What Minimum Motor FLA Is Required for an ATS48 Soft Starter?
The ATS48 is designed to operate with a motor whose full load current (FLA) falls within 40% to 130% of the soft starter’s nominal current. This range is defined by the design limits of its current sensing and control system.
1. Current measurement operating range
The SCT (current transformers) and internal measurement circuits are engineered to provide accurate readings within a defined window.
- Below 0.4 × In, the measured signal becomes too small relative to the sensing range
2. Protection function validity
Motor protection functions (overload, stall, locked rotor) rely directly on current measurement.
- Below 40%, protection curves are no longer correctly scaled
- The starter may under-protect or fail to detect abnormal conditions
3. Risk of nuisance faults due to low current
When operating below the minimum threshold:
- The ATS48 may interpret the low current condition as an abnormal state
- This can lead to unexpected faults such as motor current-related trips or startup failures
- In some cases, the unit may fail to properly detect motor rotation or load conditions
If this article does not answer your question, check out our FAQ database that has answers to more commonly asked questions:
Frequently Asked Questions - Schneider Electric (se.com)
If this FAQ did not solve your issue, you can call us at 1-888-778-2733 Option 2 and then 4 or e-mail us at drive.products.support@se.com to create a case with our Technical Support Team.
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