# Why should Overload Relay settings be adjusted for High-Inertia Motors?

**URL:** <https://forumautomation.com/t/why-should-overload-relay-settings-be-adjusted-for-high-inertia-motors/14188>\
**Category:** Electrical\
**Tags:** motor-control\
**Created:** [June 10, 2026, 4:27am UTC](https://forumautomation.com/t/why-should-overload-relay-settings-be-adjusted-for-high-inertia-motors/14188 "2026-06-10T04:27:46Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![NicholasDeo](https://forumautomation.com/user_avatar/forumautomation.com/nicholasdeo/32/7665_2.png) [@NicholasDeo](https://forumautomation.com/u/NicholasDeo)\
**Post date:** [June 10, 2026, 4:27am UTC](https://forumautomation.com/t/why-should-overload-relay-settings-be-adjusted-for-high-inertia-motors/14188/1 "2026-06-10T04:27:46Z")

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## Why should Overload Relay settings be adjusted for High-Inertia Motors?

 ![5](https://cdn.forumautomation.com/original/2X/6/670b74af737663364e118580778f179b84876d8e.jpeg)

**Reference Image Provided by the Respondent**

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**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [June 10, 2026, 7:11am UTC](https://forumautomation.com/t/why-should-overload-relay-settings-be-adjusted-for-high-inertia-motors/14188/2 "2026-06-10T07:11:25Z")

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High-inertia **[motors](https://forumelectrical.com/fat-test-of-electric-motors/)** take a longer time to accelerate because of they drive heavy rotating loads such as

- Crushers,
- Fans,
- Centrifuges,
- Conveyors and
- Large pumps.

During starting the motor draws high current for an extended period.

If the overload relay setting is too low (or) the trip class is not suitable:

- The relay may trip during normal motor starting.
- Frequent nuisance tripping may occur.
- Motor startup becomes so unreliable.
- Production interruptions & equipment stress may increase.

Therefore **[overload relay](https://forumelectrical.com/what-is-an-overload-relay-function-types-uses/)** settings should be adjusted properly to allow the motor enough starting time while it still protecting it against overheating & overload conditions.

## Important Adjustments

Select the correct overload current setting based on the motor **[full-load current (FLC).](https://forumelectrical.com/full-load-current-turns-ratio-calculator-for-transformer/)**

Use a higher trip class (such as Class 20 / Class 30) for a long acceleration times.

Consider the motor starting characteristics & load inertia.

Ensure a proper thermal protection without any unnecessary trips.

## Common Applications of High-Inertia Motors

- Conveyor systems,
- Ball mills,
- Large blowers and fans,
- Crushers,
- Centrifugal machines and
- Heavy industrial pumps.