Matters needing attention of voltage transformer. 
1. Before the voltage transformer is put into operation, it shall be tested and inspected according to the prescribed project. 
For example, polarity measurement, connection group, insulation shaking, nuclear phase sequence, etc. 
2. The wiring of the voltage transformer should ensure its correctness. 
The primary winding should be connected in parallel with the circuit under test, and the secondary winding should be connected in parallel with the voltage coil of the connected measuring instrument, relay protection device or automatic device, and pay attention to the correctness of polarity. 
3. The load capacity connected to the secondary side of the voltage transformer should be appropriate, and the load connected to the secondary side of the voltage transformer should not exceed its rated capacity, otherwise it will increase the error of the transformer and it is difficult to achieve the correctness of the measurement. 
4. Short circuit is not allowed on the secondary side of the voltage transformer. 
Because the impedance of the voltage transformer is very small, if the secondary circuit is short-circuited, there will be a large current, damage the secondary equipment, and even endanger personal safety. 
The voltage transformer can install a fuse on the secondary side to protect it from the damage of the secondary side short circuit. 
Where possible, fuses should also be installed on the primary side to protect the high-voltage power grid from the transformer high-voltage winding or lead failure. 
5. In order to ensure the safety of people when they come into contact with measuring instruments and relays, the secondary winding of the voltage transformer must be grounded a little. 
Because after grounding, when the insulation between the primary and secondary windings is damaged, it can prevent the high voltage of the instrument and relay from endangering personal safety. 
6. Short circuit is absolutely not allowed on the secondary side of the voltage transformer.