1 - Insulation Resistance Test
- Used to measure the insulation resistance of the transformer components.
- Apply HV DC then measure resistance.
- Indicate the condition of the insulation.
2 - Turn ratio Test
- Used to measure the turns ratio of the transformer (Primary and Secondary Windings.
- Apply voltage on winding then measure the voltage induced in the other winding.
- Percentage between voltages is the turns ratio of the primary and secondary windings.
- Accurate test.
- East to perform.
3 - Winding Resistance Test
- Used to measure the resistance of the transformer windings (primary and secondary).
- Done using LV DC source + Multimeter.
4 - Polarity Test
- Conducted to verify the polarity of the transformer windings.
- Apply DC source to the primary then measure secondary voltage.
- Polarity of the windings determined based on the direction of the induced voltage in the secondary winding.
- Simple and quick.
- Prevent damage of the transformer during installation.
5 - Open Circuit Test
- Performed to determine:
No Load Losses.
Magnetizing Current.
- Keep the secondary open circuited then apply voltage on the primary winding, then measure the primary (current and voltage).
- Calculate (No-Load Losses & Magnetizing Current).
- Determine the equivalent circuit then calc Efficiency and Regulation.
6 - Short Circuit Test
- Performed to determine:
Full Load Current.
Transformer Impedance.
- Keep the secondary short circuited then apply voltage to the primary winding, then measure the primary (current and voltage).
- Calculate (Full-Load Current & Impedance).
- Determine Winding Resistance.
- Determine Leakage Inductance.
7 - Sweep Frequency Response Analysis (SFRA)
- Non-destructive test used to detect any changes in the transformer mechanical structure.
- It can detect Winding Deformation or Shorted-Turns.
- It makes comprehensive assessment of the transformer condition.