Comparison of Ceramic Electrical Insulators and Glass Electrical Insulators

The advantages and disadvantages of ceramic electrical insulators and glass electrical insulators can be introduced from the following six aspects:

1. Mechanical strength 

Through the electromechanical function comparison test of these two kinds of insulators with different working years on the line, it is found that the test value of some ceramic electrical insulators after 15-20 years of operation has been lower than the factory test specification value, and its failure rate increased with the increase in working years. The stability and dispersion of glass is better than porcelain. The results of high-frequency oscillation fatigue tests on two kinds of insulators show that the electromechanical strength of glass electrical insulators decreases significantly after high-frequency oscillation.

2. Anti-aging function

Ceramic electrical insulators have a service life of nearly one hundred years, and their anti-aging ability is strong. Within a period of time after being put into operation, a small number of degraded insulators can be replaced by detection means. But with the increase of working hours, its aging will become more serious. The toughened surface of the glass constitutes a compressive stress. If there are micro-cracks on its surface, the solid stress effect will compress the micro-cracks without expanding. The electrical strength of glass generally remains unchanged during the entire working period, and its aging process is much slower than that of porcelain.

3. Electrical function

Under the effect of standard shock wave, the electrical breakdown strength of glass medium is 1350～1700 kV/cm, which is about 3.8 times that of porcelain. The shock wave with a steep wave head has been used for many tests at home and abroad. The results are atmospheric flashover, and the glass body is not broken down. Operating experience also proves that glass electrical insulators will not be broken down by lightning.

4. Voltage distribution

Due to the large dielectric constant of the glass, the glass electrical insulator has a larger main capacitance, and the voltage distribution in the string is more uniform. The voltage of the glass insulator string is lower than that of the porcelain, and then the radio disturbance and corona loss are reduced. Hence the service life of  glass electrical insulators is extended and it also improves the flashover voltage of the insulators in series.

5. Scale and weight

Because the core rod has high tensile strength, the composite insulator can be made very light, which is only 1/10 of the weight of the porcelain insulator string. Since the dielectric constant of glass is 7-8, it is larger than the dielectric constant of porcelain(6-6.5). In the case of the same mechanical strength and breakdown voltage, its thickness is small, so glass electrical insulators are lighter than ceramic electrical insulators.

6. Later protection problem

The ceramic electrical insulator works reliably, but there are zero value detection problems and poor anti-fouling function. The glass electrical insulator has outstanding effect and convenient work protection.