Non-Contact Optical Fluid Level Detection for Stationary Batteries
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Solution Overview
Problem
Existing methods for monitoring the electrolyte fluid level in stationary batteries, such as those used in UPS systems, are unreliable, invasive, or cost-prohibitive due to the acidic and corrosive nature of the electrolyte, and require human intervention, which is not feasible in remote locations, especially when the container must remain sealed for safety and maintenance.
Innovation Solution
A non-contact optical fluid level detector system using light emitters and optical detectors positioned on the outside surface of the container, which emits light and measures reflectance to determine if the fluid level has dropped below a threshold, allowing for remote monitoring and alarm generation without direct contact with the fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If capacitive or sonic techniques are used to measure fluid level, then measurement capability is provided, but reliability deteriorates due to fluid properties (low dielectric value, surface tension, viscosity, conductivity) and environmental factors (electrical noise, mechanical vibration)
Solution Approach 1:
The patent replaces capacitive and sonic measurement techniques with an optical measurement system. Light emitters and detectors are used to measure fluid level through optical properties (light absorption, reflection, refraction) rather than electrical or acoustic properties, thereby avoiding interference from electrical noise, mechanical vibration, and problematic fluid properties like low dielectric value and variable conductivity.
Solution Approach 2:
The patent changes the measurement parameter from electrical (capacitive) or acoustic (sonic) to optical. By using light wavelength, intensity, and propagation characteristics as the measurement parameter, the system achieves reliable fluid level detection that is insensitive to fluid properties such as dielectric value, surface tension, viscosity, and conductivity that plague other measurement methods.
2Measurement precision
If sensors are immersed in the fluid to measure level, then direct measurement is achieved, but the system becomes invasive and requires access to the inside of the container, which is not acceptable for sealed containers or obstructed access points
Solution Approach 1:
The patent introduces an intermediary medium (the container wall) through which optical measurements are transmitted. Light emitters and detectors are positioned outside the container, and light passes through the container wall to interact with the fluid. This intermediary approach enables non-invasive measurement while maintaining measurement precision, as the container wall does not significantly block or distort the optical path.
Solution Approach 2:
The patent extracts the measurement function from the fluid interior and relocates it to the exterior of the container. By positioning light emitters and detectors outside the container, the measurement capability is separated from the fluid environment, eliminating the need for invasive installation while preserving the ability to accurately measure fluid level through the container wall.
3Difficulty of detecting and measuring
If invasive sensors are used to detect fluid level, then measurement capability is provided, but the system becomes unacceptable due to the acidic and corrosive nature of the electrolyte fluid
Solution Approach 1:
The patent uses the container wall as an protective intermediary barrier between the measurement system and the corrosive electrolyte fluid. Light emitters and detectors are positioned outside the container, and the container wall serves as an optical window that protects the electronics from corrosion while allowing optical measurements to pass through. This eliminates exposure to harmful acidic and corrosive factors.
Solution Approach 2:
The patent replaces physical contact-based measurement (invasive sensors in the fluid) with non-contact optical measurement. By using light propagation through the container wall and fluid interface, the system achieves fluid level detection without any physical contact with the corrosive electrolyte, thereby eliminating corrosion as a harmful factor.
4Extent of automation
If remote monitoring is implemented, then human intervention is reduced, but existing methods require human personnel to check electrolyte level, which is not feasible in remote locations
Solution Approach 1:
The patent enables the battery system to self-monitor its own fluid level using external optical sensors. The light emitters and detectors continuously measure the fluid level through the container wall, and the system can autonomously detect when the fluid level drops below acceptable thresholds. This self-service capability eliminates the need for human personnel to physically inspect remote batteries, achieving true remote monitoring.
Solution Approach 2:
The patent replaces manual visual inspection with automated optical measurement. Light emitters and detectors automatically measure fluid level through the container wall, and electronic processing systems continuously monitor the measurements. This substitution of manual operations with automated optical-electronic systems enables remote monitoring without human intervention, making operation feasible in remote locations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate, remote, and cost-effective monitoring of electrolyte levels in stationary batteries, ensuring compliance with standards like NERC PRC-005 by preventing fluid level drops that could cause battery failure, without disrupting the battery's operation or requiring human presence.
Implementation Method 1
A non-contact optical fluid level detector system using light emitters and optical detectors positioned on the outside surface of the container, which emits light and measures reflectance to determine if the fluid level has dropped below a threshold
Data Source
AI summary
An apparatus for optically monitoring a fluid level of a container comprises a light emitter(s), a plurality of optical detectors, and a control system. The light emitter(s) is configured to emit light toward a target surface when positioned, at a fluid threshold level, on the outside of the container. Upper and lower optical detectors are configured to receive light reflected from the target surface when positioned on the outside of the container above and below the fluid threshold level. The control system detects, based on measured reflectance received by the upper and lower optical detector, whether the upper optical detector is above the fluid level and whether at least a portion of the lower optical detector is above the fluid level, and determines, based on these detections, whether the level of fluid within the container has dropped below the fluid threshold level.