The A6620 Dual-Channel Eccentricity Monitor Card (Part No. 9199-00086) is part of Emerson CSI6500 Machinery Health equipment condition monitoring system. Developed and released in July 2011 as a hot-swappable single-slot 3U module compliant with API 670 machinery protection specifications, it is custom-engineered for online eccentricity monitoring of large rotating equipment with plain bearings.
As a core hardware component of Emerson PlantWeb digital plant architecture and AMS asset management suite, the card can be combined with the full CSI6500 card lineup to build complete machinery protection systems. It enables condition data intercommunication with mainstream DCS platforms including DeltaV and Ovation. Optimized for low-speed rotating equipment below 600 rpm, it continuously collects rotor bow and shaft eccentricity measurements and triggers protection interlocks upon alarm thresholds, paired with eddy-current non-contacting displacement transducers for eccentricity acquisition.Featuring an independent dual-channel measurement design, it replaces legacy 6U four-channel monitor boards and cuts cabinet space occupancy by 50%. It serves as standard equipment for predictive maintenance and safety interlock protection on critical turbines across thermal power, oil & gas and hydropower industries.
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Core Advantages
Compliant & Highly Reliable Construction
Fully compliant with mandatory API 670 machinery protection standards. Hot-swap capable for online module replacement without rack-wide shutdown, eliminating unplanned unit outages and satisfying mandatory interlock specifications for thermal power and petrochemical rotating equipment.
Compact Footprint for Space Savings
3U single-slot (6TE) DIN Eurocard form factor allows dense installation of up to 14 modules within one standard 19-inch rack. It reduces cabinet space usage by half versus legacy 6U four-channel monitor cards, ideal for compact control cabinet retrofit projects.
Full-Loop Self-Diagnosis to Prevent False Alarms
Comprehensive onboard diagnostic circuitry continuously monitors module hardware, power supply, card temperature, external transducers and field cabling. Fault alerts are indicated via front-panel LEDs and uploaded over system bus to avoid false alarms or missed protection trips caused by broken cables or defective probes.
Multiple Standardized Signal Outputs
Dual buffered analog outputs plus industry-standard 0/4–20 mA and 0–10 VDC transmitter outputs enable seamless integration with DCS, PLC and local digital indicators. Native compatibility with Emerson AMS predictive diagnostic software supports remote trending and early fault prediction of eccentricity data.
Remote Maintenance & Parameter Control
Remote gain adjustment (1.00~4.99× span amplification) and remote interlock trip bypass are supported; temporary parameter modification is achievable without on-site cabinet opening or rewiring during unit commissioning and startup.
Rugged Wide-Range Environmental Tolerance
Wide operating temperature/humidity plus shock and vibration resistance for long-term stable operation in high-temperature, humid and high-EMI environments typical of power plants and refineries; EMC performance meets European EN standards.
Product Specifications
(I) Mechanical Structure & Electrical Specifications
Dimensions: Standard DIN41494 Eurocard PCB; overall dimension 100×160 mm, width 30 mm (6TE), height 128.4 mm (3HE). Net weight approx. 320 g; gross weight with package 450 g. Single-slot mounting; up to 14 modules mountable per standard 19-inch rack.
Power & Power Consumption: Rated 24 VDC supply; max total power consumption 6 W, nominal operating current 250 mA. An isolated onboard probe supply (nominal −26.7 VDC, rated output 20 mA, peak 35 mA) is galvanically separated from system power with built-in protection against open/short-circuit of transducer wiring.
Channel Configuration: Two fully isolated differential inputs for eddy-current transducers. The two channels feature complete galvanic isolation with no mutual interference; input circuitry is isolated from system power with input impedance >100 kΩ. Compatible with Emerson 6422/6423/6424/6425 eddy-current displacement probes, used together with CON-series preamplifiers and keyphasor monitor modules.
(II) Measurement Performance Parameters
Input Frequency: 0.017~70 Hz (corresponding rotational speed: 102~4200 rpm), optimized for low-speed eccentricity monitoring below 600 rpm during unit startup & shutdown.
Measurement Range: Continuously adjustable via host configuration software; minimum full scale: 0~400 mV peak, maximum full scale: 0~8000 mV peak. Three selectable calculation modes: peak-to-peak, max/min value and continuous gap measurement. User-defined engineering units and transducer sensitivity parameters are supported with hot online configuration; updated settings stabilize within 60 seconds.
Output Specifications
- Rear-side Current Output: Independent 0/4~20 mA per channel with open/short protection; permissible load <500 Ω, full-scale accuracy ±1%. Filter settling time configurable from 0~10 s via software.
- Rear-side Voltage Output: Independent 0~10 VDC per channel, minimum load impedance >10 kΩ, accuracy ±1% FS.
- Front & Rear Buffered Raw AC/DC Output: Bandwidth 0 Hz~16 kHz (−3 dB), load >10 kΩ, for off-line diagnosis via external fault analyzers.
Alarm Logic: Three relay alarm levels: Alert, Danger and OK; relay contacts configurable as normally open or normally closed. In-channel Alert/Danger delay adjustable 0~5 s, extendable to 0~36 s when paired with A6740 relay card. Alarm threshold settable from 5%~100% FS with 1% FS resolution; signal drop hysteresis programmable 0~20% FS, and alarm suppression available for faulty channels. The OK circuit is normally closed; the front-panel green OK LED turns off and status indicators blink during delay phase upon any fault including power failure, probe fault, cable break, over-temperature or overload. Fault codes are retrievable over RS232 bus.
Remote Control Function: Remote control contacts enable Limit Multiplier (1.00~4.99×) and Trip Bypass for temporary interlock removal during unit commissioning and trial run.
(III) Environmental Specifications
| Item | Specification |
|---|---|
| Ingress Protection | Front panel IP21, main card IP00 per DIN40050 |
| Operating Temperature | 0℃~65℃ (32℉~149℉); Storage & transit: −30℃~85℃ |
| Ambient Humidity | 5%~95% RH, non-condensing |
| Vibration Resistance | IEC68-2-6: 10~55 Hz @ 0.15 mm amplitude; 55~150 Hz @ 19.6 mm/s² acceleration |
| Shock Resistance | IEC68-2-29: peak acceleration 98 m/s², pulse duration 16 ms |
| EMC Compliance | EN50081-1 / EN50082-2 industrial EMC standards |
(IV) HMI & Configuration Interface
Front Panel: Two green OK LEDs plus four graded red/yellow/green alarm LEDs per channel; Mini-DIN RS232 configuration port for dedicated programming handset supporting local parameter setup and status reading.Access Control: Password protection for system parameter settings to prevent unintended on-site modification of protection setpoints.
Application Scenarios
1. Target Industries
Thermal power (steam turbine generator sets), gas turbine packages, reciprocating & centrifugal process compressors, and hydroelectric turbine units, covering all heavy rotating machinery fitted with large plain bearings.
2. Monitoring Purposes
Low-Speed Operation During Unit Startup/Shutdown (<600 rpm)
Continuously monitor rotor sag from gravitational load, thermal deformation deflection and inherent manufacturing eccentricity. An over-limit eccentricity reading prohibits unit speed-up to prevent catastrophic equipment faults such as rotor rubbing and bearing wipe; eccentricity supervision during steam turbine startup is a mandatory interlock item per unit protection logic.
Online Predictive Maintenance
Long-term continuous trending of eccentricity enables early warning of bearing wear, rotor misalignment and permanent rotor bow to facilitate scheduled overhaul and eliminate unplanned sudden shutdowns.
Interlock Protection
Once eccentricity hits Danger threshold, onboard or external A6740 relay cards initiate trip commands to trigger emergency shutdown of lube oil systems, main steam stop valves or compressor inlet valves, fully complying with API 670 machinery protection requirements.
FAQ
Q1: What is the correlation between A6620 and A6220? Does part number 9199-00086 refer to the identical product?A: A6220 is the official model designation while A6620 is a project-specific part code; 9199-00086 is the unique stock part number for this module. All three identifiers stand for the same dual-channel eccentricity monitor card. Factory marking is printed as A6220 and the warehouse inventory code is 9199-00086; either number is acceptable for purchasing orders.
Q2: Is original Emerson 6422~6425 transducer mandatory? Are third-party eddy-current probes compatible?A: The hardware circuit can physically accept differential eddy-current probes of matching footprint, yet API 670-certified protection projects and Emerson AMS traceability rules require genuine OEM 64XX series probes. Third-party probes feature inconsistent sensitivity and supply matching, resulting in inaccurate scaling, self-test failures and spurious alarm trips; non-OEM probes are not recommended for critical unit protection applications.
Q3: Maximum quantity of A6620 per standard 19” rack? Does companion A6740 relay card consume extra rack slots?A: Standard CSI6500 rack holds 14 slots for up to 14 pieces of A6620. The A6740 is an external relay terminal assembly occupying no monitor card slots and mounted within the lower wiring compartment of the rack.
Q4: What spare parts are required for API 670-compliant procurement?A: Standard package: main module (9199-00086) + front panel nameplate cover. Optional accessories: RS232 configuration cable, 64XX eddy-current probe plus preamplifier, A6740 relay output card and rack power supply module.
Q5: Front-panel green OK LED turns off, how to troubleshoot faults?A: Extinguished OK LED indicates self-test failure, troubleshoot sequentially:① Inspect 24VDC input for phase loss or undervoltage;② Check both transducer cables for open or short circuit;③ Power down, extract the card to clear slot dust then perform hot reinsertion;④ Retrieve fault codes via RS232 interface to distinguish between internal hardware damage or field transducer failure.
Q6: Deviation between 4~20mA output and actual field eccentricity exceeds 3%, corrective actions?
- Recheck configured transducer sensitivity and measurement range parameters via configuration software;
- Verify rear-end load resistance not exceeding 500Ω maximum rating;
- Recalibrate installation air gap of eddy-current probes on site;
- Refit wiring for transducer power feed loop.
Q7: Frequent false eccentricity alarms only at low startup speed below 600 rpm with normal readings at rated speedLow-speed range is the designated eccentricity measurement window, typical root causes:① Improperly low alarm threshold setting;② Worn target eccentric ring under the probe;③ Loose wiring induced by startup vibration.Solutions: moderately raise Alert threshold, remeasure probe gap and fasten shielded cabling.
Q8: How to remotely bypass interlock protection temporarily for maintenance?Wire passive dry contact switch to the Remote terminal on module rear edge; closing the switch activates remote Trip Bypass without modifying alarm setpoints; interlock automatically restores once contact opens after maintenance completion.
Q9: Does the card support hot swap? What precautions apply during plug/unplug?Hot swapping is permitted under API 670 specifications. Bypass relevant channel interlock remotely before card replacement to avoid spurious unit tripping from transient signal disturbance; never hot-plug transducer field wiring.
Q10: Recurring over-temperature warnings in hot summer ambient conditionsInsufficient cabinet ventilation; install rack axial cooling fans. Optimize cabinet air circulation if ambient exceeds 65℃ and avoid direct sunlight exposure on equipment racks.
Q11: Measurement frequency covers 102~4200 rpm, usable for high-speed units over 4200 rpm?A6620 is purpose-built exclusively for low-speed eccentricity monitoring (<600 rpm during startup/shutdown). Select general-purpose vibration monitor cards from the same CSI6500 product family for high-speed rotor vibration measurement instead.
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