System Overview
Meggitt Vibro-Meter TQ402/TQ412, EA402 and IQS900 form a non-contact eddy-current proximity measurement system for the relative displacement of moving machine elements. The TQ402 or TQ412 probe senses the distance to a metallic target, the EA402 provides the specified extension length, and the IQS900 supplies high-frequency excitation before converting the probe response into a monitor-side voltage or current signal.
For a shaft vibration or axial-position channel, Meggitt Vibro-Meter TQ402/TQ412 places the sensing coil at the machine target. The conditioner then produces an output proportional to the measured gap. This chain is intended for machinery protection and condition monitoring on steam, gas and hydraulic turbines, alternators, turbo-compressors and pumps.
The practical configuration question is not only which probe body fits the mounting point. The installation must also keep the selected 2 mm or 4 mm range, total cable length, target material, output type, environmental limits and area approval consistent across Meggitt Vibro-Meter TQ402/TQ412, EA402 and IQS900.
1. Select the Probe Orientation
TQ402 standard mount
Meggitt Vibro-Meter TQ402 uses the standard mounting arrangement. Check the available threaded body length, unthreaded length, probe-tip clearance and the direction in which the integral coaxial cable leaves the mounting point. The ordering structure provides metric and imperial thread choices, body lengths from 20 to 250 mm, unthreaded lengths from 0 to 230 mm and integral cable options from 0.5 to 10 m.
TQ412 reverse mount
Meggitt Vibro-Meter TQ412 is the reverse-mount version for a mounting point where the standard probe direction is not suitable. The mechanical drawing shows the reverse-body ordering structure, including M10 × 1 or 3/8 in–24 UNF threads, integral cable lengths and the same 1 m, 5 m or 10 m total-system-length choices.
Both Meggitt Vibro-Meter TQ402 and Meggitt Vibro-Meter TQ412 use a stainless-steel body, a Torlon® tip with an internal coil, an integral coaxial cable and a self-locking miniature coaxial connector. The target must be metallic, and the probe gap must remain inside the selected linear measurement range during operation.
2. Technical Data That Changes the Configuration
The measurement range, sensitivity and output style are linked. Use the following values to keep the Meggitt Vibro-Meter TQ402/TQ412 probe and IQS900 ordering options aligned.
| Configuration item | Data-sheet value | Engineering check |
|---|---|---|
| Measurement range | 2 mm or 4 mm | Confirm the stopped gap and running displacement stay within the selected range. |
| 2 mm voltage sensitivity | 8 mV/µm, IQS900 option B21 | Use when the monitor input is specified for voltage output. |
| 2 mm current sensitivity | 2.5 µA/µm, IQS900 option B22 | Use when the channel is wired as a two-wire current loop. |
| 4 mm voltage sensitivity | 4 mV/µm, IQS900 option B23 | Keep the 4 mm probe and conditioner range together. |
| 4 mm current sensitivity | 1.25 µA/µm, IQS900 option B24 | Confirm the receiving monitor accepts the selected current scale. |
| Frequency response | DC to 20 kHz, −3 dB | Provides bandwidth for shaft vibration and position channels. |
| Probe temperature | −40 to +180 °C | Check the probe body and cable route at the machine location. |
| IQS900 operating temperature | −40 to +85 °C | Use an appropriate enclosure when the conditioner is outside its indoor rating. |
| IQS900 supply | −18 to −30 VDC for current output; −19 to −30 VDC for voltage output | Verify the power source and polarity at the conditioner terminals. |
| Maximum IQS900 consumption | 25 mA at nominal 24 VDC | Check the available sensor-supply capacity. |
| Total system length | 1 m, 5 m or 10 m | Combine the integral probe cable and EA402 extension cable. |
| Calibration target | VCL 140 steel, material 1.7225 | Use the specified target for the stated calibration performance. |
3. EA402 Cable Planning and IQS900 Signal Conditioning
Meggitt Vibro-Meter EA402 is the extension-cable element in the TQ4xx chain. Its coaxial construction and optional flexible hose, FEP sheath or IP172 protection must be selected with the probe’s integral cable. The combined length is trimmed to the required total system length rather than treated as an arbitrary field cable.
At the control-panel side, Meggitt Vibro-Meter IQS900 receives the sensor-side signal through its self-locking miniature coaxial connector. Removable screw terminals provide the monitor-side measurement output and −24 V/COM power input, while the separate input connector provides RAW/COM and TEST/COM connections.
Voltage or current output
The IQS900 voltage-output configuration uses three-wire transmission and the current-output configuration uses two-wire transmission. Both outputs include short-circuit and overvoltage protection, but the receiving monitor, barrier and power arrangement must be selected for the chosen output mode.
Diagnostic and test paths
When the diagnostic option is selected, the IQS900 can detect and remotely indicate problems in the sensor, cable or conditioner. The RAW output and TEST input expose additional points for commissioning and signal checks, while the monitor-side output continues to carry the configured measurement signal.
4. System Integration and Installation Boundaries
In a complete channel, the metallic shaft or target is the measured surface, the Meggitt Vibro-Meter TQ402/TQ412 converts the gap into a probe response, the EA402 maintains the specified electrical chain length, and the IQS900 delivers the conditioned signal to a machinery-monitoring input. The system is intended for use with VM600 and/or VibroSmart monitoring and protection systems when the input and supply requirements are matched.
The probe body, extension cable and conditioner have different environmental limits. The TQ402/TQ412 probe range is −40 to +180 °C, while the IQS900 is rated for −40 to +85 °C, 0–95% non-condensing humidity and IP20 unless installed in a higher-protection industrial enclosure. A DIN-rail option is available through the MA130 adaptor for compatible TH 35 rails.
For hazardous-area installations, select the Ex option for the relevant TQ402, TQ412, EA402 or IQS900 component and verify the enclosure, barrier and area classification as one installation. The stated approvals include ATEX, IECEx and other regional schemes; the exact protection mode belongs to the ordered configuration.
Frequently Asked Questions
What is the difference between TQ402 and TQ412?
How do I select a 2 mm or 4 mm IQS900 range?
How is the EA402 total length calculated?
Which target is used for calibration?
What does the IQS900 RAW or TEST connection do?
Which monitor systems can receive the signal?
Data-Sheet Reference
The technical diagrams and configuration values in this article are taken from the English Meggitt Vibro-Meter data sheet: TQ402/TQ412, EA402 and IQS900 proximity measurement system data sheet.
Contact & Enquiry
Send the complete model, configuration and requested quantity for a focused quotation.
Measurement Concept
This generated editorial visual maps the three named product families in the article: Meggitt Vibro-Meter TQ402/TQ412 proximity probe, EA402 extension cable and IQS900 signal conditioner. It is a conceptual relationship diagram, not an official product photograph, dimensional drawing or wiring diagram.
Recommended Products
Mixed-brand catalogue references for proximity sensing, vibration monitoring, signal conditioning and industrial control. These are reference products for further review, not claims of direct electrical interchangeability with every TQ402/TQ412, EA402 or IQS900 configuration.