NABCEP Small Wind Installer 2 — Questions and Answers
Question 1: Which NEC article specifically governs the installation of small wind electric systems?
- Article 690
- Article 692
- Article 694 (Correct answer)
- Article 705
Correct answer: Article 694
NEC Article 694 covers small wind electric systems, addressing wiring methods, disconnecting means, grounding, and overcurrent protection.
Question 2: At what reference wind speed are small wind turbines typically rated for power output per IEC 61400-2 and AWEA standards?
- 8 mph (3.5 m/s)
- 11 mph (4.9 m/s)
- 24.6 mph (11 m/s) (Correct answer)
- 35 mph (15.6 m/s)
Correct answer: 24.6 mph (11 m/s)
Small wind turbines are rated at a reference wind speed of 11 m/s (approximately 24.6 mph) to provide a standardized basis for comparing turbine performance.
Question 3: What type of generator is most commonly used in small wind turbines?
- Synchronous generator directly coupled to the grid
- Permanent magnet alternator (Correct answer)
- Series-wound DC generator
- Squirrel-cage induction generator
Correct answer: Permanent magnet alternator
Permanent magnet alternators are preferred in small wind turbines because they operate efficiently at variable speeds and require no external field excitation.
Question 4: Which tower type is generally recommended for ease of maintenance on small wind installations?
- Fixed lattice tower
- Guyed lattice tower
- Tilt-up (hinged) monopole tower (Correct answer)
- Self-supporting monopole tower
Correct answer: Tilt-up (hinged) monopole tower
Tilt-up towers can be lowered to the ground using a gin pole and winch, allowing all maintenance to be performed at ground level without climbing.
Question 5: What is the purpose of a dump load (diversion load) in a battery-based small wind system?
- To start the turbine during low-wind conditions
- To dissipate excess energy when the battery bank is fully charged (Correct answer)
- To convert AC turbine output to DC for battery charging
- To measure and log system energy production
Correct answer: To dissipate excess energy when the battery bank is fully charged
A dump load absorbs surplus energy when batteries reach full state of charge, preventing overvoltage that would damage the battery bank and other components.
Question 6: Per NEC Article 694, at what percentage of maximum output current must conductors in small wind output circuits be sized?
- 100%
- 115%
- 125% (Correct answer)
- 150%
Correct answer: 125%
NEC Article 694 requires small wind output circuit conductors to be rated at 125% of maximum output current because wind generation is treated as a continuous load.
Question 7: What protection device is required on a grid-tied small wind system to prevent the turbine from energizing utility lines during a grid outage?
- Surge protection device (SPD)
- Anti-islanding protection (Correct answer)
- Ground fault protection device (GFPD)
- Arc fault circuit interrupter (AFCI)
Correct answer: Anti-islanding protection
Anti-islanding protection automatically disconnects the wind system from the grid during utility outages, protecting utility line workers from unexpected energization.
NABCEP Small Wind Installer 2
Which NEC article specifically governs the installation of small wind electric systems?