A6125 (Part No. 9199-00069) is a dual-channel case-mounted piezoelectric vibration monitor card under Emerson’s CSI6500/AMS6500 Machinery Health Monitoring System, formally released in July 2011. Optimized for piezoelectric accelerometers and velocity-type vibration transducers, it delivers online bearing housing vibration monitoring and safety interlock protection for critical rotating machinery. Designed as a single-slot hot‑swappable 3U module and fully compliant with the international API 670 machinery protection standard, it can be freely combined with A6110, A6140, A6210 and other series cards to construct full-set machine protection systems.
The module integrates seamlessly into Emerson PlantWeb digital plant architecture and AMS Suite predictive maintenance platform, with native connectivity to mainstream DCS including DeltaV and Ovation. Widely deployed as a drop-in replacement for legacy seismic-sensor-based monitor modules, it has become the preferred upgrade option for bearing housing monitoring retrofits on nuclear, thermal power and petrochemical turbine units.
This card measures absolute bearing housing vibration (shaft vibration excluded), with readings quantified in acceleration g or vibration velocity mm/s. It captures casing vibration induced by rotor perturbation, structural deformation of equipment housing, gear meshing and mechanical coupling from adjacent machinery, and activates pre-alarm or shutdown relay outputs once readings exceed preset thresholds to enable early equipment fault protection.
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Core Advantages
Optimized Cabinet Footprint
Featuring a 3U single-slot dual-channel architecture, it cuts cabinet space consumption by 50% compared with legacy 6U four-channel monitor cards. Up to 14 A6125 modules can be densely installed in one standard 19-inch rack, lowering cabinet expansion cost and field wiring workload via high-density integration.
Safe & Reliable Hot-Swap Capability
Full-card hot swap allows faulty module replacement without system shutdown to shorten overhaul downtime and satisfy continuous production requirements of refineries and power plants. Compliant with API 670 industrial protection specifications, it is qualified for SIL-rated safety interlock loop deployment.
Full-Loop Built-In Diagnostic Protection
Comprehensive onboard diagnostics monitor hardware health, input power, card temperature, transducer status and field cabling continuously. The system detects transducer open/short circuits, over-temperature and power anomalies, triggering front-panel LED alerts and bus communication alarms simultaneously to eliminate false or missing equipment protection triggered by wiring faults.
Multi-Standard Output for Universal System Integration
Dual buffered raw vibration signals plus industry-standard analog outputs (0/4~20 mA, 0~10 VDC) with ±1% FS accuracy are available alongside Modbus TCP digital communication. Interfaces connect seamlessly to on-site PLC/DCS or CSI4500 portable analyzers for in-situ spectrum analysis.
Streamlined Remote Maintenance
Remote relay contacts support span multiplier adjustment and protection trip bypass without on-site jumper wiring, ideal for temporary protection masking during unit commissioning and standalone equipment maintenance.
Isolated Transducer Power Supply for Enhanced Safety
Constant-current excitation (2~8 mA / 30 VDC) for piezoelectric transducers is galvanically isolated from system power to prevent module burnout caused by transducer short circuits. Built-in open/short protection on the excitation circuit accommodates complicated field wiring conditions.
Product Specifications
(I) Channel & Transducer Input Characteristics
Channel Configuration: 2 independent differential piezoelectric input channels; input impedance＞100 kΩ, input voltage range −5~+15 VDC, peak input 311~9500 mVpp.
Three Hardware Filter Frequency Ranges
| Transducer Type | High Band | Mid Band | Low Band |
|---|---|---|---|
| Piezoelectric Accelerometer | 30~8000 Hz | 10~2000 Hz | 6~1000 Hz |
| Velometer | 10~2000 Hz | 6~1500 Hz | 2~250 Hz |
Excitation: Isolated constant-current source 2~8 mA @30 VDC with auto open/short-circuit protection.Measurement Modes: Per-channel independent configuration supporting RMS or peak-to-peak calculation; user definable transducer sensitivity, alarm span and filter cutoff frequency.
(II) Output Interface Parameters
Front-Panel Output
- Two per-channel green OK LEDs plus four red alarm LEDs for Alert / Danger tiered warning; OK LED extinguishes upon fault while red indicators flash during alarm delay period.
- Front buffered raw waveform: ±12 V, load＞100 kΩ, bandwidth 0.075 Hz~10 kHz (−3 dB ±20%).
- Mini-DIN RS232 port for local parameter setup & status reading; equipped with extraction handle for easy hot swap and label mounting.
Rear-Backplane Output
- Analog Current: Independent 0/4~20 mA per channel, max load＜500 Ω, ±1% FS accuracy, output response 0~10 s software configurable.
- Analog Voltage: Proportional 0~10 VDC output.
- Rear buffered raw waveform: 0~12 Vpp, bandwidth 0.075 Hz~13 kHz, load＞100 kΩ for offline analyzer waveform capture.
- Digital Communication: Modbus TCP; upload amplitude & phase data of 1×, 0.5× and 2~10× rotational frequencies as well as FFT spectrum to AMS software. Dedicated 4-pin CSI4500 socket for plug-and-play portable analyzer connection.
(III) Alarm Logic Setup
Two-Tier Alarm (Alert / Danger): Per-channel NO/NC relay contacts selectable; onboard 0~5 s alarm delay extendable to 0~36 s when paired with A6740 relay card.Span Setting: Alarm threshold adjustable continuously from 5%~100% FS with 1% FS resolution; programmable signal drop hysteresis 0~20% FS to avoid intermittent alarms from minor vibration fluctuation.Interlock Control: Remote alarm suppression available for faulty channels (open transducer / module failure); passive remote contact enables Trip Bypass and Limit Multiply (1.00~4.99× span scaling) to relax protection setpoints temporarily during unit commissioning.
(IV) Mechanical & Environmental Specifications
Form Factor: DIN41494 standard 3U Eurocard: 30 mm(W,6TE)×128.4 mm(H,3HE)×160 mm(D); net weight≈320 g, gross packaged weight 450 g, single-slot mounting.Ingress Rating: Full module IP00, front panel IP21.Temperature & Humidity: Operating: 0~65℃; storage: −30~85℃; RH 5%~95% non-condensing.Vibration & Shock: Compliant with IEC68-2; vibration:10~55Hz@0.15mm,55~150Hz@19.6 m/s²; shock:98 m/s² peak,16 ms duration; EMC certified per EN50081-1/EN50082-2.
Power Consumption: 24 VDC supply, max power 6 W, nominal operating current 250 mA; password protection for parameter modification to prevent unauthorized on-site span changes.
Product Application Scenarios
1. Power Industry (Thermal / Hydro / Nuclear Power Core Applications)
- Nuclear Power: Bearing housing vibration monitoring for reactor circulating pumps and cooling water pumps; case-mounted piezoelectric vibration measurement is the preferred technical route per nuclear industry specifications.
- Thermal Power: Rolling bearing housings of turbo-generator auxiliary equipment, induced draft fans, forced draft fans and coal pulverizers.
- Hydropower: Bearing pedestals and speed-increasing gearbox casings of hydro-turbine generator units, deployed for retrofitting legacy magnetoelectric seismic transducer systems.
2. Petrochemical & Coal Chemical Industry
Online protection for bearing housings of gas turbines, reciprocating compressors, screw compressors, large reduction gearboxes and air separation units. This card is the standard upgrade solution for replacing original magnetoelectric sensors with piezoelectric alternatives; OEM recommends synchronous overhaul consisting of new transducers plus A6125 monitor modules for full system retrofit.
3. Metallurgy, Papermaking & Mining Industries
Condition monitoring for rolling bearing housings of large industrial fans, main sinter exhaust blowers, reduction gearboxes and roller presses to realize early warning of bearing spalling and gear pitting defects.
Model Selection Guidance
A6125 is exclusively designed for absolute bearing housing vibration measurement via piezoelectric transducers and not applicable for relative shaft vibration or shaft displacement monitoring:
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