Monitoring flood levels in underground electrical substations is a critical task for maintaining the integrity of urban power infrastructure, especially in areas prone to storm surges or water main failures. The following application story details a solution involving a high-performance submersible level transmitter designed to withstand the harsh conditions of these environments while providing secondary temperature monitoring.
- Substation Flood Monitoring: Real-time depth tracking in underground electrical vaults.
- Media Versatility: Robust sensing of clean water, silt-laden runoff, and insulating oils.
- Safety Compliance: Intrinsically safe design (Ex ia) for hazardous electrical environments.
- Integrated Sensing: Dual-purpose measurement of liquid level and ambient temperature.
An electrical utility operator required a specialized depth monitoring solution for underground substations prone to flooding from heavy rainfall or local pipe bursts. These installations present a challenging environment where the media is rarely pure water; the sensors must reliably detect and measure a mixture of clean water, muddy runoff containing abrasive silt, and potentially leaked insulating oils from electrical equipment. The application demanded a continuous level measurement range up to 15 meters, requiring a sensor with high ingress protection and the ability to operate across a broad temperature spectrum from 10 to 60°C. Furthermore, because these substations are classified as hazardous areas, the instrumentation had to meet strict intrinsic safety standards to prevent ignition in the presence of potentially flammable gases or dust.
The solution provided utilizes the LMK 382, a stainless steel probe specifically engineered for wastewater and higher viscosity media. At the core of this transmitter is a robust capacitive ceramic sensor, which is highly resistant to overpressure and chemical attack, making it ideal for the unpredictable fluid compositions found in subterranean vaults. The Al2O3 99.9% ceramic diaphragm is particularly effective in “pasty” or viscous media where traditional metallic diaphragms might suffer from fatigue or clogging. For this specific deployment, the probe was configured with an intrinsically safe (Ex ia) output, ensuring compliance with gas and dust explosion protection requirements essential for utility infrastructure.
Beyond level measurement, the configuration addresses the user’s need for environmental monitoring by incorporating an integrated Pt100 temperature element. This 3-wire resistance thermometer allows the operator to track ambient thermal conditions within the vault simultaneously with water depth, utilizing a single penetration and cable run. To ensure long-term survival in the presence of oils and varied temperatures, the probe features a TPE-U cable sheath, which offers superior durability and a temperature rating up to 125°C. The high-accuracy 4-20mA signal remains stable over long cable runs, providing the resolution necessary for early flood detection and automated pump activation.
LMK 382 Submersible Flood Level Transmitter with PT100 Temperature Sensor
- Part No: 566-1601-1-C-E-1-42-3-020-013
- Pressure Range: 0 to 16 mH2O
- Housing Material: Stainless Steel 1.4404 (316L)
- Diaphragm Material: Ceramic Al2O3 99.9%
- Output Signal: Intrinsic safety 4-20 mA / 2-wire
- Media Exposed Seals: FKM
- Electrical Connection: TPE-U cable (red, Ø 9.0 mm)
- Accuracy: 0.35% FSO
- Cable Length: 20 Meters
- Special Version: Integrated Pt100 temperature sensor