When a stator bar is installed in its slot, the conductive slot coating is in electrical contact with the grounded core and the geometry is defined by the slot. Pull the bar out for a laboratory test, and you have to reproduce that slot-electrode arrangement with temporary electrodes. Get that reconstruction wrong and you measure the electrode system,… Read More: Guard Ring Electrodes for Tan Delta Bar & Coil Testing »
Tan δ is a small number measured against a demanding background. You are resolving a resistive current a thousand times smaller than the capacitive current beside it, at high voltage, with stray capacitance to earth trying to corrupt the reading. The instrument matters. IEC 60034-27-3 recognizes three ways to make the measurement, and each one exists to solve… Read More: How Tan Delta Is Measured: Bridges and Digital Systems »
IEC 60034-27-3 is the standard that governs dielectric dissipation factor — tan δ — measurement on the stator winding insulation of rotating machines. This is a section-by-section walk through the document, in the order the standard itself uses, so you can find and understand any clause quickly. For the test in practice rather than the document structure, start… Read More: IEC 60034-27-3 Explained: Clause-by-Clause Guide »
A single tan δ reading tells you how lossy a winding’s insulation is at one voltage. What the insulation does as the voltage rises tells you why. That behavior — the slope of the tan δ curve — is where the diagnostic value lives, and it is captured by two numbers: delta tan delta and the tip-up. This… Read More: Tan Delta Tip-Up and Delta Tan Delta Explained »
Every insulation system leaks a little. Apply AC voltage across ground-wall insulation and the current splits into two parts: a large capacitive current that leads the voltage by 90°, and a small resistive current in phase with it that turns into heat. The dissipation factor — tan δ — is the ratio of those two. It is the… Read More: Dissipation Factor (tan δ) Test for Stator Windings »
The DC hipot test is the most consequential offline test you can run on a stator winding. It applies a high DC voltage — well above operating levels — to the groundwall insulation and holds it there. If the insulation fails during the test, you know before the machine goes back into service. If it passes, you have… Read More: DC Hipot Testing of Motor Stator Windings (IEEE 95) »