USCG Exam PracticeSwitchboards and distribution systems
An AC emergency switchboard serves an emergency generator that uses a conventional field rheostat excitation system rather than a variable voltage or rotary amplifier exciter controlled by a voltage regulator acting on the exciter field. Under 46 CFR §111.30-29, which set of additional components is required at 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. A frequency meter, an exciter field rheostat, and a voltage regulator cut-out switch
- D. A ground detection system, an ammeter selector switch, and a voltmeter selector switch
Why B is correct
46 CFR §111.30-29(e) requires that when an emergency generator is not excited from a variable voltage or rotary amplifier exciter controlled by a voltage regulator acting on the exciter field, the emergency switchboard must additionally have a generator field rheostat, a double pole field switch, discharge clips, and a discharge resistor. The items in options C and D are required for all AC emergency switchboards under §111.30-29(f) regardless of exciter type.
Cited:46 CFR §111.30-29