A remote freshwater well monitoring system required a robust solution to track water levels over a 17-meter range in locations where traditional 2.4GHz wireless telemetry was insufficient due to extreme distances. The application demanded a fully battery-powered installation capable of years of operation without maintenance, utilizing cellular networks to bridge the gap between the remote wellhead and a central control system.
- High-durability ceramic piezo-resistive submersible sensors for long-term stability.
- Low-power cellular telemetry utilizing the MQTT protocol for efficient data transfer.
- Multi-year battery life supported by high-capacity 12Vdc lithium battery packs.
- Remote-to-local signal conversion for direct PLC integration at the destination.
The monitoring of freshwater wells in remote geographic locations, such as the expansive terrain of the Canadian wilderness, often presents significant logistical challenges for data acquisition. In this specific application, the wells are situated far from the processing infrastructure, rendering standard short-range wireless solutions ineffective. The requirement focuses on a measurement range of 0 to 17 meters at the wellhead, necessitates a hardware solution that can withstand permanent submersion, and must operate entirely on battery power due to a lack of reliable solar availability in high-latitude environments. Data transmission is required four times daily via a cellular provider, ensuring the system can maintain a battery life of at least two years to reduce the frequency of site visits.
The measurement solution utilizes the SLS Series submersible level sensor, which is engineered with a high-purity (Al2O3) piezo-resistive sensing element. This specific sensor technology is chosen for its exceptional corrosion resistance and long-term stability, housed within a 316 stainless steel body to ensure durability in freshwater environments. To maintain accuracy across varying atmospheric conditions, the sensor is equipped with a vented PUR cable, which allows the internal pressure reference to compensate for changes in barometric pressure. For this battery-dependent application, the sensor is configured with a raw millivolt output, a low-power alternative that avoids the current draw associated with traditional amplified signals, thereby extending the operational life of the primary battery source.
To facilitate the transmission of data over long distances, the sensor is integrated with the IoT-Gateway Series. This gateway serves as a cellular transmitter, utilizing Cat-M1 and 4G bands to send encrypted data strings via the MQTT protocol to a secure cloud-based platform. The gateway is designed to reside within a non-metallic enclosure at the wellhead to ensure optimal antenna performance for the cellular modem. When powered by a 30Ah 12Vdc lithium battery pack and programmed for a four-times-daily upload frequency, the system can achieve an operational lifespan exceeding two years. This configuration provides a highly reliable “sleep-and-wake” cycle that minimizes power consumption while ensuring consistent data logging of the well levels.
At the control destination, a second IoT-Gateway Series unit is deployed to act as a receiver. This unit is mains or auxiliary powered and is configured to download the latest well level data from the cloud platform. It then converts this digital information back into a local 4-20mA analog signal through its onboard output modules. This enables the remote well level data to be seamlessly integrated into a local PLC or SCADA system as if the sensor were hardwired directly to the controller. The complete end-to-end solution provides an accuracy class of 0.5% Full Scale, ensuring precise water resource management without the need for onsite power or expensive cabling infrastructure.
SLS-A Submersible Hydrostatic Level Sensor
- II-SLS-LC-AA-B020-BV-2001G-00
- Pressure Datum: Gauge
- Pressure Range: 0 – 20mW
- Output: mV/V / 4-wire
- Accuracy (Combined NL&H): 0.5% / FS (BFSL)
- Electrical Connection: Vented PUR Cable
- Housing Material: 316 Stainless Steel
- O Ring Seal: Viton
- Cable Length (enter in mtrs): 20 metre PUR
- Specials Code: No Special Requirements
IoT-Gateway Cellular Transmitter with mV Sensor Input
- Part No: IoT-GateWay-00
- Wireless Inputs: Up to 128 IWT Wireless transmitters
- Analogue Inputs: 4 x 4-20mA or 0-10Vdc
- Digital Inputs: 8 x Volt-free Digital Inputs
- Outputs: 4 x Relay contact outputs
- Communications Inputs: Acts as RS485 Modbus RTU master
- Display: 6 line LCD backlit display
- Cellular Connection: 2G/4G Transmit Bands MQTT protocol
- Power Supply: 12-36Vdc
IoT-Gateway Cellular Receiver with 4-20mA Output
- Part No: IoT-GateWay-06
- Wireless Inputs: Up to 128 IWT Wireless transmitters
- Analogue output: 4-20mA Analogue Output
- Digital Inputs: 8 x Volt-free Digital Inputs
- Outputs: 4 x Relay contact outputs
- Display: 6 line LCD backlit display
- Cellular Connection: 2G/4G Transmit Bands MQTT protocol
- Power Supply: 12-36Vdc