Which measurement confirms that the generator is producing the correct frequency for grid synchronization?

• A. The frequency of the generator output matches the grid frequency within tolerance
• B. The output voltage magnitude equals the grid voltage
• C. The phase angle between lines is zero
• D. The current equals rated value

Answer: (A)

Synchronizing with the grid relies on matching frequencies. When the generator’s output frequency is the same as the grid frequency within the allowed tolerance, the generator can lock in with the network and share load smoothly, avoiding torque pulsations and unstable circulating power. If the frequencies don’t match, power flow becomes erratic and can lead to instability or protective trips.

Voltage magnitude and phase alignment matter, but they don’t by themselves prove proper frequency. The exact phase angle should be kept small at the moment of connection, but it isn’t a direct measure of frequency. Current level reflects load and impedance, not whether the generator is operating at the grid frequency.