the short-circuit input impedance I12=0 the short-circuit forward current gain I1V2=0 Let 1=0 he open-circuit reverse voltage gain I1=0 the open-circuit output admittance

are parameters The matrix from of parameter equations:

Let us add and subtract on the right side of I2 we have

parameters equivalents admittance parameters. They parameter equivalents matrix form:

The readings of three watt-meters Ax =v an+lnx vBx=vbn+lnx vc=von+v Nx (UANia tUBvibB+Uvicdt+l(uN(ia tibB +ic)dt T Jo aNaA foBNLbB +Uvic)dt The sum of the average powers taking by the three-phase loads

If a positive current is flowing into the(+) end of the current coil while the(+) terminal of the voltage coil is positive with respect to the unmarked end, an upscale reading is obtained

A A--connection three-phase sources a, b, c--line ter min als

Three-phase sources have three Q terminals called the line terminals(a, b,c). + Neutral connection--n an b+V n bn Balanced three-phase sources may

《电路》（英文版）12-1 Three-phase voltages

An ideal transformer is a useful approximation of a very tightly coupled transformer in which the coefficient of coupling is almost unity and both the primary and secondary inductive reactance are extremely large in comparison with the terminating impedance