[Example 15-11 Generator and Motor]
    1. The stator windings of the generator and the motor can be carried out by the applied current method and the direct shutdown detection method, and the thermal spectrum recording and analysis are performed on all the winding joints. For example, 72 of the 75 measuring points of a hydro-generator stator winding are continuously distributed between 42.5-62.5 °C (Is=0.68 Ie at the time of detection), and the temperature of the two measuring points is high (72.5 °C). ), 1 away from the continuous zone (95.8 ° C). High is defined as a general defect; away from it is a major defect. For the disintegration of joints with major defects, it was found that 2 of the 6 weld heads had poor weld quality and the resistance was 18.4 times that of the normal weld head (see Figure 15-2).
    2. The maximum temperature rise of the tooth is measured by the infrared detector to 26.2K, and the maximum temperature difference of the tooth is 17.1K, which exceeds the requirements of 25K and 15K of the Pre-Regulation.
    3. The temperature of a brush of a generator is measured by an infrared camera. It is found that the temperature of one of the brushes is above 150 °C, exceeding the requirements of GB/T 7064 and GB 755 (the general temperature rise limit is 80K, temperature limit) When the temperature rises or the temperature does not exceed the limit value, the temperature distribution is not uniform, and the brush exceeding the average temperature rise of 30K should be regarded as unqualified). The reason is that the contact pressure is not properly adjusted.
[Example 15-2] Transformer
    1. The temperature of a main transformer was measured by an infrared camera. It was found that there was an abnormality in the general arm of the A phase. After checking, the cap screw was not tightened, thus avoiding an accident (see Figure 15-3).
    2. The main transformer of a 110kV substation is measured by an infrared thermometer. The temperature of the two phases of the outlet wall bushings A and B is normal (27 ° C), while the temperature of the C phase is as high as 170 ° C. It is found that the hidden dangers are eliminated in time.
    3. The B-phase low-voltage side lead connector of a distribution transformer is measured by an infrared thermometer to be 114 ° C, which is 24 times higher than the specified 90 ° C. It is checked that the joint is in poor contact.
[Example 15-3] Circuit breaker and disconnector
    1. A substation 6kV circuit breaker, when measuring temperature with an infrared thermometer, found that the temperature of the B-phase contact housing part is 45.8690, which is judged to be poor internal contact and monitor operation. After one week, the temperature of the part was measured again at 70.89 ° C, which was judged to be a severe overheating failure. Outage maintenance, measuring the contact resistance of the breaker contact is 8.09mΩ, while the normal is less than 90μΩ. After disintegration, it was found that the contact surface of the static contact seat was ablated, and the contact resistance after the treatment was reduced to 53 μΩ. The temperature of the portion was normal after the operation.
    2. A SW2-220II type circuit breaker in a substation, when measuring temperature with an infrared camera, found that the temperature of the upper cap of the A-phase south column was 87 °C, the temperature rise was 70 °C, and the normal temperature of this part was 19 °C. The operating current is only about 1/3 of the rated current. After disintegration inspection, the fracture contact resistance of the circuit breaker is 52 times that of the normal phase (normal phase is 126 μΩ), and the contact surface between the support seat and the electrical connection portion of the upper part of the static contact has been ablated.
    3. The high-voltage isolating switch of a substation is measured by an infrared camera. The temperature of the blade is 150 °C, which exceeds the maximum allowable temperature (see Figure 15-4).
[Example 15-5] Cable
    The temperature of the cable head of a 30kV outlet cable of a substation measured by an infrared thermometer is 125 °C. After the shutdown, it was found that the cable head had a discharge mark due to poor sealing, and the temperature was normal after re-making the cable head.
[Example 15-6] Voltage-induced device
    1. For a lightning arrester of a 220kV substation, the thermal field measured by the infrared camera is unevenly distributed, the central temperature is high, and the temperature at both ends is low, and the upper and lower are close respectively. °C, the middle is 7.06 °C. The live test current is 560μA, which is 5 times larger than the previous test value, and rises to 756μA one day later, so it determines the emergency shutdown test. The insulation resistance has been reduced to 15 MΩ, indicating that the arrester has been severely wet.
    2. The capacitance type voltage transformer of a 220kV substation is measured by infrared thermometer. It is found that the C-phase upper capacitor porcelain sleeve has local overheating, the hot spot temperature is 16 °C, and the ambient temperature is 2 °C. The power outage inspection found that tan δ had reached 6.45%, which was seriously exceeded. Disintegration revealed that the copper strip from the inner core to the lead end had broken and the insulating oil had been overheated and blackened.
Piezoelectric ceramic are a ferroelectric compound. This means, that the electro-mechanical conversion process for producing a motion is related a kind of self-enhancement process based on an internal reorganization of the material's structure. This self-enhancement process results in the higher piezoelectrical efficiency of PZT when compared to natural materials like quartz.
Piezoelectric ceramic are generally manufactured from PZT (Pb - lead, Zr - zirconium, Ti - titanium). The PZT- formulation can be varied with a variety of dopants allowing for a broad spectrum of material properties optimized for different application profiles.
Yuhai Company is able to manufacture piezoelectric ceramic elements in a wide range of shapes and sizes. piezoelectric discs, piezo rings, piezo plates, and piezo tubes (cylinders) is the main shapes Yuhai Company most frequently manufactures, we also have a great deal of experience manufacturing hemispheres, trapezoids and other customized shapes.
If the listed shapes and sizes was not the elements you are looking for, please contact us for more information. We can work with you to create the correct shape and size for you.Piezoelectric Elements,Piezo Ceramic Disc,Piezoelectric Ceramic Discs,Pzt Element
Zibo Yuhai Electronic Ceramic Co., Ltd. , https://www.yhpiezo.com