...with Surge / Impulse Technology

Surge testing:

high-voltage impulses with a fixed rise time arerepeatedly applied to a coil by capacitor discharge. The resulting “response“ waveform (LC oscillation) is graphically displayed and available for visual or automatic evaluation (by means of program- med tolerance criteria) and comparision i.e. with a reference pat- tern. The outstanding property of this method is a real turn-to-turn insulation stress: because of the extremely short rise time of the impulse, high potential is created between neighboring turns or layers of the same coils while the impulse “travels“ as a surge wave through the winding. In the case of damaged insulation small discharges or arcs of very low energy will occur – depending on the kind and location of the fault. These effects are visible in the waveform characteristic.

...one step farther

Partial Discharge Tests or Online PD Monitoring

can detect aging or danger for an insulation system atan incipient stage. Unlike the conventional method (which is based on excitation with power-frequent AC Hipot and stan-dardized for general evaluation of insulation) Baker goes in another direction: to detect PDs within electric windings, we apply impulses with ultra-fast rise times (around 100 ns). The micro discharges which appear result in “frequencies“ of around 50 MHz. This demands the highest performance from the capturing device. Example: when 3-phase machines with modern VFDs (PWM) are run, theentrances of the phases are exposed to fast-rising voltage tran-sients. At the same time PDs can happen which deteriorate theinsulation and reduce the motor lifetime, supported by long feedercables and insufficient filtering. Whether amotor is “inverter-proof“ depends stronglyon the transient pulse strength of its win-ding. Baker PD Systems offer both off-linesimulation and online real-time recording of these events. For this application we useexclusive technologies such as Laplace filtering.

Baker Instrument supplies several technical solutions and methods for PD testing, depending on the application case.