The oil level detection of transformer conservators is a technical problem in the power industry. If the oil level of a conservator is too high or too low, it is easy to cause accidents. When the oil level is too high, it may increase the oil pressure inside the transformer, and also cause oil spillage; When the oil level is too low, the transformer runs under low load or the temperature drops suddenly, which may cause less oil in the oil tank of the body, causing insulation failure; When the oil level is lower than the transformer cover, the winding and iron core will be exposed to the air, which may cause internal flashover. At the same time, the contact surface between oil and air will be increased, which will rapidly reduce the insulation performance of insulating oil. At present, manual on-site visual inspection is mainly used to check the oil level of a conservator. Glass tube-type oil level gauges and pointer-type oil level gauges are commonly used. The two oil level gauges have no remote signal transmission function and can only be observed visually on-site.
The connecting device principle adopted by the glass tube type oil level gauge makes the oil level in the conservator directly reflected on the glass tube, and the oil level height is clear at a glance. However, when used for a long time, the glass window is easily polluted and dirty, which makes it impossible to accurately judge the position of the oil and gas interface in the conservator through the window.
The pointer-type oil level gauge adopts the mechanical transmission principle. The change in oil level drives the pointer to rotate, and the pointer indirectly displays the oil level. When in use, the mechanical structure will lead to capsule damage and air leakage, as well as mechanical failure (transmission failure) leading to measurement errors.
The transformer conservator is closed. The maintenance and replacement of the existing oil level gauge require power failure, opening, and oil drainage, which is very complex. Therefore, it is necessary to design a non-contact oil level detector for the transformer conservator. Ultrasonic has good acoustic conductivity in solid, liquid, and gas, and can be used in strong magnetic interference environments; The interface reflection of ultrasonic waves between different mediums is the key to ultrasonic ranging. The ultrasonic sensor has a simple structure, low production cost, simple and reliable signal analysis, and processing, and is convenient for portable, integrated and real-time control. Therefore, according to the ultrasonic principle, a portable oil level detector of oil filling equipment is designed for the detection of transformer oil level, which can be used for a convenient, fast, and safe measurement.
The portable oil filling equipment oil level detector adopts the sonar ranging principle, transmits and receives sonar signals using a special probe attached outside the container wall, takes the special sonar wave processing technology as the system core, uses advanced high-speed signal processing technology, and uses the special algorithm of Shaanxi Acoustics to accurately calculate the oil level in the conservator.
When measuring the liquid level, the sonar wave signal is transmitted from the probe, and the echo signal is detected by the probe after being reflected back by the oil surface. The time t is calculated after being processed by a proprietary algorithm. The system calculates the oil level height according to the echo time and the sound velocity of the medium.
According to different requirements of portable oil filling equipment oil level detectors, Sino Electronics has designed two types of transformer-specific conservator level gauge products:
The portable conservator level gauge realizes the non-contact measurement of the oil level in the closed container without opening the tank. The sonar sensor can be used to measure directly below the outer wall of the conservator, which is convenient, fast, safe and reliable.