Product Name

• “SR489”: Identifies the “System Relay (SR)” 489 series, specialized in generator management.
• “P5”: Specifies 5A phase current transformer (CT) secondary input (critical for current-based protection).
• “LO”: Indicates low-voltage control power (20–60 VDC / 20–48 VAC), suitable for industrial low-voltage systems.
• “A20”: Denotes 4–20 mA analog output (for transmitting measured data like current/voltage to SCADA/DCS).
• “E”: Signifies enhanced 40-character LCD display (for real-time parameter monitoring and diagnostics).

  This relay acts as a “generator guardian,” combining protection (e.g., overcurrent, undervoltage), measurement, and communication to ensure safe, efficient generator operation.)

2. Product Description

• Power Generation Plants: Protecting diesel/gasoline generators from overloads and short circuits while optimizing energy output.
• Marine Applications: Managing onboard generators for propulsion and auxiliary systems, with robust performance in harsh maritime environments.
• Oil & Gas Industry: Safeguarding remote drilling rig generators, where downtime risks production losses and safety hazards.
• Industrial Facilities: Controlling backup generators to ensure uninterrupted power for critical equipment (e.g., data centers, manufacturing lines) 。

Key Functional Advantages

1. Comprehensive ANSI-Standard ProtectionIntegrates over 10 protection functions compliant with ANSI/IEEE standards to shield generators from faults:
   • Overcurrent Protection (ANSI 51): Adjustable time-delay curves (inverse, definite) to trip circuits during overloads.
   • Over/Undervoltage Protection (ANSI 59/27): Triggers alarms/trips if voltage deviates ±10% from nominal (0–25,000 V range) .
   • Ground Fault Protection (ANSI 50N): Detects leakage current to prevent insulation damage and fire risks.
   • Phase Reversal Protection: Blocks generator operation if phase sequence is incorrect, avoiding motor damage .
2. High-Precision Electrical MeasurementFeatures 12-sample-per-cycle data acquisition for accurate monitoring of key parameters:
   • Voltage/Current: Measures phase voltage (up to 25,000 V) and current (via 5A CT input) with ±0.2% accuracy.
   • Power Metrics: Tracks active power (kW), reactive power (-2.00 to +2.00× rated voltage MVAR), and power factor (0.01–1.00 lead/lag) .
   • Frequency: Monitors 25/50/60 Hz systems with a 0.00–90.00 Hz range, critical for grid synchronization .
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3. Flexible Communication & Data TransmissionSupports dual RS485 ports with Modbus RTU/DNP 3.0 protocols (up to 19200 bps) for seamless integration with SCADA/DCS systems . The 4–20 mA analog output transmits real-time data (e.g., generator current) to remote monitors, eliminating the need for external converters. A USB port and CompactFlash™ slot enable on-site configuration and data logging .
4. User-Friendly Operation & DiagnosticsEquipped with a 40-character LCD display, status LEDs, and a numeric keypad for intuitive parameter adjustment and fault viewing . Built-in self-diagnostics detect wiring faults (e.g., open CTs) and component failures, sending alerts via the display or communication ports—cutting troubleshooting time by 60% compared to basic relays.
5. Rugged Design for Harsh EnvironmentsConstructed with a harsh-environment coating (optional) and compliant with EMC standards (IEEE/ANSI C37.90.1) to resist interference from motors and high-voltage equipment . It operates reliably in -40°C to +70°C temperatures and 5%–95% non-condensing humidity, making it suitable for offshore and desert applications.

3. Product Parameters

3.1 Core Protection & Measurement Parameters