Electrical interstage control

Claim 2

Electrical control apparatus for use with an AC source, comprising a main circuit including a load, back-to-back solid state main valve means in the main circuit, transformers having secondaries controlling the valve means, a control circuit, backto-back solid state auxiliary valve means in the control circuit, said transformers having primaries controlled by the auxiliary valve means, the main and auxiliary valve means being arranged for mutually counteracting effect responsive to respective phases of the AC, rectifiers respectively associated with the auxiliary valve means and operative for passing current at the respective half cycles of the AC to the associated auxiliary valve means, and further including independent variable control means for performing a gating function on the auxiliary valve means including conductors to the auxiliary valve means and a common conductor, the last means including a potentiometer connected between the gating conductors and the common conductor, and further including a supplemental DC source across the potentiometer for controlling the gating of the auxiliary valve means.

Claim 3

Electrical control apparatus according to claim 1 wherein the means for producing the gating current is operative for infinitely varying the current throughout full range, and adapted for adjustment for varying without shutting off the auxiliary control means, or for shutting it off, selectively.

Claim 4

Electrical control apparatus for use with an AC source, a main circuit including a load, and including main back-to-back SCR''s and secondaries of main transfoRmers controlling the gates of those SCR''s, a control circuit, auxiliary (and) back-to-back SCR''s in the control circuit in series with the primaries of said transformers, the auxiliary SCR''s, through the current passing therethrough and through said primaries, controlling the gates in the main SCR''s and thereby the current through those SCR''s and thus through the load, (second) additional transformers in the control circuit in series with the gates of the auxiliary SCR''s arranged in counteraction to the main transformers, capacitors in series with the additional transformers, and potentiometer means operative for controlling the auxiliary SCR''s independently of the (second) additional transformers.

Claim 5

Electrical control apparatus for use with an AC source, a main circuit including a load, and including main back-to-back SCR''s and secondaries of main transfoRmers controlling the gates of those SCR''s, a control circuit, auxiliary (and) back-to-back SCR''s in the control circuit in series with the primaries of said transformers, the auxiliary SCR''s, through the current passing therethrough and through said primaries, controlling the gates in the main SCR''s and thereby the current through those SCR''s and thus through the load, (second) additional transformers in the control circuit in series with the gates of the auxiliary SCR''s arranged in counteraction to the main transformers, capacitors in series with the additional transformers, and potentiometer means operative for controlling the auxiliary SCR''s independently of the (second) additional transformers.

Claim 6

Electrical control apparatus according to claim 3 and including a DC source and the potentiometer means is operative through the DC source for controlling the auxiliary SCR''s.

Claim 7

Electrical control apparatus for use with an AC source, and including a pair of conductors including a load, a main control component in one of the conductors and including back-to-back SCR''s, and secondaries of transformers controlling the gates of those SCR''s, a control circuit including a pair of conductors adapted for connection with an AC source, the main circuit and control circuit being connected with AC sources of relatively greater and lesser voltage, the control circuit including a pair of back-to-back auxiliary SCR''s connected with the conductors of the control circuit and the primaries of said transformers in series with respective ones of the auxiliary SCR''s, the main and auxiliary SCR''s being arranged for mutual counteraction in respective phases of the AC a common conductor interconnecting the bases of the auxiliary SCR''s, branch conductors connecting the gates of the auxiliary SCR''s, additional transformers interconnecting said branches and said common conductor, and capacitors in series with respective additional transformers, a potentiometer interconnected between said common conductor and said branch conductors and a DC source connected across the potentiometer, the potentiometer being operative for directly controlling the auxiliary SCR''s according to the potential output DC independently of the AC, and acting through the gates of the auxiliary SCR''s controlling the primaries of said transformers and thereby through the secondaries of those same transformers controlling the gates of the main SCR''s and in turn controlling the current through the main circuit to the load.

Claim 8

Electrical control apparatus for use with an AC source, and including a pair of conductors including a load, a main control component in one of the conductors and including back-to-back SCR''s, and secondaries of transformers controlling the gates of those SCR''s, a control circuit including a pair of conductors adapted for connection with an AC source, the main circuit and control circuit being connected with AC sources of relatively greater and lesser voltage, the control circuit including a pair of back-to-back auxiliary SCR''s connected with the conductors of the control circuit and the primaries of said transformers in series with respective ones of the auxiliary SCR''s, the main and auxiliary SCR''s being arranged for mutual counteraction in respective phases of the AC a common conductor interconnecting the bases of the auxiliary SCR''s, branch conductors connecting the gates of the auxiliary SCR''s, additional transformers interconnecting said branches and said common conductor, and capacitors in series with respective additional transformers, a potentiometer interconnected between said common conductor and said branch conductors and a DC source connected across the potentiometer, the potentiometer being operative for directly controlling the auxiliary SCR''s according to the potential output DC independently of the AC, and acting through the gates of the auxiliary SCR''s controlling the primaries of said transformers and thereby through the secondaries of those same transformers controlling the gates of the main SCR''s and in turn controlling the current through the main circuit to the load.

Claim 9

Electrical control apparatus according to claim 5 and including cabinet means having a plurality of compartments heat insulated from each other, the main SCR''s and said main transformers being in one of the compartments, and the auxiliary SCR''s being in the other of the compartments.