Description
The Emerson A6120 is a Case Seismic Vibration Monitor for the CSI 6500 Machinery Health Monitor platform. Emerson documentation identifies it as a two-channel, 3U, single-slot plug-in monitor designed for high-reliability monitoring of critical rotating machinery. It is intended for use with electrodynamic seismic transducers and can provide vibration monitoring, alarm functions, and relay-based machinery protection.
The A6120 is commonly used on steam turbines, gas turbines, compressors, hydro turbines, and other rotating equipment where casing vibration needs to be continuously monitored. Emerson specifies the module for API 670-type machinery protection applications.
Key Features
- Emerson CSI 6500 Machinery Health Monitor
- A6120 Case Seismic Vibration Monitor
- 2 independent vibration channels
- 3U, 1-slot plug-in design
- Compatible with Emerson electrodynamic vibration sensors
- Alarm and trip monitoring
- Front and rear buffered/proportional outputs
- 0/4–20 mA and 0–10 V output capability
- Hot-swappable design
- Remote limit-multiply and trip-bypass functions
- Password-protected configuration
Product Datasheet
| Parameter | Specification |
|---|---|
| Brand | Emerson |
| Model | A6120 |
| Product Type | Case Seismic Electro-dynamic Vibration Monitor |
| System | CSI 6500 Machinery Health Monitor |
| Channels | 2 independent channels |
| Sensor Type | Electrodynamic / electromechanical |
| Compatible Sensors | Emerson 9266 / 9267 / 9268 |
| Input Type | Differential |
| Input Isolation | Galvanically isolated from power supply |
| Input Resistance | >100 kΩ |
| Input Voltage Range | -5 to +15 VDC |
| Lower Frequency Cutoff | 1 or 5 Hz |
| Upper Frequency Cutoff | 50–2000 Hz adjustable |
| Measuring Range | 5–100 mm/s RMS |
| Frequency Range | 10–1000 Hz typical |
| Current Output | 0/4–20 mA |
| Voltage Output | 0–10 V |
| Power Consumption | Max. 6 W |
| Supply Current | Up to 250 mA at 24 VDC |
| Mounting | 3U, 1-slot rack module |
| Configuration | Password protected |
| Application | Machinery vibration monitoring/protection |
The core specifications above are based on Emerson’s A6120 documentation and specification sheet.
Functional Description
The A6120 receives signals from electrodynamic casing-seismic vibration sensors and continuously evaluates the vibration condition of rotating machinery. Its two channels operate independently, allowing two vibration measurements to be monitored from a single rack slot.
The module can compare measured vibration against configured alarm limits and provide protection-related outputs. This makes it part of a larger machinery protection architecture rather than a conventional PLC I/O board. Emerson specifically describes it for critical rotating equipment and API 670 machinery protection applications.
Typical Applications
- Steam turbines
- Gas turbines
- Hydro turbines
- Centrifugal compressors
- Rotating machinery
- Power-generation plants
- Oil & gas facilities
- Machinery protection systems
- CSI 6500 machinery monitoring cabinets
Installation & Configuration
- Verify the module marking A6120.
- Confirm compatibility with the CSI 6500 rack.
- Identify the installed vibration transducers.
- Check sensor wiring and polarity.
- Install the module in the designated rack slot.
- Connect the field sensor interfaces.
- Verify the 24 VDC system supply.
- Configure measurement range and frequency filtering.
- Set alarm and trip limits according to the approved machinery-protection specification.
- Verify 0/4–20 mA or voltage outputs where used.
- Perform sensor simulation or loop testing.
- Confirm alarm and protection logic before returning the machine to service.
Commissioning Checklist
- Confirm A6120 model
- Inspect module and connectors
- Verify CSI 6500 rack compatibility
- Check sensor type
- Verify sensor wiring
- Check 24 VDC supply
- Confirm channel configuration
- Verify frequency range
- Check vibration measurement
- Test analog outputs
- Verify alarm thresholds
- Verify trip/bypass functions
- Record commissioning results
⚠️ Important Identification Note
Some aftermarket listings describe the A6120 simply as a “signal receiving board” or “controller board.” The more accurate technical identification is Case Seismic Vibration Monitor. Emerson’s own documentation clearly identifies A6120 as a two-channel case-seismic vibration monitoring module for the CSI 6500 system.
Also, do not confuse A6120 with other CSI 6500 monitoring cards such as A6110, A6210, A6410, or A6140. They perform different monitoring or protection functions and should not be treated as direct substitutes.
Ordering Information
Emerson A6120 | CSI 6500 | Case Seismic Vibration Monitor | 2-Channel | 3U 1-Slot | Machinery Protection Module
