The 5288a is a manual tunable 12 kV, 40 kVA inductor, to be used with the MIDAS 2881 system to address higher DUT capacitance, typically used on large rotating machines or other high capacitive load while testing on-site. The variable inductor is connected in parallel with the capacitive test object CX forming a parallel resonant circuit. By adjusting the inductance the resonant point can be reached. At this resonance point the inductor compensates the reactive power required by the DUT capacitance and only the small portion of real power (ohmic losses) is needed to be fed by the Midas 2881. This arrangement enables measurement of capacitances up to 1.06 μf at 10 kV and up to 875 nF at 12 kV.

Applications when combined with MIDAS 2881
• Measuring power factor (capacitance and tan d) of rotating machines on site
• Measuring partial discharges of large rotating machines on site (requires DDX9121b and 9230)