KONGSBERG GT300 pressure transmitter

Industrial application and technical advantages of KONGSBERG GT300 pressure transmitter

Pressure transmitters, as the "sensory nerves" of industrial control systems, are widely used in fields such as water conservancy and hydropower, shipbuilding, petrochemicals, and intelligent buildings. In harsh industrial environments, sensors not only face corrosion of the medium and pressure shocks, but also need to maintain long-term stable output under various temperature conditions. Although traditional diffusion silicon pressure transmitters have high sensitivity, they usually rely on filling liquid (silicone oil) to transmit pressure, which to some extent introduces measurement errors caused by thermal expansion or leakage.

As a globally renowned supplier of maritime and high-end industrial technology, Kongsberg Maritime's GT300 series pressure transmitters completely break free from the constraints of filling fluids by using dry ceramic capacitor/piezoresistive technology, achieving higher accuracy and environmental adaptability. This article will provide a detailed interpretation of the product from three dimensions: technical specifications, core design, and application scenarios.

Chapter 1: Product Overview and Application Positioning

1.1 Precise positioning of universal design

The GT300 pressure transmitter is defined as a general purpose transmitter, primarily designed for engine rooms, hydraulic stations, and similar industrial applications. It offers two forms of gauge pressure and sealed gauge pressure, covering a wide range of needs from micro pressure to high pressure.

1.2 Range and Output

This series supports a pressure range of up to 100 bar and adopts the industry standard 2-wire connection method, with output signals ranging from 4 to 20mA analog. This signal system has strong anti-interference ability and is suitable for long-distance transmission, making it a classic choice for industrial sites. Its nominal power supply value is 24 VDC, allowing for fluctuations within a wide voltage range of 12 to 32 VDC, greatly facilitating compatibility with different ship or factory power supply systems.

Chapter 2: Core Technology Innovation: Dry Ceramic Sensors

The most significant technical feature of the GT300 is its pressure sensitive element - a dry measurement unit made of 96% alumina (Al ₂ O3) ceramic.

2.1 Material advantage: 96% alumina ceramic

Alumina ceramics are widely recognized as highly elastic, corrosion-resistant, and wear-resistant materials. The GT300 uses 96% pure ceramic film, which has extremely high chemical inertness and can withstand the corrosion of most chemical media. This means that the measured process medium can directly contact the measuring diaphragm, without the need to transmit pressure through stainless steel isolation diaphragm and intermediate filling liquid (such as silicone oil) like traditional sensors.

2.2 Technical differentiation between wet and dry methods

In traditional "wet" sensors, the filling fluid is both a pressure transmission medium and a potential source of error. When the ambient temperature changes, the thermal expansion and contraction of the filling liquid will cause a volume change, thereby introducing temperature drift errors. In addition, if the isolation membrane is damaged and the filling liquid leaks, it will cause the sensor to completely fail. The "dry" design of GT300 fundamentally eliminates these issues, which explains why it can surpass traditional analog sensors in temperature stability indicators.

2.3 Signal Conversion and Digital Compensation

The internal core of GT300 is a rigid structure composed of ceramic membrane and insulating substrate. Strain gauges connected in the form of Wheatstone bridges are integrated on the membrane. When pressure is applied, the small deformation of the diaphragm causes a change in the resistance value of the strain gauge, which is converted into an electrical signal.

The revolutionary breakthrough of GT300 lies in its digital compensation process:

Individualized calibration: Each sensor undergoes dual scanning of pressure and temperature during the manufacturing process.

Table lookup compensation: The collected data is digitized and stored in the built-in memory of the sensor, forming a unique 'Tabular'.

Real time calibration: During operation, the microprocessor combines real-time temperature and pressure signals to perform linearization and temperature compensation calculations based on this table.

This digital compensation technology based on the unique characteristics of each component enables the GT300 to achieve accuracy and stability far ahead of analog sensors in the compensation temperature range of 0 to 60 ° C, ultimately ensuring a full-scale output accuracy (FRO) of 0.5%.

Chapter 3: Mechanical Structure and Material Technology

3.1 Shell and Protection

The main structure of GT300 is made of AISI 316L stainless steel. 316L is a low-carbon, molybdenum containing austenitic stainless steel with excellent resistance to intergranular corrosion, especially chloride ion corrosion, making it very suitable for ships and offshore environments. Its protection level reaches IP56, which means it can prevent dust (dust level 5, no harmful deposits) and strong water spray, sufficient to cope with the flushing and humid environment inside the cabin.

3.2 Pressure and Electrical Interface

Pressure interface: The pressure connection located at the lower end of the transmitter complies with the ISO228 standard and mainly provides two specifications of cylindrical threads, G1/2A and G1/4A. These threads are usually sealed with sealing gaskets (such as Viton seals provided with the goods).

Electrical interface: The upper end adopts a connector that complies with DIN 175301-803 standard. This type of connector is commonly known as the "Hirschman connector" or "square plug" in the industrial field, with convenient and reliable wiring. Users can choose the appropriate cable gland based on the outer diameter of the cable, such as M16 or M20 specifications.

Chapter 4: Electrical Characteristics and Installation Specifications

4.1 Power Supply and Load Capacity

The electrical design of GT300 follows the principle of two-wire circuit power supply. The load resistance capability depends on the magnitude of the supply voltage. As shown in Figure 1 (original Fig.1 in the manual), the allowable load resistance is proportional to the power supply voltage. For example, when powered by 24V, it can drive loads up to about 600 Ω (excluding the minimum operating voltage of the transmitter itself), making it easy to work with PLC analog input modules or digital display instruments.

4.2 Wiring Details

When wiring, attention must be paid to polarity and shielding layer handling:

Terminal definition: Terminal 1 is connected to the positive pole (+) of the power supply, and terminal 2 is connected to the negative pole (-) of the signal output.

Cable requirements: Copper screened cable with shielding layer must be used, and the cable cross-sectional area is recommended to be no less than 2 x 0.5 mm ².

Grounding principle: In order to prevent electromagnetic interference (EMI) from affecting the measurement signal, the shielding layer must be single ended grounded on the monitoring system side (i.e. PLC or control cabinet side).

4.3 Fault safety logic

GT300 has a fault self diagnosis function. When there is a malfunction inside the sensor (such as component damage or disconnection), the output current will drop below 3.6mA or rise above 22mA. This "transmitter fault current" mechanism helps the control system identify sensor abnormalities and avoid misoperations caused by incorrect readings.

Chapter 5: Installation Practice and Precautions

Although the GT300 is designed to be sturdy and durable, proper installation is a prerequisite for unleashing its performance.

5.1 Installation direction

The manufacturer recommends installing vertically. This is not only beneficial for mechanical stability, but also reduces zero offset caused by the self weight of the membrane or the deposition of small particles in the medium.

5.2 Installation method

Direct installation: It can be welded directly onto the base of the measuring point through bolts.

Remote installation: Introduce pressure into the transmitter through a pressure conduit. For steam or high-temperature media, the pressure pipe can also play a role in heat dissipation and buffering, preventing high temperatures from directly impacting the sensor electronic unit.

5.3 Environmental Requirements

Despite having IP56 protection, the electronic part of the sensor should be avoided from being exposed to severe thermal radiation or strong electromagnetic interference sources during long-term use. If the temperature of the measured medium changes dramatically, damping or buffering devices can be added within the allowable range of the process.

Chapter 6: Selection Guide and Order Code Interpretation

Understanding the ordering code of GT300 is crucial for proper procurement. According to the "Ordering key" on page four of the manual, we can deconstruct it as follows:

Model example: GT300 C 0 0 C G 1 0 G 0 E05 XXX

GT300: Basic series number.

Pressure Connection:

V=G1/2A, AISI 316L material, Viton seal.

B=G1/4A, AISI 316L material, Viton seal.

OUTPUT SIGNAL:

0 = 4-20mA， Second line system.

Application:

0=General/engine compartment.

Accuracy:

C=0.5% accuracy, temperature compensation range 0-60 ° C.

ZERO POINT:

G=4mA corresponds to atmospheric pressure (zero point of gauge pressure).

K=4mA corresponds to -1 bar gauge (for vacuum or negative pressure measurement).

RANGE AND OVERLOAD PRESSURE:

This is a combination code, for example, 10 corresponds to a range of 0-10 bar and overload of 20 bar; 60 corresponds to a range of 0-60bar, overload of 100bar, etc.

CABLE GLAND:

1=M16 (applicable for cable diameters of 3.5-8mm)

2=M16 * (applicable cable diameter 6-10mm)

3=M20 (applicable cable diameter 7-13mm)

CABLE (cable option):

E05=with 5-meter cable (EFTE oil resistant material)

E10=with 10 meter cable

XXX=Special Customization

Chapter 7: Performance Comparison and Industry Development Trends

7.1 Ceramic Sensor vs. Diffuse Silicon Sensor

In the field of industrial pressure measurement, diffusion silicon sensors and ceramic sensors are the two mainstream technologies. The diffusion silicon sensor has extremely high sensitivity and is suitable for micro pressure measurement, but its PN junction is easily affected in high temperature environments and must rely on a filling liquid isolation medium. Although ceramic sensors (such as those used in GT300) have slightly lower sensitivity than silicon, their characteristics of no hysteresis, overload resistance, and corrosion resistance make them have a longer service life and stability under harsh working conditions. The 0.5% accuracy of GT300 is considered excellent in the general industrial field, while its long-term drift is controlled at an extremely low level through digital compensation.

7.2 Overload resistance capability

Overload is the main cause of sensor damage. The elastic limit of ceramic materials is extremely high. When the pressure instantly exceeds the range or even reaches several times the overload, the ceramic diaphragm will adhere tightly to the substrate (bottom) instead of undergoing plastic deformation like metal diaphragms. Once the pressure returns to normal, the sensor immediately resumes operation with unchanged performance. The GT300 provides clear overload pressure indicators for different ranges, such as a 0.6bar range that can withstand an overload of 2bar, and a 10bar range that can withstand an overload of 20bar.

Chapter 8: Maintenance and Troubleshooting

In practical applications, GT300 may experience output abnormalities, which can usually be attributed to the following reasons:

Blockage of the pressure system: Sediments or crystals at the process connection block the pressure channel.

Wiring and grounding: The shielding layer is not properly grounded or the cable is laid in parallel with the power cable, which introduces interference.

Sealing failure: The aging or improper installation of Viton sealing rings leads to medium leakage.

Exceeding compensation temperature: Although the storage temperature range is wide, if electronic components work at 85 ° C or above for a long time, it will accelerate component aging.

It is recommended that users perform regular zero calibration (adjust under no pressure) and check whether the cable joints are loose or have water ingress.