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Measures to prevent ferromagnetic resonance
- Nov 29, 2017 -

Change the ratio of XC/XL, such as using a capacitive voltage transformer (CVT) or a certain size capacitor on the bus, so that XC/XL < 0.01 to avoid resonance.


The damping resistance of an appropriate numerical value is connected to the two ends of the voltage transformer open delta winding.


The capacitance current of 10kV and 35kV system in the power supply area is measured and the arc coil and the anti-harmonic device are installed in the substation with the capacitor current exceeding the standard.After the above improvements, it is possible to eliminate the failure of the fault caused by 10kV grounding system grounding fault.

But everything is not absolute, and needs daily maintenance and systematic understanding and maintenance.

Such as:

A 10kV aerial bare conductor is regularly checked for hidden dangers, which keeps it away from trees and buildings.

In the case of a line with possible grounding faults, an insulating sheath shall be installed, and an overhead insulated conductor shall be used instead of a bare conductor in urban or jungle intensive areas.

The root cause of ferromagnetic resonance is the iron core saturation, which is that the excitation characteristics of the voltage transformer are not good.

The nonlinear ferromagnetic characteristics of the voltage transformer are the fundamental cause of ferromagnetic resonance, and the saturation effect of ferromagnetic components also limits the amplitude of overvoltage.The circuit loss also causes the resonant overvoltage to be damped and limited.

Therefore, in the operation and maintenance, the transformer should be replaced with the original transformer.