Gains

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 I_c is the control current and R_c is the resistance of the control circuit. An increase ΔI_c in the control current produces an increase ΔI_L in the load current with a corresponding increase of power ΔP_c applied to the control circuit, and ΔP_L in the output power to the load. Hence

The power gain is defined by

[7-34]

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

[7-35]

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

[7-36]