1. What is an Electric Motor Overload Calculator?

Definition: This calculator determines the overload current of an electric motor based on its full load current and service factor.

Purpose: It helps electrical engineers and technicians properly size motor protection devices and ensure safe operation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I_{ol} \) — Overload current (amps)
• \( I_{fl} \) — Full load current (amps)
• \( SF \) — Service factor (typically 1.15-1.25)

Explanation: The full load current is multiplied by the service factor to determine the current at which overload protection should activate.

3. Importance of Overload Calculation

Details: Proper overload current calculation prevents motor damage from excessive current while allowing normal operational variations.

4. Using the Calculator

Tips: Enter the motor's full load current (from nameplate) and service factor (default 1.15). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical service factor?
A: Most motors have a service factor between 1.15 and 1.25, with 1.15 being common for general purpose motors.

Q2: Where do I find the full load current?
A: Check the motor nameplate or manufacturer specifications. It's usually listed as "FLA" (Full Load Amps).

Q3: When would I use a higher service factor?
A: For applications with variable loads or where occasional overload conditions are expected.

Q4: How does this relate to circuit breaker sizing?
A: The calculated overload current helps determine appropriate thermal protection settings, not instantaneous trip settings.

Q5: What about motors with no service factor?
A: Motors with no service factor (SF=1.0) should not be operated above their rated full load current.