Motor Overload Size Calculator

Inputs

View results
Use motor nameplate FLA or the current basis required by the project.
A
Entered multiplier applied to FLA. The default is a common screening value, not a universal rule.
%
Dial setting or selected relay/heater current to compare with the target.
A
Optional measured or expected running current for headroom against the selected setting.
A

Results

Default result
Edit inputs
Target overload setting (I_OL)
16.1 A
Pass

Nameplate FLA multiplied by the entered overload multiplier.

Also computed

Selected setting vs target (I_sel/I_OL) Pass 99.38 %

Selected setting divided by the calculated target setting.

Selected setting deviation (I_sel - I_OL) Pass −0.1 A

Selected setting is below the calculated target.

Running current vs setting (I_run/I_sel) Pass 75 %

Measured running current divided by the selected overload setting.

Running current margin (I_sel - I_run) Pass 4 A

Positive headroom between running current and selected setting.

Motor load vs FLA (I_run/FLA) 85.71 %

Measured running current divided by nameplate FLA.

Overload allowance above FLA (I_OL - FLA) 2.1 A

Target overload setting minus nameplate FLA.

Motor overload preview SELECTED VS TARGET RUNNING CURRENT VS SETTING 16.1 A target 4 A running-current margin
Method notes 2 notes
  • This page is a user-entered motor-overload setting screen, not an NEC table lookup or manufacturer heater chart.
  • Final motor protection depends on the motor nameplate, thermal unit or relay manufacturer instructions, starter/VFD behavior, duty cycle, branch-circuit protection and the adopted local code edition.

Powered by MachineCalcs ↗