The IQS900 Signal Conditioner is a high-performance, modular, core component of the non-contact eddy current displacement measurement system from Meggitt's vibro-meter product line. This product works in conjunction with the TQ402/TQ412 series eddy current sensors and the EA402 extension cable to form a complete displacement/vibration measurement system. It is widely used for real-time measurement of parameters such as relative shaft vibration, axial displacement, eccentricity, and rotational speed in rotating machinery, including steam turbines, compressors, pumps, and generators.
The IQS900 is the upgraded replacement for the IQS450, featuring higher electromagnetic compatibility, enhanced interference immunity, lower output impedance, and supports SIL 2 functional safety design. It is suitable for long-term, stable operation in harsh industrial environments such as automation, petrochemicals, power generation, and metallurgy.
The specific model IQS900 204-900-000-011 A1-B23-C1-H05-I0 is a high-precision, Ex-certified, standard signal conditioner with voltage output and no diagnostic functions. It is suitable for installation in Zone 2 hazardous areas, supports DIN-rail mounting, and is widely used in protection systems conforming to API 670 standards.
II. Product Features
Non-contact eddy current measurement principle, suitable for dynamic and static measurements of high-speed rotating machinery.
Supports 1 m, 5 m, and 10 m total system lengths, with flexible cable combinations.
Temperature-compensated design ensures stability across the full temperature range.
Frequency response range DC ~ 20 kHz, suitable for vibration and displacement measurements.
Voltage output (4 mV/μm) , suitable for a 4 mm measurement range.
Low output impedance down to 100 Ω, supporting long-distance transmission.
SIL 2 functional safety design (complies with IEC 61508).
Explosion-proof certifications: ATEX, IECEx, CCSAus, KGS, EAC, etc.
Supports DIN-rail mounting for easy installation and maintenance.
Plug-in screw terminals simplify on-site wiring.
III. Model Code Breakdown (IQS900 204-900-000-011 A1-B23-C1-H05-I0)
| Code Segment | Description |
| 204-900-000-011 | Base model and version number |
| A1 | Standard version, no Ex certification (this model is A1, but this description references the A5 option for Ex applications) |
| B23 | System configuration: 4 mm measurement range, voltage output (4 mV/μm) |
| C1 | Version without diagnostic functions |
| H05 | Housing and mounting: Standard metal housing, supports DIN-rail mounting |
| I0 | Standard connector configuration, no special interface requirements |
IV. System Composition and Operating Principle
The IQS900 Signal Conditioner, together with the TQ402/TQ412 sensor and EA402 cable, forms a complete eddy current displacement measurement system. Its operating principle is as follows:
Sensor Excitation: The internal high-frequency oscillator in the IQS900 generates an excitation signal that drives the sensor coil, creating a high-frequency electromagnetic field.
Target Interaction: When a metallic target (e.g., a shaft) approaches the sensor tip, the electromagnetic field induces eddy currents on the target surface. These currents react back on the sensor coil, altering its impedance.
Demodulation and Output: The modulation/demodulation circuit inside the IQS900 converts this impedance change into an output signal (voltage or current) proportional to the gap.
Signal Transmission: The output signal can be directly connected to monitoring systems like VM600, VibroSmart, etc., for protection, control, and diagnostics.
V. Typical Applications
Steam Turbines, Hydraulic Turbines, Gas Turbines: Shaft vibration, axial position monitoring.
Compressors, Blowers: Rotor dynamic behavior analysis.
Pumps: Eccentricity, rotational speed, vibration monitoring.
Generators, Electric Motors: Shaft vibration and gap monitoring.
API 670 Standard Protection Systems: Rotating machinery protection systems conforming to international standards.
Hazardous Areas: Condition monitoring in Zone 2 explosive environments.
VI. Total System Length and Cable Combinations
| Total System Length | Sensor Cable | Extension Cable |
| 1 m | 1.0 m | None |
| 5 m | 0.5 m / 1.0 m / 1.5 m / 2.0 m / 5.0 m | 4.5 m / 4.0 m / 3.5 m / 3.0 m / None |
| 10 m | 0.5 m / 1.0 m / 1.5 m / 2.0 m / 5.0 m / 10.0 m | 9.5 m / 9.0 m / 8.5 m / 8.0 m / 5.0 m / None |
Note: All cables require electrical length trimming to ensure system interchangeability and accuracy.
VII. Explosion-Proof Certification Information
| Certifying Body | Standard | Explosion Protection Level |
| ATEX | LCIE 21 ATEX 3002 X | Ex ia IIC T6/T5 Ga |
| IECEx | IECEx LCIE 21.0006X | Ex ia IIC T6/T5 Ga |
| CCSAus | 80084516 | Class I, Div 1, Groups A-D |
| KGS | 21-GA4BO-0353X | Ex ia IIC T6/T5 Ga |
| EAC | EA3C RU C-CH.AAD07.B.03744/21 | 0Ex ia IIC T6/T5 Ga X |
Note: This specific model with code A1 is the standard, non-Ex version. For Ex applications, the A5 option code should be selected.
VIII. Accessories and Mounting Aids
| Accessory Name | Model | Description |
| DIN-rail Mounting Adapter | MA130 | 809-130-000-021, for mounting IQS900 |
| Industrial Protection Enclosure | ABA17x | Enhances ingress protection rating to IP54 or higher |
| Interconnection Protector | IP172 | Protects the connection point between sensor and cable |
| Flexible Conduit | KS107 | Provides mechanical protection |
| Probe Mounting Adapter | PA15x | For sensor positioning and installation |
| Cable Feedthrough | SG1xx | For introducing cables into cabinets |
IX. Compatible Systems
VM600 / VM600 Mk2 Series Monitoring Modules
VibroSmart® Distributed Monitoring System
GS1127 Galvanic Isolation Unit
Third-party PLC/DCS Systems (must match input impedance requirements)
X. Ordering Information
| Component | Model | Description |
| Signal Conditioner | IQS900 204-900-000-011 A1-B23-C1-H05-I0 | 4 mm, voltage output, no diagnostics, standard type |
| Sensor | TQ402 / TQ412 | Select based on mounting requirements |
| Extension Cable | EA402 | Length options: 0.5 m ~ 10 m |
| Mounting Adapter | MA130 | Optional |
