Transformer Types & Applications
- Electrical devices that convert AC voltage levels (high to low or low to high) using electromagnetic induction.
- Input and output are AC.
- Primary Coil/Winding: Input side wire wrapped around the core.
- Secondary Coil/Winding: Output side wire wrapped around the core.
- Core: Ferromagnetic material (e.g., iron) that conducts a magnetic field.
- Utilizes mutual inductance to induce AC voltage in the secondary coil from AC current in the primary coil.
- Core concentrates the magnetic field, improving energy transfer efficiency.
Mutual Inductance
- AC current in one coil induces AC voltage in a nearby coil due to the magnetic field.
Turns Ratio (TR)
- Ratio of the number of turns in the primary coil Np to the number of turns in the secondary coil Ns.
- TR = \frac{Np}{Ns}
- Vs = \frac{Vp}{TR}, where:
- V_s = secondary voltage (Volts)
- V_p = primary voltage (Volts)
- TR = turns ratio
- TR = \frac{Vp}{Vs}
- TR = \frac{Np}{Ns}
- \frac{Vp}{Vs} = \frac{Np}{Ns} = \frac{Is}{Ip}
- Ideally, input power equals output power, but in practice, power loss occurs:
- P{in} = P{out} + P_{loss}
- Power loss is converted to heat; efficiency can be calculated.
- Isolation Transformer
- Autotransformer
- Control Transformer
- Primary and secondary are physically isolated (no electrical connection).
Advantages
- Reduces or eliminates voltage spikes in the secondary.
- Protects secondary load from primary shorts.
- Uses a single coil for both primary and secondary.
- Taps on the coil provide different voltage ratios.
- Reduces main power line voltage to a lower voltage for machine control systems.
- Common type has two primary coils (H1H2 and H3H4) and one secondary coil (X1X2).