Are all generators connected to a regional transmission network at the same angle of rotation (unison) at any given time?

Are all generators connected to a regional transmission network at the same angle of rotation (unison) at any given time?

• A. True
• B. False
• C. Sometimes
• D. Not specified

Answer: (A)

All generators on the same regional transmission network are tied to the same electrical bus and run at the same system frequency. Because they feed into that common bus, their terminal voltages must be in phase with each other. If any generator’s rotor angle were noticeably different, circulating currents would flow between machines and the system could become unstable. Governors and control systems continuously work to keep each generator’s rotor angle aligned with the bus, so in normal operation they are effectively in unison. Transient events can cause brief deviations, but the intention and design are for synchronized, in-step operation at any given time.

All generators on the same regional transmission network are tied to the same electrical bus and run at the same system frequency. Because they feed into that common bus, their terminal voltages must be in phase with each other. If any generator’s rotor angle were noticeably different, circulating currents would flow between machines and the system could become unstable. Governors and control systems continuously work to keep each generator’s rotor angle aligned with the bus, so in normal operation they are effectively in unison. Transient events can cause brief deviations, but the intention and design are for synchronized, in-step operation at any given time.