Technical Parameters
- Part Number: 04215621XC0X4H1XXXXXX
- Manufacturer: Schweitzer Engineering Laboratories (SEL)
- Protection Type: Distance (Mho/Quad) and Directional Overcurrent
- Control Interface: Standard SEL-421 Front Panel with LCD
- Communication Ports: Ethernet (10/100 Mbps), EIA-232, EIA-485
- Protocol Support: SEL ASCII, Mirrored Bits, IEC 61850, DNP3, Modbus
- Rated Voltage/Frequency: 50/60 Hz nominal
- Operating Voltage: 125/250 Vdc or 120/240 Vac (Typical H-Power option)
Product Description
The SEL-421 is a high-speed protection, automation, and control system specifically designed for transmission line protection. It combines subcycle distance and directional elements with comprehensive automation logic. The 04215621XC0X4H1XXXXXX configuration provides a robust platform for high-speed tripping and reclosing, integrated synchrophasor measurement (IEEE C37.118), and advanced bay control. Its programmable SELogic control equations allow for complex interlocking and automation without the need for additional outboard hardware.
Application Areas
- Transmission Line Protection: High-speed distance protection for long and short transmission lines.
- Series-Compensated Lines: Advanced algorithms to handle voltage and current inversions.
- Bay Control: Complete control of one or two circuit breakers, including automated reclosing and synchronism check.
- Wide-Area Monitoring: Real-time synchrophasor reporting for power system stability analysis and load flow management.
Product Specifications
- Weight: 6.5 kg (Approx. 14.3 lbs)
- Dimensions: 482.6 mm x 177 mm x 248.4 mm (Standard 19-inch 4U Rack Mount)
- Country of Origin: United States (USA)
- Operating Temperature: -40°C to +85°C
Operating Precautions
- Current Transformer (CT) Integrity: Never open-circuit a CT secondary circuit while the primary is energized, as dangerously high voltages will occur.
- Isolation During Testing: Use test switches (such as SEL-FTU) to isolate the relay from the primary circuit before performing secondary injection testing.
- Firmware Verification: Verify that the “X” in the part number corresponds to the correct hardware revision for your specific ACSELERATOR QuickSet software version.
- Grounding: Ensure the chassis ground terminal is connected to the substation ground bus using a low-impedance conductor to minimize EMI interference.
Recommended Similar Products
| Model Number | Product Description | Primary Function |
|---|---|---|
| SEL-311C | Transmission Protection Relay | Distance/Reclosing |
| SEL-411L | Advanced Line Differential | Differential/Distance |
| SEL-421-5 | High-Speed Line Relay (5-inch) | Protection/Automation |
| SEL-451 | Protection & Bay Control | Feeder/Automation |
| SEL-351 | Directional Overcurrent Relay | Feeder Protection |
