Introduction
The Pressure Sensor Differential Amplifier System is designed to provide an accurate and stable (4–20mA) output based on the pressure present at the sensor inputs. This system is specifically used for the transformer oil circuit of 3-phase locomotives. It operates over a wide voltage range and incorporates active voltage-to-current circuitry to account for zero-bar pressure at the input of the pressure sensors. The system is built to withstand the harsh environment inside locomotives, including temperature extremes, vibrations, and shocks, and meets all relevant international railway standards.
System Overview
The differential amplifier includes robust power and signal circuitry, operating within a voltage range of +18V to +36V DC. It utilizes an active voltage-to-current circuit that ensures a 4mA offset current for zero bar pressure at the input. The system is highly reliable, low-maintenance, and designed for use in demanding locomotive environments, ensuring performance with no deviation across a wide temperature range.
Salient Features
| Feature | Description |
| Differential Amplifier | Industry-standard current loop for inputs and output, with built-in signal conditioning and filtering. |
| Shock and Vibration Resistance | Designed to withstand shocks, vibrations, and temperature extremes typically encountered in locomotives. |
| Standards Compliance | Complies with IEC 60571, IEC 61373, and IEC 61000, ensuring environmental and EMI/EMC compatibility. |
| Power Supply Protections | Reverse voltage, surge, over-current, and over-temperature protections built-in. |
| Connector Type | MIL-C-26482 circular connectors for high reliability. |
| Compatibility | Compatible with rail vehicle electronics. |
| Pressure Sensor Technology | Industry-proven piezo-resistive technology for accurate readings. |
| Cable Shielding | Shielded cables used for reduced noise and emissions. |
| Housing Material | Stainless steel housing for durability and corrosion resistance. |
| Reliability | Low thermal drift, low maintenance, and long-term reliability. |
Technical specification
| Parameter | Specification |
| Power Supply Voltage | 18V DC to 36V DC (Nominal 24V DC) |
| Protections | Transient, surge, reverse polarity |
| Current Consumption | Maximum 20mA |
| Signal Output | 4mA to 20mA |
| Characteristic Deviation | 0.25% FS |
| Zero Signal | 0.05% FS |
| TK Zero Signal | <0.02% FS/K |
| TK Output Range | <0.02% FS/K |
| Pressure Range of Sensors | 0-4 bar (relative), 0-2 bar (polarized) |
| Housing | Stainless Steel Enclosure |
| Cable | Radox GKW RW/EMV (electron beam irradiated), stranded tin-plated copper, 2*0.5mm² |
| Connectors | Signal: Amphenol 62IN-16F-14-5S, Power: Amphenol 62IN-16F-14-5S |
| Temperature Range | -25°C to +85°C |
| Media Temperature Range | -25°C to +125°C |
| Insulation | 500V AC for 1 minute between Housing and Electronics |
| Protection Class | IP53 |
| Climatic Conditions | As per IEC 60571 |
| EMI/EMC Compatibility | As per IEC 61000 Compatibility |
