Performing the Test and Using the Calculator

The Importance of Stator Core Loss Testing

When an electric motor undergoes repair or rewinding, one of the most critical yet sometimes overlooked procedures is the stator core loss test. This diagnostic test is essential for verifying the integrity of the stator's laminated core. Performing this test correctly can prevent catastrophic post-repair failures and ensure the motor operates at its designed efficiency.

The stator core loss test, often called a "loop test," involves wrapping a test winding through the stator bore and around the back iron. An AC voltage is applied to this test winding to excite the core to its normal operating magnetic flux density. By measuring the power required to do this (with no rotor present), we can determine the core loss.

The calculator below is a tool designed to simplify the calculations required for this test. By inputting the physical dimensions of the stator and the target test parameters, it helps you determine the necessary "volts per turn" and interprets your measured power reading into a standardized "watts per kilogram" or "watts per pound" value. This value can then be compared to established standards or previous tests to determine if the core is in good condition.

Stator Core Loss Test Calculator

Core length mm Inside diameter mm Back iron mm Slot depth mm Number of air ducts qty Width of air ducts mm Back iron weight kg

Target back iron flux density tesla Test voltage volts Test frequency hertz

Actual loop turns turns Calculated flux density tesla Calculated test current amps Minimum cable size 0.75 mm² or 20 AWG Calculated apparent power kVA Target volts per turn volts

Measured volts per turn volts Measured real power watts Actual back iron flux density tesla Core loss watts/kg

Instructions for Stator Core Loss Test Calculator

This calculator helps determine the core loss of a stator, which is crucial for assessing its condition.

Unit Selection: Choose between SI (millimeters) and USCS (inches). Input values will convert automatically when you switch units.
Stator Dimensions: Enter all physical dimensions of the stator core. 'Back iron' refers to the thickness of the core behind the stator slots.
Test Parameters:
- Target back iron flux density: The desired magnetic flux density for the test. 1.32 Tesla is a common value for silicon steel.
- Test voltage & frequency: The voltage and frequency of the power source used for the test.
Measured Values:
- Measured volts per turn: After wrapping a test coil, measure the voltage induced per single turn.
- Measured real power: The power in watts consumed during the test, as measured by a wattmeter.
Calculated Results: The calculator automatically computes key values like back iron weight, the target volts per turn to aim for, the actual flux density achieved, and the final core loss in watts per unit weight.