Themain transformerbackupprotection reports long-time action and alarm action ofcompound voltage blocking during operation.

The troubleshooting method is:

In general, operation is carried out onsite, direct shutdown of busbar on the medium voltageside ofmain transformer leads to adjacent multi-voltage locking contact of backup protection on medium voltage side, the backup protection on highvoltage side is blocked, and this is a normal situation.

Whether the polarity ofbusbar protection needs to be fixed? If it needs to be fixed, how to fix it?

The troubleshooting method is:

Thepolar ends ofCT in various branches must be consistent; in the device, theCT polarity ofbus couplershould be the same as that of branch on busbar II by default, and theCT polarity of section 1 and section 2 should be the same as theCT polarity of various branches. The bay ofbus coupler 1 should be fixed asL1, the bay of section 1 should be fixed asL23, and the bay of section 2 should be fixed asL24.

In busbar protection onsite, the branches of main transformers have fixed bays.

The troubleshooting method is:

The bays of main transformer branches are fixed as L2, L3, L14 and L15, corresponding to main transformers 1~4, respectively.

After the protection device has sent thetotal fault signal, the signal is reset automatically.

The troubleshooting method is:

According to the new regulations ofSouth Grid, the protection device needs toautomatically reset the signal after sending thetotal fault signal.

Selection ofsynchronization method

The troubleshooting method is:

Themeasuring and control device is equipped with different programs for different regions. In theSouth Grid, thesynchronization method ofmeasuring and control device is determined according to the setting values; in the State Grid, thesynchronization method ofmeasuring and control device is selected according to the remote control channel selected by background.