Solid-state voltage switching circuit

In a voltage switch circuit for receiving an a.c. voltage across a pair of terminals thereof and having a pair of thyristors for selectively establishing a circuit path therebetween, a first one of said thyristors having an anode connected to one of said terminals, a cathode connected to the other of said terminals, and a gate, and a second one of said thyristors having an anode connected to said other terminal, a cathode connected to said one terminal, and a gate, including switch means actuable between two states, for directly connecting and short circuiting said gate of said first thyristor to said cathode thereof and said gate of said second thyristor to said cathode thereof in the first state to render said thyristors nonconductive, and for connecting said gate of said first thyristor to said gate of said second thyristor in the second state to render said thyristors conductive, said switch means in said second state isolating the gates of said thyristors from the cathodes thereof, whereby said thyristors require decreased gate turn on currents to be rendered conductive and when conductive establish said circuit path, and when nonconductive interrupt said circuit path and have increased dv/dt withstand capabilities.

A solid-state relay for receiving a voltage across a pair of terminals and having a silicon controlled rectifier (SCR) for selectively establishing a circuit path therebetween, said SCR having an anode connectable to one of said terminals, a cathode connectable to the other of said terminals, and a gate, including switch means having alternately operable contacts for selectively turning the circuit on and off, said switch means including a first contact connected between said gate and said anode and a second contact connected between said gate and said cathode;

• said first contact being open and said second contact being closed whenever said switch means is turned off for directly connecting and short circuiting said gate to said cathode and for isolating said gate from said anode, thereby to render said SCR nonconductive and to increase the dv/dt withstand capability thereof;
• said first contact being closed and said second contact being open whenever said switch means is turned on for connecting said gate to said anode and for isolating said gate from said cathode, whereby said SCR requires a decreased gate turn on current to be rendered conductive and is rendered conductive to establish said circuit path.

In a voltage switching circuit for receiving a voltage across a pair of terminals and having a thyristor for selectively establishing a circuit path therebetween, said thyristor having an anode connected to one of said terminals, a cathode connected to the other of said terminals, and a gate, including a source of reference potential;

• and switch means actuable between two states for directly connecting and short circuiting said gate to said source of reference potential and isolating said gate from said anode in a first state to render said thyristor nonconductive and for connecting said gate to said anode and isolating said gate from said source of reference potential in a second state to render said thyristor conductive, whereby said thyristor requires a decreased gate turn on current to be rendered conductive and when conductive establishes said circuit path, and when nonconductive interrupts said circuit path and has a dv/dt withstand capability in accordance with the value of said reference potential.

In a voltage switching circuit for receiving a voltage across a pair of terminals and having a silicon controlled rectifier for selectively establishing a circuit path therebetween, said silicon controlled rectifier having an anode connected to one of said terminals, a cathode connected to the other of said terminals, and a gate, including a source of reference potential;

• and switch means actuable between two states, said switch means including a first contact connected between said gate and said anode and a second contact connected between said gate and said source of reference potential, said first contact being open and said second contact being closed in said first state to render said silicon controlled rectifier nonconductive and to control the dv/dt withstand capability thereof, said first contact being closed and said second contact being open in said second state to isolate said gate from said source of reference potential and to render said silicon controlled rectifier conductive to establish said circuit path, whereby said silicon controlled rectifier requires a decreased gate turn on current to be rendered conductive and when conductive establishes said circuit path, and when nonconductive interrupts said circuit path and has a dv/dt withstand capability in accordance with the value of said reference potential.