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Last updated: August 28, 2025

Overload Current Calculator: OLC Formula & Chart

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over load current calculator

Calculate overload current using I OL =I FL*SF, where I FL is full-load current and SF is the service factor or overload multiplier.

electrical overload calculator

In a calculation of overload current, a full-load current multiplied by service factor or overload percent addition is the right way.

Formula & Table Summary:

Formulas

  • Using SF: \( I_{OL} = I_{FL} \times SF \)
  • Using %OL: \( I_{OL} = I_{FL} \times (1 + \frac{\%OL}{100}) \)

overload protection current

The Overload Current Calculator determines the overload current limit to which overload protection trips,
IOL = IFL x SF or
IOL = IFL (1 + %OL/100).

overload trip setting calculator

IFL (A)SF%OLCalculationIOL (A)
10.01.1010 × 1.1011.0
12.51.1512.5 × 1.1514.375
15.020%15 × 1.2018.0
8.025%8 × 1.2510.0
20.01.2520 × 1.2525.0

Frequently Asked Questions - over load current calculator:

How do you calculate overload current?

Multiply full-load current by service factor or by (1 + overload%/100).

What is full-load current?

The current drawn by a motor or device at its rated load and voltage.

What is service factor in motors?

A multiplier indicating how much over the rated load a motor can operate without damage.

What is a typical motor service factor?

Common values range from 1.0 to 1.25.

How do you set overload protection?

Set it slightly above full-load current, based on SF or manufacturer data.

What happens if overload setting is too high?

The device may not trip in time, risking overheating and damage.

What happens if overload setting is too low?

Nuisance tripping may occur during normal operation.

Is overload current the same as short-circuit current?

No, overload is sustained overcurrent; short-circuit is a fault current many times higher.

Can overload current damage motors?

Yes, sustained overload causes overheating and insulation breakdown.

What devices protect against overloads?

Thermal overload relays, circuit breakers, and fuses.

Rojony Khatun

Rojony Khatun

CalculatorToolsProject

Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.