Today I will introduce you the security requirements of quality control transformer.
1. Insulation resistance
The insulation resistance of the control transformer in the cold state should not be lower than 10 MΩ; the insulation resistance of the control transformer in the hot and damp state should not be lower than 2 MΩ.
2. Dielectric strength
The electrical insulation strength of the control transformer should be able to withstand the withstand voltage test of AC 50Hz, 2000V sinusoidal AC voltage, and no breakdown or flashover will occur for 1min.

3. Leakage current
The leakage current of the control transformer shall not exceed 3mA.
4. Temperature rise
The limit temperature rise of the coil of the control transformer (E-class insulation) shall not exceed 75K (resistance method); the limit temperature rise of the iron core (E-class insulation) shall not exceed 55K (semiconductor point thermometer method).
5. Grounding
The quality control transformer shall have a dedicated terminal for grounding and shall be marked with a grounding symbol.