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Three general types of gain are associated with saturable reactors that are premagnetized with direct current. These are power gain, ampere-turn gain, and current gain.

Power gain

The power output to the load is

and the power input to the control circuit is

where Ic is the control current and Rc is the resistance of the control circuit. An increase ΔIc in the control current produces an increase ΔIL in the load current with a corresponding increase of power ΔPc applied to the control circuit, and ΔPL in the output power to the load. Hence

The power gain is defined by


Ampere-turn gain

By following a process similar to the one that led to the definition of power gain, the ampere-turn gain is defined by


which shows, on the basis of the law of equal ampere turns (Eq. 7-24), that for the series-connected gate windings

and for parallel-connected gate windings

Current gain

The current gain is defined, in terms of the ampere-turns gain on the basis of the law of equal ampere turns, by


Last Update: 2011-01-12