The Electrical Building Design Show, presented by David Robison, and co-host Mark Robison, P.E. looks at the sometimes-misunderstood topic of overload protection. While their purpose is similar, overload protection and circuit breakers serve different functions, and understanding these differences is important for electrical designers.
Overload protection is designed to safeguard motors and their loads from minor, yet potentially damaging, increases in current. Unlike circuit breakers, which protect against large overloads and short circuits, overload protection devices are more sensitive. They are tuned to detect slight overcurrent situations that could damage the motor over time, something breakers might not catch since they are often oversized to handle the motor inrush current.
Highlights presented in this episode include:
- Why Electrical Engineers Should Care: Fully understanding the specified equipment ensures the motor design will be properly protected.
- How Overload Protection Works: Simply put, bimetallic elements within the motor heat up to a point where they change shape and break contact at unsafe current levels.
- How Overloads Are Wired: Overloads are wired in series with the main conductors of the motor, and have low resistance, so they do not affect performance under normal conditions.
- And more…
The Bottom Line:
Overload protection is a critical component of motor safety. It protects motors from subtle overcurrent that circuit breakers might miss. For electrical designers, understanding how overload protection works and how to specify it properly is a crucial feature of the motor design.
We invite you to watch the video below, where David and Mark go into greater detail on overload protection. Keep watching future videos for more topics related to induction motors.
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