Superposition theorem. In a linear, bilateral network having more than one source, the current and voltage in any part of the network can be found by adding algebraically the effect of each source separately. All other sources are temporarily killed by short-circuiting voltage sources and opening current sources.
Thevenin's theorem. Any network with two open terminals A and B can be replaced by a single voltage source VTH in series with a single resistance RTH connected to terminals A and B. Voltage VTH is the voltage produced by the network across terminals A and B. Resistance RTH is the resistance across open terminals A and B with all voltage sources short-circuited.
Norton's theorem. Any two-terminal network can be replaced by a single current source IN in parallel with a single resistance RN. The value of IN is the current produced by the network through the short-circuited terminals. RN is the resistance across the open terminals with all voltage sources short-circuited.
Millman's theorem. The common voltage across parallel branches with different V sources can be determined with Formula (10-1).
A voltage source V with its series R can be converted to an equivalent current source I with parallel R. Similarly, a current source I with a parallel R can be converted to a voltage source V with a series R. The value of I is V/R or V is I x R. The value of R is the same for both sources. However, R is in series with V but in parallel with I.
The conversion between delta and wye networks is illustrated in Fig. 10–21. To convert from one network to the other, Formula (10-2) or (10-3) is used.
