In a motor circuit, when does a branch circuit draw peak current?

In a motor circuit, when does a branch circuit draw peak current?

• A. Immediately after starting
• B. When running at rated speed
• C. During steady state operation
• D. When turning off

Answer: (A)

In a motor circuit, peak current occurs immediately after starting the motor. This is because, at startup, the motor is initially at rest, and when power is applied, the motor must overcome inertia and start turning. During this period, the current drawn can be significantly higher than the running current, often referred to as inrush current or starting current. This high initial current is primarily due to the fact that the motor experiences a low impedance while stationary, resulting in a surge of current until the motor accelerates and reaches its rated speed. Once the motor is running at its rated speed, the current decreases to a stable, lower value needed to maintain operation under normal loads. Thus, the moment of starting the motor is crucial as it demands the maximum current draw, which is why the peak occurs at that time.

In a motor circuit, peak current occurs immediately after starting the motor. This is because, at startup, the motor is initially at rest, and when power is applied, the motor must overcome inertia and start turning. During this period, the current drawn can be significantly higher than the running current, often referred to as inrush current or starting current.

This high initial current is primarily due to the fact that the motor experiences a low impedance while stationary, resulting in a surge of current until the motor accelerates and reaches its rated speed. Once the motor is running at its rated speed, the current decreases to a stable, lower value needed to maintain operation under normal loads. Thus, the moment of starting the motor is crucial as it demands the maximum current draw, which is why the peak occurs at that time.