SIEMIENS PFT6 series weighing sensor



SIEMIENS PFT6 series weighing sensor

Product core positioning

The PFT6 series is a strain gauge weighing sensor designed for harsh industrial environments. Its core advantages are high precision, high protection, and strong anti-interference ability. It is suitable for scenarios with strict requirements for weighing accuracy, such as batching systems and trade settlement belt scales. The range covers 10kg-5000kg and can meet the needs of industrial weighing from light to medium.

Product principle and core features

1. Measurement principle

Based on the effect of resistance strain gauges, the core structure consists of a metal elastomer and resistance strain gauges attached to the elastomer

When the sensor is subjected to a load, the metal elastomer undergoes slight deformation;

Strain gauges undergo resistance changes with the deformation of the elastic body (stretching → increasing resistance, compression → decreasing resistance);

Convert the resistance change into a voltage signal (rated output 2mV/V) through a Wheatstone bridge, and transmit it to the weighing instrument for data processing.

2. Core Features

High precision level: C3 level in accordance with OIML R60 standard (suitable for medium to high precision weighing, division value ≤ 3000), ensuring the accuracy of trade settlement and industrial batching;

High protection performance: The conventional model has a protection level of IP67 (dustproof, anti short-term immersion), and the special customized model can reach IP68 (no damage after soaking in 1m underwater for 24 hours), suitable for harsh industrial environments such as dust and humidity;

Wide temperature adaptability: Temperature compensation range of * * -10 ℃~+40 ℃ (ensuring stable accuracy within this range), working temperature range of -30 ℃~+60 ℃ * *, suitable for high and low temperature industrial scenarios;

Anti interference capability: The single ended grounding design of the cable shielding layer reduces electromagnetic interference (EMC) and is suitable for industrial strong electromagnetic environments;

Overload protection: Safe overload capacity of 150% rated load (R.C.), ultimate overload capacity of 300% R.C., to avoid permanent damage caused by accidental overload.

Key technical parameters

1. Range and accuracy parameters

Range (R.C.) Accuracy level Nonlinear (≤±% R.O.) Lag (≤±% R.O.) Repeatability (≤±% R.O.) Sensitivity Temperature drift (≤±% R.O./℃)

10kg-50kg OIML C3 0.02 0.02 0.01 0.0005

100kg-200kg OIML C3 0.02 0.02 0.01 0.0005

500kg-1000kg OIML C3 0.02 0.02 0.01 0.0005

2000kg-5000kg OIML C3 0.02 0.02 0.01 0.0005

Note: R.O. (Rated Output)=Rated Output, R.C. (Rated Capacity)=Rated Load

2. Electrical parameters

Parameter Category Specific Indicator Remarks

Rated output 2mV/V ± 0.1% based on 10V DC excitation voltage

The resistance between the excitation terminals of the input resistor 380 Ω± 20 Ω

The resistance between the output resistor 350 Ω± 5 Ω signal terminals

Insulation resistance ≥ 5000M Ω (50V DC) between the measuring end and the casing

Excitation voltage 5V DC-15V DC, recommended 10V DC, maximum not exceeding 15V DC

Maximum excitation current of 10mA to avoid excessive excitation current causing strain gauge heating

3. Environmental and mechanical parameters

Parameter category specific indicator standard basis

Working temperature range -30 ℃~+60 ℃ IEC 60068-2-1/2

Temperature compensation range -10 ℃~+40 ℃ OIML R60

Humidity adaptation ≤ 95% RH (non condensing) IEC 60068-2-3

Protection level IP67 (conventional), IP68 (customized) IEC 60529

Allowable lateral force ≤ 10% R.C. Siemens design specifications

Allowable torque ≤ 10% R.C. Siemens design specifications

Vibration tolerance 50Hz, 10m/s ² (10-2000Hz) IEC 60068-2-6

Impact withstand 100m/s ² (11ms) IEC 60068-2-27

Installation and connection specifications

1. Preparation before installation

Environmental inspection: Confirm that the installation environment temperature and humidity meet the parameter requirements, there are no corrosive gases or strong magnetic fields (if additional protection is required);

Load confirmation: Ensure that the actual weighing load is within the range of the sensor (avoid long-term close to 150% R.C. safe overload);

Tool preparation: Suitable torque wrench (ensure thread fixing torque compliance), level (calibrate installation plane), cleaning tool (clean installation surface impurities).

2. Mechanical installation requirements

Installation plane: The support surface should be flat (flatness error ≤ 0.1mm/m), sturdy, and avoid affecting measurement accuracy due to deformation of the support surface;

Alignment requirements:

When installed vertically, the load should be applied along the axis direction of the sensor, and tilting is prohibited (deviation ≤ 0.5 °);

When installing horizontally (such as a belt scale), the sensor needs to be accurately aligned with the weighing frame to avoid lateral forces;

Load limit: Strictly control lateral force and torque to ≤ 10% R.C., and install guiding devices (such as locating pins) if necessary;

Fixed specifications:

Range (R.C.) Fixed thread specification Recommended torque (Nm) Prohibited behavior

Excessive tightening of M6 8 from 10kg to 50kg (to avoid deformation of the elastic body)

100kg-200kg M8 12, use a hammer to strike the sensor (damaged strain gauge)

500kg-1000kg M12 18 sensor in direct rigid contact with load (without buffering)

2000kg-5000kg M16 20 adjust the load direction after installation (generate lateral force)

3. Electrical connection specifications

Wiring method: Adopting a 4-wire system (red: excitation+, black: excitation -, green: signal+, white: signal -), some models support a 6-wire system (including compensation lines to improve long-distance transmission accuracy);

Cable requirements:

Use shielded cables (recommended cross-sectional area 0.25mm ² -0.5mm ²), with a cable length of ≤ 30m (if exceeding, a 6-wire system or signal amplifier is required);

Single end grounding of cable shielding layer (only grounded at the weighing instrument end to avoid the formation of grounding circulation);

Joint protection: IP67 waterproof joint is used, and the sealing nut needs to be tightened tightly after connection to prevent liquid infiltration;

Insulation requirement: Before wiring, a multimeter should be used to check the insulation resistance of the sensor (≥ 5000M Ω) to avoid signal interference caused by poor insulation.

Calibration and maintenance process

1. Calibration specifications

Calibration standard: Must comply with OIML R60 C3 level requirements, with calibration equipment accuracy ≥ 1/3 C3 level (such as standard weights, SIWAREX calibration tools);

Calibration conditions:

After the installation of the sensor is completed, let it stand for 24 hours (to ensure the release of elastic stress);

The ambient temperature remains stable at * * -10 ℃~+40 ℃ * * (within the temperature compensation range);

No vibration or airflow interference;

Calibration steps:

No load calibration: Ensure that the sensor is unloaded, perform "zero calibration" through the weighing instrument, and clear zero drift;

Loading calibration: Load standard weights in the order of 25% R.C., 50% R.C., 75% R.C., and 100% R.C., and record the instrument display value;

Error correction: If the displayed value deviates from the standard weight by more than ± 0.02% R.O., adjust the sensitivity through instrument parameters and repeat loading until the error is compliant;

Calibration records: Save calibration data (date, equipment, personnel, error values), and calibration certificates must comply with NIST traceability requirements.

2. Daily maintenance

Cleaning requirements: Clean the sensor surface every 3 months (using a dry soft cloth and avoiding the use of corrosive cleaning agents) to prevent dust and liquid accumulation from affecting the protective performance;

Status check:

Monthly inspection of mechanical connections (whether threads are loose and joints are sealed);

Check electrical connections (insulation resistance, cable shielding layer grounding) every 6 months;

Calibration cycle: Under normal usage scenarios, calibration should be conducted every 12 months. If used for trade settlement or harsh environments (such as vibration and high temperature), it should be shortened to 6 months;

Fault handling: When weighing data drift and accuracy decrease are found, priority should be given to checking the installation status (whether there is lateral force or deformation of the support surface), and then recalibration should be carried out. If there are still abnormalities, Siemens maintenance should be contacted.

Safety and Compliance

1. Safety regulations

Overloading is prohibited (long-term load ≤ 100% R.C., short-term impact ≤ 150% R.C.);

Sensors are precision equipment and should not be disassembled, knocked or welded, as this may cause permanent damage;

Explosion proof scenarios require the use of ATEX certified models, and conventional models are prohibited from being used in explosion-proof areas (such as chemical workshops).

2. Compliance certification

Compliant with EN 61298-2 (Safety Requirements for Industrial Weighing Equipment) and IEC 61298-2 (International Standard);

Having CE certification (EU market access) and optional ATEX certification (for use in explosion-proof areas);

The weighing accuracy meets OIML R60 C3 level and can be used in trade settlement scenarios (with compliance instruments required).

Application scenarios and adaptive instruments

1. Typical application scenarios

Application type, specific scenario, recommended range, protection level requirements

Belt scale weighing industrial belt conveyor (such as coal and ore transportation) 500kg-5000kg IP67

Weighing of chemical raw material tanks and food ingredient hoppers 100kg-5000kg IP67/IP68 (wet)

Automatic packaging machine for packaging equipment (such as flour and feed packaging) 10kg-200kg IP67

Industrial batching system multi-component mixed batching (such as concrete, paint) 50kg-1000kg IP67

2. Adapt to Siemens instruments

SIWAREX M: Modular weighing instrument, compatible with single/multi-sensor systems, supports PROFIBUS communication;

SIWAREX FTC: Compact instrument suitable for weighing belt scales and material tanks, with automatic calibration function;

SIWAREX U: Universal instrument, supporting 4-20mA analog output, suitable for small and medium-sized weighing systems.