DLT200 Pressure Transmitter Troubleshooting Guide: Analysis of 5 Typical Issues with Diffused Silicon Hirschmann Sensors

As a core component in industrial automation control, the stable operation of the DLT200 pressure transmitter is directly related to production safety. This article focuses on common faults of diffused silicon Hirschmann pressure sensors, summarizing 5 typical problems and their solutions, covering key technical difficulties such as accuracy abnormalities and signal distortion, helping technicians quickly identify issues and ensure the reliable operation of flow control systems.

I. Abnormal Output Signal or No Signal

When the DLT200 pressure transmitter shows signal abnormalities, the first step is to check whether the power supply is stable（24VDC±10%）. Diffused silicon Hirschmann pressure sensors are sensitive to voltage fluctuations, and it is recommended to use an oscilloscope to detect whether the power ripple exceeds 50mV. Next, check the wiring terminals:

• Confirm whether the Hirschmann connector is oxidized（common in humid environments）
• Measure the loop resistance（normal value is 250Ω±5%）
• Check whether the shield wire grounding complies with the IEC 61000-4-4 standard

If the above checks are normal, the sensor core may be damaged. When the overload pressure of a diffused silicon piezoresistive sensor exceeds 150%FS, the Wheatstone bridge may break, and the sensor module needs to be replaced at this time.

II. Zero Drift and Failure of Temperature Compensation

The zero drift of DLT200 is usually manifested as:

1. Under no-load conditions, the output signal exceeds the range of 4mA±0.5%
2. For every 10℃ change in ambient temperature, the zero offset exceeds ±2%FS
3. After restart, the zero value does not return to its original position

Treatment methods include:

• Use a dedicated calibrator to perform zero reset（refer to the GB/T 34036-2017 standard）
• Check the resistance value of the NTC thermistor in the temperature compensation circuit（it should be 10kΩ±1% at 25℃）
• For equipment used long-term, it is recommended to replace it with a new sensor featuring laser-trimmed temperature compensation, such as the third-generation compensation technology used in the domestic level transmitter PT601S

III. Measurement Failure Caused by Medium Crystallization

In chemical, wastewater treatment, and similar scenarios, the 316L stainless steel diaphragm of DLT200 may block the isolation diaphragm due to medium crystallization. Typical manifestations are:

It is recommended to select models with anti-clogging design under conditions prone to crystallization, as their special diaphragm structure can effectively prevent crystal adhesion.

IV. Accuracy Degradation Caused by Mechanical Vibration

When the DLT200 is installed in vibrating environments such as water pumps and compressors, mechanical vibration above 20g may lead to:

• Fatigue fracture of the lead wires of the diffused silicon chip
• Loosening of solder joints in the signal conditioning circuit
• Seal ring failure causing medium penetration

Countermeasures include:

1. Install anti-vibration brackets（complying with the GB/T 2423.10-2019 standard）
2. Switch to armored cables（vibration resistance rating increased to 50g）
3. Select sensors with an all-welded structure, such as some new models using MEMS packaging technology

V. Lightning Damage and Electromagnetic Interference

Outdoor-installed DLT200 may suffer lightning damage, manifested as:

• Burn marks on the circuit board
• Insulation resistance＜1MΩ（normally it should be＞100MΩ）
• Output signal continuously at full scale

Preventive solutions:

1. Install a three-level lightning protection module（shock resistance 100g/11ms）
2. Use twisted-pair shielded cables for signal lines（AWG18 and above）
3. Prefer models with integrated lightning protection design, such as some products equipped with transient voltage suppression diode arrays

Technical Summary and System Optimization Recommendations

For key process control points, it is recommended to establish a preventive maintenance mechanism: perform sensor calibration once every 6 months（refer to the JJG 882-2019 regulation）, focusing on checking zero drift and linearity. During the selection stage, models with higher protection ratings（such as IP68）and a wider operating temperature range（-40～125℃）can be considered, for example, some new-generation products using ceramic piezoresistive technology, whose long-term stability can reach ±0.1%FS/year.

As a national high-tech enterprise, Xi'an Shenghongchuang Instrumentation Co., Ltd. has produced a diffused silicon Hirschmann pressure sensor series that has passed SIL2 certification, making it particularly suitable for harsh environments such as petroleum and chemical industries. If you need the complete technical manual or customized solutions for the DLT200 pressure transmitter, please contact our professional technical team.