HOLT Electricians Practice Exam

What component's specifications are critical for determining overload protection device size for motors rated 1 horsepower or less?

1. Voltage rating

2. Service factor

3. Motor nameplate rating

4. Thermal protection rating

The correct answer is: Motor nameplate rating

The motor nameplate rating is crucial for determining the appropriate overload protection device size for motors rated 1 horsepower or less because it provides key information about the motor’s electrical characteristics, including its full-load current, voltage, frequency, and service factor. These specifications help ensure the protection device is accurately sized to prevent damage to the motor under overload conditions. The motor nameplate includes the motor's rated horsepower, which directly influences the required size of the overload protection device. If the overload protection is incorrectly sized, it may fail to trip during an overload condition, potentially damaging the motor, or it could trip too frequently under normal operating conditions, leading to unnecessary downtime. While voltage rating, service factor, and thermal protection rating are important components, they do not encompass the comprehensive electrical performance and operational characteristics that the nameplate rating provides. Consequently, understanding and applying the motor nameplate rating is essential for maintaining the efficiency and longevity of the motor within its specified operational parameters.