Standards Institute): Relevant standards for device numbers and relay functions.