Pressure Transmitters, series EDA.370

-       Zero & Span Adjustment Function

-       High insulation grade, > 2000MΩ at 500 VDC

 

■ Supply Specifications

■ Pressure Ranges

● -1… 0 bar, from 0…1 to 0…1000 bar

 

■ Accuracy class

● 0.5% F.S [standard], 0.25% F.S, 0.1% F.S

 

■ Electrical connection

● mPm plug

● DIN plug according to DIN43650A

 

■ Analog signal output

● 4...20 mA, 2 wire-system [under construction]

● 0…10V, 3 wire-system

● 0…5V, 3 wire-system

● 1…5 V, 3 wire-system

 

■ Operating temperature ranges

● -20…+80 ℃ / standard

● -40…+125℃ / option

 

■ High Insulation: > 2000MΩ at 500 VDC

 

■    Zero & Span adjustment Function]

In a pressure transmitter, Zero and Span adjustment functions are essential calibration processes to accurately convert the measured physical pressure into a precise electrical signal (e.g., 4–20 mA). In industries where precision and safety are critical, this function is especially important.

 

1. Accurate Reference Point Setting (Zero Adjustment)

● Zero adjustment ensures that when no pressure is applied (0 bar), the output signal precisely matches the reference value (e.g., 4 mA).

● Sensor aging and deformation: Over time, the internal diaphragm (pressure-sensing element) may slightly deform or drift. Zero adjustment re-establishes the correct baseline.

● Installation environment effects: Depending on installation height or mounting angle, minor pressure offsets may occur. Zero adjustment compensates for these factors and defines them as true “zero.”

 

2. Optimization of Measurement Range (Span Adjustment)

● Span adjustment ensures that the maximum pressure (Full Scale) corresponds exactly to the maximum electrical output (e.g., 20 mA).

● System customization:
For a 4–20 mA output, the span equals 16 mA. After zero is set correctly, if the output at full scale reads 20.50 mA or 21.00 mA instead of 20.00 mA, the span is no longer exactly 16 mA. This deviation directly affects the transmitter’s accuracy and resolution. Span adjustment precisely sets the output to 20.00 mA, ensuring a true 16.00 mA span.

● Linearity assurance:
It guarantees that changes in input pressure and output current maintain a constant proportional relationship (linear response), allowing the control unit (ECU) to calculate accurate pressure values.

 

3. Practical Necessity of Zero & Span Adjustment in Systems

- Railway and Train Brake System Application

● Uniform braking force:
Each wagon in a train is equipped with pressure transmitters. Zero and Span must be aligned across all units to ensure consistent braking force throughout the entire train. Deviations may cause uneven braking, resulting in excessive or insufficient braking force in certain wagons.

● Maintenance efficiency:
When replacing a sensor, technicians can recalibrate Zero and Span on-site instead of modifying the entire system, enabling immediate and precise brake control.

 

Summary: “Adjusting the Scale of a Ruler”

● Zero: Aligning the starting point “0” on a ruler.
● Span: Ensuring the total length (e.g., 30 cm) is accurately represented according to the true measurement.

 

■    Application in Railway, High-Speed Train, and Metro Brake Operating Systems

In railway brake operating systems, the pressure transmitter is a critical component that precisely measures brake pressure and transmits it to the control system.

High insulation performance is required not primarily for thermal reasons, but for electrical safety and signal integrity.

 

1. Proximity to High-Voltage Systems

Electric trains operate with high-voltage power systems (e.g., 25,000 V AC or 1,500 V DC).

● Electromagnetic interference protection:
Strong electromagnetic fields generated by high-voltage lines or traction motors can interfere with sensor circuits. High insulation prevents external electrical noise from distorting pressure signals.

● Surge protection:
Unexpected surge voltages must be physically blocked from entering low-voltage control circuits (ECU) and sensors.

 

2. Safety Integrity of the Brake System

Braking systems are directly related to passenger safety.

● Prevention of malfunction:
Insufficient electrical insulation may cause leakage currents, resulting in incorrect pressure signals. This could lead to insufficient braking or sudden emergency braking.

● Ground fault prevention:
Train bodies are metallic and serve as grounding structures. If the sensor circuitry is not sufficiently insulated from the chassis, ground faults may occur, potentially shutting down the entire system.

 

3. Resistance to Harsh Operating Environments

Trains are exposed to severe vibration, dust, and moisture.

● Protection against contamination:
Metal particles from brake pads and moisture may create micro-conductive paths. High insulation design ensures reliable performance even under such harsh environmental conditions.

 

Conclusion

High insulation in brake system pressure transmitters is essential to protect precise braking control signals from high-voltage power systems and to ensure accurate braking performance under all operating conditions.

 

■ Optimized Development of Series EDA.370

 

The EDA.370 series has been optimized and developed for high precision, durability, and long-term maintenance requirements in demanding industrial environments.

 

It incorporates high insulation protection suitable for application in conventional trains, high-speed trains, and metro systems. Additionally, it has been developed for semiconductor manufacturing processes and marine industries.

The applied pressure transducer is based on a stainless steel 316L piezoresistive silicon pressure sensor. It integrates advanced electronic component manufacturing technologies and modern PCB chip design.

 

The electronic amplification section includes protection features such as Noise, Burst, Surge, and high insulation safeguards. Production is managed under strict process and quality control procedures to ensure stable analog signal output. Each unit undergoes precise calibration and 100% final inspection before shipment.

 

During development, performance comparisons were conducted against similar domestic and international products. Rigorous environmental testing was performed internally, resulting in superior quality performance of the EDA series.

 

EDA.370 is developed as a general industrial pressure transmitter suitable for manufacturing processes and industrial environments requiring precise control and instrumentation management.

 

Applications

● Railway brake operating systems
● Semiconductor manufacturing industry
● Automotive industry
● Hydraulic and pneumatic industry
● Oil refining and chemical industry
● Heavy industry and shipbuilding
● Pharmaceutical industry
● Food and beverage industry
● Power generation and nuclear industry
● Wastewater and water treatment industry

■ High Accuracy Options Available

The Series EDA.370 supports multiple accuracy classes according to customer requirements, as listed below:

● ≤ ±0.5% F.S [standard]

● ≤ ±0.25% F.S [option]

● ≤ ±0.1% F.S [option]

By referring to the EDA.370 data sheet, customers can select the required accuracy level and specifications to suit their specific application needs.