Electrical Testing — Technical Knowledge Hub
SM System designs and manufactures automatic electrical testing systems for motors, stators, rotors, windings, coils and transformers. This section collects the complete technical documentation for every technical test integrated in our products — from fundamental DC measurements to advanced non-destructive diagnostics. Select a test type below to access the full engineering guide.
Why Systematic Technical Tests Matter
Electric motors, stators, and windings are subject to a wide range of failure modes — from microscopic insulation defects introduced during manufacturing to progressive degradation caused by thermal cycling and voltage transients in service. Systematic technical tests at every stage of production and maintenance allow manufacturers and maintenance teams to detect these issues before they reach the field, reducing warranty costs, unplanned downtime, and safety hazards.
The IEC (International Electrotechnical Commission) — the primary international standards body governing electrical machine testing, through standards such as IEC 60034 for rotating machines and IEC 60068 for environmental testing — recommends a complete test protocol covering both DC and impulse methods as the most effective approach for ensuring winding quality and insulation integrity.
The six technical tests documented in this section represent the core suite of electrical quality tests applied in modern motor manufacturing and maintenance environments. From the winding resistance test — which establishes baseline conductor quality using the precise 4-wire Kelvin method — to the partial discharge measurement — which identifies micro-voids in insulation before they trigger progressive failure — each test targets a specific failure mode and provides data that no other method can replicate.
What distinguishes professional technical tests from simple continuity checks is their ability to produce quantitative, traceable data: resistance values in milliohms, insulation levels in megaohms, leakage currents in milliamps, and oscillographic waveform signatures that carry fingerprint-level diagnostic information about winding condition. This data forms the backbone of both end-of-line production quality control and structured predictive maintenance programmes.
SM System integrates all six test types into its automatic testing systems — from the compact bench-top TST-F-LAB to the fully automated multi-station TST-S-5000 series — making it possible to execute a complete technical test sequence in a single automated cycle, with full data logging, database storage, and export capabilities for Industry 4.0 traceability.
Technical Guides by Test Type
Winding Resistance Test
Measure stator winding resistance with the 4-wire Kelvin method. Detects phase imbalances, open circuits and manufacturing defects — the precision benchmark for quality-critical motor production.
Insulation Resistance Test
Quantify the insulation integrity of motor windings using DC voltage. Identifies moisture ingress, contamination and degradation before they cause ground faults or winding failures.
Hipot — Dielectric Withstand Test
Apply controlled high voltage to stress the insulation system beyond rated conditions. The standard test for IEC, CE and UL compliance on motors, stators, transformers and windings.
Surge Test
Detect turn-to-turn insulation defects with fast-rising impulse voltages. The only method capable of revealing inter-turn faults invisible to DC or low-frequency tests — essential for end-of-line winding QC.
Squirrel-Cage Rotor Testing
Non-destructive, bar-by-bar electromagnetic scan of die-cast aluminium rotors. Identifies broken bars, porosity, blowhole defects and cage eccentricity before motor assembly.