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

European LCIE 11 ATEX 1010 X, II 3G (Zone 2), Ex nA II T6... T3 Gc

International IECEx LCI 11.0063X, Ex nA II T6... T3 Gc

North American CCSAus certificate 1514309, Class I, Division 2, Groups A, B, C, D

Important reminder: When using Ex nA spark free protection mode, users must ensure that the signal conditioner is installed in a chassis with a protection level of at least IP54.

5. System length configuration and cable options

5.1 Total System Length (TSL)

Total system length=TQ 422/432 sensor integrated cable length+EA 402 extension cable length

Standard Total Length Options:

1 meter: 1.0 meter integrated cable (without extension cable)

5 meters: 1.0 meter integrated+4.0 meter extension cable; Or 5.0 m integrated (without extension cable)

10 meters: 1.0 meter integrated+9.0 meter extension cable; Or 5.0 m integrated+5.0 m extension cable; Or 10.0 m integrated (without extension cable)

5.2 Cable length adjustment

Due to the electrical characteristics of coaxial cables, in order to optimize system performance and sensor interchangeability, it is necessary to perform "electrical trimming" on the nominal length:

1 meter measuring chain: minimum total system length of 0.9 meters

5-meter measuring chain: minimum total system length of 4.4 meters

10 meter measuring chain: minimum total system length of 8.8 meters

5.3 Cables and Connectors

Cable type: FEP sheathed 70 Ω coaxial cable, outer diameter 3.6 mm

Connector: self-locking micro coaxial connector (manually twisted to lock when connected)

Optional protection:

Flexible stainless steel hose (TQ 422/432): provides additional mechanical protection and has leak proof properties

FEP sheath (EA 402): resistant to chemicals, low permeability, low friction, high mechanical strength

6. Sensor installation and mechanical dimensions

6.1 TQ 422 Sensor (Standard Installation)

Thread specification: metric thread

Installation method: Directly installed on the equipment housing through threads

Integrated cable: led out from the tail of the probe, with optional length

6.2 TQ 432 Sensor (Reverse Installation)

Thread specification: metric thread

Installation method: Reverse installation design, suitable for application scenarios with limited installation space

Integrated cable: led out from the tail of the probe, with optional length

6.3 Installation of IQS 450 signal conditioner

Standard installation: fixed with two or four M4 screws

MA 130 installation adapter (ordering option 11): Universal DIN rail installation, compatible with TH 35-7.5 or TH 35-15 type rails (compliant with EN 50022/IEC 60715)

7. Thermal derating characteristics

The IQS 450 signal conditioner can operate at ambient temperatures up to 85 ° C, but requires derating of the maximum input voltage. The system must operate between the minimum and maximum supply voltages, and the specific derating curve is shown in the following figure:

Maximum supply voltage for ambient temperature

25°C -32 V

85 ° C-24 V (approximately)

Note: When operating in high temperature environments, it is necessary to ensure that the power supply voltage does not exceed the allowable value after derating to ensure system stability and reliability.

8. Calibration and Target Materials

8.1 Factory calibration

Calibration temperature:+23 ° C ± 5 ° C

Target material: VCL 140 steel (1.7225)

8.2 Special Calibration Requirements

For precise measurement of non-standard materials, customers can:

Clearly specify the alloy composition of the target material

Provide sample materials (minimum size: diameter 50 mm, thickness 10 mm) prepared according to Meggitt Sensing Systems drawing number PZ 7009/1

9. Application scenarios and system integration

9.1 Typical Applications

Turbine monitoring: shaft vibration, axial displacement, and blade clearance monitoring of Kaplan and Francis turbines

Submersible pump monitoring: rotor vibration and position monitoring of submerged pumps

High pressure compressor: shaft relative vibration and axial position monitoring

General rotating machinery: shaft vibration, eccentricity, thermal expansion monitoring

9.2 System Integration

The TQ 422/TQ 432 proximity measurement system can be seamlessly integrated with the following equipment:

VM600 series mechanical protection system: directly connected through IOC4T input/output card, providing voltage or current signal input

Other signal processing modules: compatible with standard 4-20 mA or -2.4 V to -18.4 V input data acquisition systems

Power supply method:

Directly powered by signal processing modules such as VM600 (-20 V to -32 V)

Powered by an external DC power source (must comply with explosion-proof safety requirements)

10. Maintenance and Precautions

10.1 Installation precautions

Connector handling: Self locking micro coaxial connectors should be hand screwed to lock and should not be over tightened with tools

Cable protection: It is recommended to use flexible stainless steel hoses or FEP sheaths to protect cables in high temperature, high pressure, or corrosive environments

Target material: The target must be a metallic material, either non-magnetic or ferromagnetic, but with different sensitivity characteristics

10.2 Precautions for Explosion proof Applications

Ex i intrinsic safety type: The system can be used in Zone 0, 1, and 2 areas and must comply with relevant installation specifications

Ex nA spark free type: The signal conditioner must be installed in a chassis with a protection level of IP54 or higher

Certificate inquiry: For specific explosion-proof parameters and safety usage conditions, please refer to the explosion-proof certificate provided by Meggitt SA

10.3 System interchangeability

All components (sensors, signal conditioners, extension cables) are interchangeable and do not require recalibration. This feature greatly simplifies on-site maintenance and spare parts management.