Discussion on implementation of zero-sequence protection for transformer;

The end earth fault of big power source and long line makes zero-sequence protection appearing serious problem that protecting refused to move because the voltage of zero-sequence is low,and become a new difficult point that zero-sequence protection in practical application.

Study on the misoperation mechanism of zero sequence protection of grounding transformer on low resistance grounded 10 kV system;

It analysed influence and contermeasure of 10 kV neutral point earthing through minute resistance,and put forwards some ways of minute resistance value choice and zero sequence protection allocation.

The influence to the bus equivalent zero sequence impendance and zero sequence protection from the different neutral point earthing mode of the transformer s 110 kV side were specifically analyzed.

These problems caused by TA saturation,station transformer protection,excessive excitation inrush current and protection setting are analyzed in theory respectively,and the corresponding technical measures are proposed.

While equipment being changed, dispatching is special; testing the new equipment needs temporary protection setting and operation mode.

A discussion of protection setting of AT feeder line with short distance in electrification railway is given in this paper.

Calculating coverage of zero sequence current protection based on node impedance matrix;

The grounding current value,fault current feature of the small resistance grounding system and ranges of zero sequence current protection when grounding transformer is connected to different position are analyzed.

If the constant zero sequence impedance is used to set the current, the zero sequence current protection can not operate correctly.