Per-Unit Current vs. Saturation Factor (SF)
Per-Unit Current vs. Per-Unit Voltage
The saturation characteristics of the magnetizing flux paths can be specified in two forms as described below. Saturation may be enabled or disabled through the Mutual Saturation input parameter.
Saturation factor is defined as the ratio:
VUnsaturated is the voltage if the initial slope of the V-I curve was maintained, and VSaturated is the actual saturated voltage. With this format, the mutual saturation curve is specified as pairs of points per-unit current vs. saturation factor.
The first point should be (0.0, 1.0) and the second point should be (I2M, 1.0) where I2M is the current in per unit at which the onset of saturation occurs. The voltage corresponding to I2M is derived from the Unsaturated Magnetizing Reactance input parameter, which is specified under the Explicit Data Format area.
The remaining 8 points should be in pairs of per-unit current and their corresponding saturation factors. Thus, a maximum of 8 additional pairs of points can be specified. If less than 8 additional pairs are used the last pair must be (-1.0, -1.0) after which all points are ignored. The points entered should have monotonically decreasing factors with monotonically increasing currents.
The second format is to specify the open-circuit test results in pairs of per-unit current and per-unit voltage (Ipu, Vpu). The first point should be (0.0, 0.0) and the second point should be (I2M, V2M), where I2M is the current in per unit at which the onset of saturation occurs and V2M is the corresponding per-unit voltage and should be equal to I2M(XL0+XM0). Inconsistency will result if V2M does not satisfy this condition.
A maximum of 10 pairs can be specified. If less than 10 pairs are used the last pair must be (-1.0, -1.0) and the points thereafter are ignored.
