HM8118: Transformer measurement with incorrect results (ID #591)
The different measurement results are depending on the loss of the iron core as well as the unknown state of the pre-magnetized core.
The coil, which is to measure, depends on the frequency as well as on the current measurement voltage.
The device defines the values for L, R and C by measuring the impedance and the appropriate phase angle. Depending on the angle, the resulting value is inductive, capacitive or real (L,C,R).
This means: The value of the impedance increases with raising voltage. Furthermore the phase angle depends heavily (by counter magnetization and iron core losses) on the measurement frequency (viewable in "Z-Theta" mode).
The values of a short-circuited secondary side almost correspond to the losses of a coil. These losses are depending on frequency and measurement voltage.