The Doble M4000 M4100 Power Analysis generates a 0-12 kV test signal with an internal sine wave generator, a 3 kVA power amplifier and a step-up isolation transformer.
The Doble M4000 M4100 Power Analysis then measures the voltage and current of the specimen and a reference impedance by periodically sampling instantaneous values with an A/D converter.
Calculations and test results are reported by converting the sampled data into vector (magnitude and phase) quantities and applying conventional AC circuit theory. All reported results – including power loss, power factor and capacitance – are derived from the vector voltage and current.
The M4000 M4100 rejects interference through the judicious application of shielding, line-synchronized reversal, and line frequency modulation (FM). The first two techniques are similar to those employed in the earlier Doble M2H product line. The FM technique involves running tests at sinusoidal frequencies 5% (or even 10%, if necessary) above and below the line frequency and averaging the results. The choice is user configurable.
The inevitable interference current component is removed from the sampled data set before test results are calculated using synchronous detection. This is a mathematical process that separates out a single frequency component in a given signal. It is analogous to a bandpass filter centered at the test frequency. Synchronous detection is also useful for removing harmonic distortion and random noise in the test signal itself.
Diagnostic capabilities of the Doble M4000 M4100 system:
• 12 kV Power Factor/Tan-Delta capacitance testing to assess insulation condition & dielectric loss
• High stress and high accuracy 10 kV TTR with the dobleTTR Capacitor
• Winding Leakage Reactance testing with the M4110 to detect winding deformation or damage
• 10 kV Single-Phase Excitation Current testing to detect degraded turn-to-turn insulation damage and magnetic circuit anomalies