Understanding Transformer Ratings
When a transformer is rated for a specific voltage and frequency, it operates optimally under those conditions. The given transformer has a primary rating of 400V and a secondary rating of 230V, designed for a 50 Hz supply.
Supply Voltage for 25 Hz
If the low voltage winding (230V side) is connected to a 25 Hz supply, the transformer will not function correctly if the voltage is not adjusted. The voltage must be determined based on the frequency change.
Voltage and Frequency Relationship
- The voltage ratio of a transformer is directly proportional to the frequency.
- Reducing the frequency from 50 Hz to 25 Hz implies a need to decrease the voltage to maintain the same magnetic flux in the core.
Calculating the New Supply Voltage
- The voltage transformation ratio is given as:
V1 / V2 = f1 / f2
where V1 is the primary voltage, V2 is the secondary voltage, f1 is the original frequency, and f2 is the new frequency.
- Applying the values:
400V / V2 = 50 Hz / 25 Hz
V2 = 400V * (25 Hz / 50 Hz)
V2 = 200V
Conclusion
To connect the low voltage winding of the transformer to a 25 Hz supply, the voltage should be adjusted to 200V. This adjustment ensures the transformer operates safely without exceeding its magnetic flux limits.