Question 518Electricity & Electronics - QMED

The correct answer is A) frequency meter. The RPM of an AC generator is indirectly measured through the frequency of the generated voltage. When a generator is operating singly, without any other generators connected to the bus, the frequency meter on the switchboard will indicate the generator's frequency, which is directly proportional to its RPM. This allows the operator to monitor and adjust the generator's speed to maintain the desired frequency and voltage. The other options are incorrect because: a voltmeter measures voltage, not RPM or frequency; a synchroscope is used to synchronize generators, not measure individual generator RPM; and synchronizing lamps are used to visually indicate when generators are in sync, not to measure RPM.