Step-Up Transformer
A step-up transformer is a transformer that increases the voltage from the primary winding to the secondary winding. It is commonly used in power transmission systems where high voltage is required to reduce energy losses.
What Is a Step-Up Transformer?
In a step-up transformer, the number of turns in the secondary winding is greater than the number of turns in the primary winding.
- Secondary turns (Ns) > Primary turns (Np)
- Output voltage is higher than input voltage
- Current decreases as voltage increases
Working Principle
A step-up transformer operates on electromagnetic induction:
- AC voltage is applied to the primary winding
- A changing magnetic field is created in the core
- The magnetic field induces voltage in the secondary winding
- Higher number of turns produces higher voltage
Voltage Relationship
The voltage increase depends on the turns ratio:
Vs / Vp = Ns / Np
Example:
- Np = 100 turns
- Ns = 500 turns
- Vp = 10V
Vs = (500 / 100) × 10 = 50V
Current Relationship
In an ideal transformer, power remains constant:
Vp × Ip = Vs × Is
So:
- Voltage increases → Current decreases
- Power remains approximately the same
Applications
| Application | Purpose |
|---|---|
| Power Transmission | Increase voltage for long-distance transmission |
| Electrical Grids | Step up voltage at power stations |
| High Voltage Equipment | Provide required high voltage |
| Ignition Systems | Generate high voltage spark |
Advantages
- Reduces transmission losses
- Efficient energy transfer
- Essential for power distribution
- Simple and reliable design
Disadvantages
- Requires good insulation for high voltage
- Higher voltage increases safety risks
- More turns increase size and cost
Real-Life Example
At a power station:
- Generator output: 11 kV
- Step-up transformer output: 220 kV or more
This allows electricity to travel long distances with minimal losses.
Key Points
- Step-up transformers increase voltage.
- Secondary winding has more turns than primary.
- Current decreases as voltage increases.
- Used in power transmission systems.
- Based on electromagnetic induction.