MEGGITT TQ TQ 422/432 Eddy Current Measurement System

TQ 422/TQ 432 Eddy Current Proximity Measurement System: Precise Monitoring Solution in High Voltage Environment

1. Introduction

The change in clearance between the rotor and stator during the operation of rotating machinery (such as steam turbines, water turbines, compressors, pumps, etc.) is a key indicator reflecting the health status of the equipment. Eddy current proximity measurement technology utilizes the principle of electromagnetic induction to measure the distance between metal targets and sensor probes in a non-contact manner. It has the advantages of wide frequency response range, strong anti-interference ability, and adaptability to harsh environments.

The TQ 422 and TQ 432 eddy current sensors, together with the IQS 450 signal conditioner, form a complete, factory calibrated proximity measurement system. This system is designed specifically for high-pressure applications, with sensor probes capable of withstanding pressures up to 100 bar, making it particularly suitable for monitoring key parameters of equipment such as submersible pumps, Kaplan turbines, Francis turbines, etc.

2. System composition and working principle

2.1 System Architecture

The TQ 422/TQ 432 proximity measurement system consists of the following core components:

TQ 422/TQ 432 eddy current sensors: non-contact probes with coils encapsulated inside, molded from PEEK (polyetheretherketone) material, and the probe body is made of stainless steel material.

IQS 450 signal conditioner: Built in high-frequency modulation/demodulation circuit, providing excitation signals for sensors and converting measurement signals into voltage or current outputs.

EA 402 extension cable: an optional component used to extend the distance between sensors and signal conditioners.

Installation accessories: Optional enclosures, junction boxes, connection protectors, etc. provide mechanical and environmental protection for cable connections.

2.2 Working principle

The eddy current proximity measurement system operates based on the principle of electromagnetic induction. The IQS 450 signal conditioner provides high-frequency excitation signals to the sensor probe coil, generating an alternating electromagnetic field around the coil. When a metal target (such as a rotating shaft) approaches the probe, an eddy current is generated on the surface of the target, and the intensity of this eddy current is inversely proportional to the distance between the probe and the target. The change in eddy current will have a reverse effect on the impedance of the coil. The signal conditioner detects this impedance change and converts it into a voltage or current signal output proportional to the distance.

3. Technical specifications and performance parameters

3.1 Overall System Performance

Parameter specifications

Sensitivity option B21: 8 mV/μ m (200 mV/mil)

Option B22: 2.5 μ A/μ m (62.5 μ A/mil)

Option B23: 4 mV/μ m (100 mV/mil)

Option B24: 1.25 μ A/μ m (31.2 μ A/mil)

Linear measurement range 0 to 2.0 mm (B21/B22)

0 to 4.0 mm (B23/B24)

Linearity refers to the performance curve

Frequency response DC to 20 kHz (-3 dB)

System interchangeability: All components are interchangeable without the need for recalibration

3.2 Output and Power Supply

Voltage output (3-wire system):

Minimum gap voltage: -2.4 V

Maximum gap voltage: -18.4 V

Dynamic range: 16 V

Output impedance: 500 Ω

Short circuit current: 45 mA

Current output (2-wire system):

Minimum gap current: -15.5 mA

Maximum gap current: -20.5 mA

Dynamic range: 5 mA

Output capacitance: 1 nF

Output inductance: 100 μ H

Power supply requirements:

Supply voltage: -20 V to -32 V

Voltage output mode current: -13 mA ± 1 mA (maximum -25 mA)

Current output mode: -15.5 mA to -20.5 mA

3.3 Environmental and Mechanical Specifications

TQ 422/TQ 432 sensors:

Working temperature: -25 ° C to+140 ° C (temperature drift<5%)

Explosion proof environment temperature: -40 ° C to+195 ° C (Ex certified)

Cable withstand temperature: -40 ° C to+200 ° C

Maximum pressure: 100 bar at the tip of the probe; 10 bar with flexible hose; 1 bar without hose

Protection level: probe tip and integrated cable IP68

Vibration tolerance: 5 g peak (10-500 Hz)

Impact tolerance: 15g peak (half sine wave, 11ms)

Probe structure: 8mm coil, PEEK tip, stainless steel housing (1.4435)

IQS 450 signal conditioner:

Working temperature: -35 ° C to+85 ° C

Storage temperature: -40 ° C to+85 ° C

Humidity: Maximum 95% non condensing, 100% condensing (non submerged)

Protection level: IP40

Shell material: injection molded aluminum

Weight: Standard version about 140 g, explosion-proof version about 220 g

4. Explosion proof certification and safety application

The TQ 422/TQ 432 proximity measurement system offers multiple explosion-proof certification options, suitable for explosive hazardous environments:

4.1 Ex i intrinsic safety type (ordering option A2)

Certification Area Certificate/Standard

European LCIE 11 ATEX 3091 X, II 1G (Zone 0, 1, 2), Ex ia IIC T6... T3 Ga

International IECEx LCI 11.0061X, Ex ia IIC T6... T3 Ga

North American CCSAus certificate 1514309, Class I, Divisions 1 and 2, Groups A, B, C, D，Ex ia

4.2 Ex nA spark free type (ordering option A3)

Certification Area Certificate/Standard