EMERSON A6370D – Programmable Controller / Overspeed Protection Monitor

Technical Specifications

• Electrical Parameters:
  • Input Voltage: 24 VDC ±15% (short-circuit proof, galvanically isolated) .
  • Sensor Compatibility:
    • Eddy Current/Hall Element Sensors: Voltage range ±48 V, frequency 0–20 kHz, input resistance 100 kΩ .
    • Magnetic (VR) Sensors: Voltage 1–30 V RMS, frequency 0–20 kHz, input resistance 18 kΩ .
  • Outputs:
    • Digital Inputs: 4 galvanically isolated channels (logic high: 13–31 V, logic low: 0–5 V) .
    • Current Outputs: 2 isolated channels (0/4–20 mA, accuracy ±1% of full scale) .
    • Digital Outputs: 7 short-circuit-proof channels (max current 25 mA) .
    • Pulse Outputs: 3 open-collector channels (max voltage 31.2 V, frequency 0–20 kHz) .
• Performance:
  • Speed Range: 0–100,000 RPM with ±0.05% full-scale accuracy .
  • Response Time: <12.5 ms in automatic mode for overspeed detection .
  • Communication: RS-485 (Modbus RTU) and optional Profibus DP (A6370D/DP variant) .
• Physical & Environmental:
  • Dimensions: 211 mm × 130 mm × 43 mm (8.31″ × 5.12″ × 1.70″) in 3 RU/42 HP rack mount .
  • Weight: 0.49 kg (1.08 lb) .
  • Operating Temperature: -20°C to +65°C (-4°F to 149°F), 5–95% non-condensing humidity .
  • Shock/Vibration Resistance: Compliant with IEC 60068-2-6 (20 m/s²) and IEC 60068-2-27 (100 m/s²) .
  • Certifications: SIL 3 (TÜV-certified), IEC 61508:2010, IP20 (rack-mounted) .

Functional Features

1. Safety-Critical Design:
   • Triple-Modular Redundancy (TMR): In the AMS 6300 SIS, three A6370D monitors and one A6371 backplane form a TMR system, ensuring fault tolerance and diagnostic coverage >99% .
   • SIL 3 Compliance: Meets the highest safety integrity level for applications requiring fail-safe operation .
2. Multi-Sensor Fusion:
   • Supports eddy current, Hall effect, and magnetic sensors, enabling redundant speed measurement from different technologies .
   • Automatic sensor health monitoring with diagnostic alerts for signal loss or drift .
3. Programmable Logic:
   • Configurable speed setpoints (e.g., alarm, trip) for different operating conditions (e.g., startup, normal, emergency) .
   • Customizable logic for cascading shutdown sequences (e.g., triggering auxiliary systems before main shutdown) .
4. Real-Time Diagnostics:
   • LED Indicators: Front-panel lights for power status, sensor health, and trip activation .
   • Remote Monitoring: RS-485 interface provides access to live speed data, diagnostic logs, and configuration parameters .
5. Rugged Reliability:
   • Conformal coating protects against corrosive gases and dust (ISA-S71.04 Class G3) .
   • Hot-swap capability allows module replacement without system downtime .

Application Scenarios

1. Power Generation:
   • Steam/Gas Turbines: Monitors shaft speed in thermal/nuclear power plants, triggering emergency trips if speed exceeds 110% of rated value .
   • Wind Turbines: Prevents overspeed during grid disconnection or blade pitch system failures .
2. Oil & Gas:
   • Centrifugal Compressors: Ensures safe operation in offshore platforms and pipelines by detecting surge conditions caused by speed fluctuations .
   • Drilling Rigs: Protects mud pumps and top drives from overspeeding during high-pressure operations .
3. Chemical Processing:
   • Reactor Agitators: Maintains safe rotational limits for high-viscosity mixing equipment to avoid mechanical failure .
   • Extruders: Monitors screw speed in polymer production lines to prevent material degradation due to excessive friction .
4. Marine:
   • Propulsion Engines: Guards against overspeed in ship turbines during sudden load changes (e.g., propeller cavitation) .
   • Diesel Generators: Maintains frequency stability by regulating engine speed during power demand spikes .

Functional Architecture

• Hardware:
  • 32-Bit Processor: Executes real-time speed calculations and diagnostic algorithms with μs-level precision .
  • Isolation Circuits: Optocouplers and surge protectors shield against voltage transients up to 2.5 kV .
• Software:
  • Configuration Tool: EPRO’s Train Tools software for parameter setup, firmware updates, and fault analysis .
  • Data Logging: Stores up to 1,000 events with timestamps for root-cause analysis of overspeed incidents .

Typical System Integration

• Triple A6370D Monitors: Each connected to independent speed sensors (e.g., two eddy current, one magnetic) .
• A6371 Backplane: Provides power distribution, data synchronization, and voting logic for the TMR system .
• Human-Machine Interface (HMI): Displays real-time speed trends and alarm history via Modbus RTU integration .
• Actuation: Trip signals sent to solenoid valves or motor contactors to shut down machinery within 50 ms of detection .

Safety & Compliance

• Cybersecurity: Role-based access control (RBAC) prevents unauthorized changes to trip setpoints .
• Redundancy:
  • Dual Power Supplies: 24 VDC inputs from separate sources ensure uninterrupted operation .
  • Diagnostic Coverage: >99% self-test coverage for internal components (e.g., memory, processor) .
• Environmental Sustainability: RoHS-compliant lead-free design .