EN
LVD High Voltage Test
LVD high voltage (dielectric withstand, hipot) test: overvoltage trial on insulation, puncture monitoring and safe procedure with signed reports.
The LVD high voltage test (dielectric withstand, hipot) is the voltage stress trial verifying whether the insulation of low voltage equipment withstands the foreseen overvoltage. While the insulation test measures resistance, the high voltage test challenges the puncture limit; the two are complements, not substitutes. The test applies in type trials, routine quality control and post-maintenance verification.
Method and Values
- Test voltage: Set by manufacturer and standard; the common practical approach is 1000 V + 2×Vn (about twice nominal plus 1000 V AC) or the DC equivalent. Duration is typically 1 second (type) or 5-60 seconds (routine per manufacturer condition).
- Acceptance: No puncture or flashover at the defined voltage and the leakage current must stay below the upper limit; the trip current is preset and the instrument cuts without sustaining an arc.
- Measurement points: Live conductors are shorted and stressed as a group against the body, and also primary-secondary; measurement is not made through the earthing.
- Electronic protection: PLC, drive and sensor supplies are disconnected so they do not see the test voltage; the reduced test value (e.g. 500 V) in the manufacturer guide governs — otherwise the trial creates a fault.
Safety
The hipot test carries energy: the zone is insulated, earthed and posted with warnings; the operator uses two-hand control and insulating gloves-mat, third parties stand outside distance. Discharging capacitive loads (cable, filter, long line) after test is mandatory — residual charge on touchable metal is hazardous. Dry air and clean insulator surfaces are required; humidity inflates surface leakage and fakes a breakdown impression. Before test, the equipment's insulation resistance and earth continuity must be verified — applying high voltage to damaged insulation is both dangerous and destructive.
Legislation and Outcome
The test is part of the electrical safety verification programme under 2014/35/EU LVD, 2006/42/EC and the Work Equipment Regulation. References: IEC 61010-1 (safety of measuring equipment, dielectric test), TS EN 60204-1 and product IEC/TS EN series. The result is reported as a signed protocol with test voltage, duration, trip-leakage values and the pass decision; on failure the puncture point and repair proposal are added. High voltage tests are in our PL Analysis and LVD Tests set; for the rest of the chain see Insulation and Earth Continuity, or contact us for an appointment. Each circuit record lists applied voltage, hold time, leakage reading and ambient conditions, so next year's same-point value compares one-to-one and silent insulation drift is seen before it fails.
FAQ on LVD High Voltage Test
It is the non-destructive acceptance test verifying whether the insulation carries a defined withstand voltage above the operating voltage (TS EN 60204-1 practice: 1000 V + 2 x Ue for 1 minute; shortened to 1 second in factory series test) for a set time. The aim is to measure the leakage without an energy burst if there is an insulation weakness-piercing defect-moisture bridge, with a trip-current setting applied under device-earth-bonding-insulation precautions.
AC is the basis in production-acceptance because it stresses both polarities like operating voltage and catches capacitive-distributed defects. DC (e.g. 2-3 times) gives similar stress at lower energy; it catches insulation degradation-soft breakdown early; but capacitive-cable-emulsion field distribution demands different reading. On devices with sensitive power electronics, the standard-manufacturer permitted voltage-curve profile is applied; over-test damage risk is managed.
Flashover-arc above defined leakage, break-through-burn-carbon mark, trip-emergency cut, instability under voltage. Before rejection; dirt-moisture-temperature equilibrium-wrong connection (correction-conditioning-retest) is separated. The failed device is corrected by clean-dry-change-repair and retested. Series production runs acceptance-threshold statistics (SPC); prototype runs type-test logic; the result is documented with a calibrated device protocol-report.
An HV test carries lethal energy: wire cage-barricade-isolated zone, two-person work-key-power cut, earthing-bonding continuity (PE first), shielded high inductance device, automatic discharge, emergency stop; personnel authority certificate-dry floor-insulating mat. No conductor-part access during test; capacitive discharge verification after. The report carries test voltage-duration-leakage value-acceptance decision-persons; it is filed compatible with the energy-cut high voltage work permit (High Current Regulation) regime.