The Emerson A6120 (part of the Emerson / CSI AMS 6500 Machinery Health Monitor series) is a dual-channel shaft vibration monitoring module. Installed in an AMS 6500 19-inch rack chassis, the A6120 continuously measures relative shaft vibration (eddy-current probe inputs) on critical rotating machinery such as steam/gas turbines, large pumps, compressors, and electric motors to provide real-time machinery protection and API 670 compliant monitoring.
Key Specifications & Identification
| Attribute | Details |
| Manufacturer | Emerson Automation Solutions (CSI / AMS) |
| Part / Model Code | A6120 |
| System Platform | Emerson AMS 6500 Machinery Health Monitor / EPRO System |
| Number of Channels | 2 Independent Sensor Channels (Shaft Vibration / Relative Displacement) |
| Sensor Compatibility | Eddy Current Probes / Proximity Transducers (e.g., PR6422, PR6423, PR6424, CON0x1) |
| Standard Compliance | Designed to satisfy API 670 machinery protection requirements |
| Outputs | Dual buffered raw sensor outputs (BNC/terminals), 4–20 mA current outputs, relay outputs |
| Status Indicators | Front-panel status LEDs for Channel OK, Alert, and Danger/Trip limits |
Primary System Functions
- Relative Shaft Vibration Measurement: Converts high-frequency signals from non-contacting eddy current displacement sensors into overall shaft vibration measurements (peak-to-peak amplitude in \mum or mils).
- API 670 Safety Trip Interlocks: Features configurable Alert and Danger alarm thresholds with internal relay logic to trigger emergency shutdown sequence (ESD) or machinery protection trips during destructive vibration events.
- Buffered Transducer Signals: Provides front-panel or rear buffered raw analog outputs for direct connection to portable machinery diagnostic tools (such as the AMS 2140 or spectrum analyzers) without disturbing active protection loops.
- 4–20 mA DCS / PLC Interfacing: Outputs proportional 4–20 mA DC current signals for each channel, transmitting vibration trends directly to plant Distributed Control Systems (Emerson DeltaV, Ovation, etc.).
Servicing & Replacement Guidelines
- Sensor Power Isolation: Verify eddy current sensor driver (eddy-current transmitter/converter) power levels (-24 V DC nominal) prior to landing signal wires to prevent damage to input amplifier circuits.
- ESD & Static Precautions: CMOS processing circuits are sensitive to static electricity. Always wear a grounded anti-static wrist strap when inserting or removing the A6120 module from the AMS 6500 rack backplane.
- Hardware & Software Configuration: When replacing an A6120 module, verify DIP switch settings on the card edge and reload channel parameters (sensor sensitivity, frequency filter bands, trip delays) using AMS Equipment Performance Monitor / AMS Machinery Manager configuration tools.
- Hot-Swap & Safety Precautions: While AMS 6500 modules support rack insertion, bypass machine trip relays before removing or replacing an active A6120 card to avoid false machine trip signals during handling.
