USCG Exam PracticeSwitchboards and distribution systems
An AC emergency switchboard serves a generator that is excited from a conventional separately-excited field (not a variable voltage or rotary amplifier exciter controlled by a voltage regulator acting on the exciter field). In addition to the standard metering and protection items, which set of additional equipment does 46 CFR §111.30-29 require on that switchboard?
- A. A synchroscope, a wattmeter, and a power-factor meter
- ✓ A generator field rheostat, a double pole field switch, discharge clips, and a discharge resistorCorrect
- C. An automatic bus transfer relay, a load shedding contactor, and a governor speed control
- D. A second voltmeter to display exciter output voltage and a separate exciter ammeter
Why B is correct
46 CFR §111.30-29(e) requires that when the emergency generator is not excited from a variable voltage or rotary amplifier exciter controlled by a voltage regulator unit acting on the exciter field, the emergency switchboard must have a generator field rheostat, a double pole field switch, discharge clips, and a discharge resistor. The other options list real switchboard instruments but are not the items specified under this subsection.
Cited:46 CFR §111.30-29