Relay circuits employing a triac to prevent arcing

Claim 2

Circuitry for controlling the flow of current from an AC source to a load including, in combination: a. relay contact means connected between a load terminal and input terminal means; b. electroresponsive means coupled between said input terminal means and said relay contact means for closing said relay contact means a given time after an input voltage is applied to said electroresponsive means: c. a multilayer semiconductor switch connected in parallel with said relay contact means, said multilayer semiconductor switch having a gate region connected to a control electrode and responsive to negative and positive polarity signals to shunt said relay contact means; d. first circuit means including a diode and a first resistor serially connected between said control electrode of said semiconductor switch and said input terminal means, said first circuit means applying a turn-on current to said semiconductor switch prior to the time said relay contact means close; and e. second circuit means connected to said first circuit means and providing a current to said control electrode of said multilayer semiconductor switch to maintain conduction in said multilayer semiconductor switch after said relay contact means opens.

Claim 3

The circuitry defined in claim 1 wherein said second circuit means includes a second resistor and a capacitor connected to said first resistor, said capacitor discharging into said control electrode of said semiconductor switch to maintain said semiconductor switch conducting subsequent to the opening of said relay contact means.

Claim 4

The circuitry defined in claim 2 wherein said diode is connected between a common junction between said first and second resistors and said input terminal means.

Claim 5

The circuitry defined in claim 2 wherein said diode is connected in series with said relay means across said input terminal means, said relay means including a relay coil which is electromechanically coupled to said relay contact means for closing said relay contact means.

Claim 6

The circuitry defined in claim 2 wherein said relay means includes a relay coil which is connected across said input terminal means, said circuitry further including a diode connected between said input terminal means and said common junction between said first and second resistors.

Claim 7

The circuitry defined in claim 5 wherein said diode is connected directly between said common junction and said input terminal means.

Claim 8

The circuitry defined in claim 2 which further includes resistance-capacitance network means connected in shunt with said semiconductor switch and responsive to rapid changes in AC line voltage to prevent triggering of said semiconductor switch.

Claim 9

The circuitry defined in claim 7 wherein said resistance-capacitance network means consists of a resistor and capacitor connected in series across said semiconductor switch and across said relay contact means.

Claim 10

Circuitry for controlling the flow of current from an AC source to a load including, in combination: a. relay contact means connected between a first input terminal and a load terminal; b. electroresponsive means coupled between the first input terminal and said relay contact means for closing said relay contact means a given time after an input voltage is applied to said electroresponsive means; c. a semiconductor triac connected in parallel with said relay contact means and having a gate electrode for receiving gate current for turning on said semiconductor triac; d. a first resistor connected to the gate electrode of said semiconductor triac; e. a second resistor connected to said firsT resistor; f. charge storage means connected between said second resistor and a second input terminal, said means receiving a charge sufficient to sustain conduction in said semiconductor triac after an energizing voltage is removed from said electroresponsive means; and g. interconnecting circuit means connected between said first input terminal and a point intermediate said first and second resistors so that said first resistor limits the turn-on gate current to said semiconductor triac when the latter is turned on and said storage means discharges through said first and second resistors into the gate electrode of said semiconductor triac to sustain conduction therein and prevent arcing in said relay contact means after an energizing voltage is removed from said electroresponsive means.

Claim 11

Circuitry for controlling the flow of current from an AC source to a load including, in combination: a. relay contact means connected between a first input terminal and a load terminal; b. electroresponsive means coupled between the first input terminal and said relay contact means for closing said relay contact means a given time after an input voltage is applied to said electroresponsive means; c. a semiconductor triac connected in parallel with said relay contact means and having a gate electrode for receiving gate current for turning on said semiconductor triac; d. a first resistor connected to the gate electrode of said semiconductor triac; e. a second resistor connected to said firsT resistor; f. charge storage means connected between said second resistor and a second input terminal, said means receiving a charge sufficient to sustain conduction in said semiconductor triac after an energizing voltage is removed from said electroresponsive means; and g. interconnecting circuit means connected between said first input terminal and a point intermediate said first and second resistors so that said first resistor limits the turn-on gate current to said semiconductor triac when the latter is turned on and said storage means discharges through said first and second resistors into the gate electrode of said semiconductor triac to sustain conduction therein and prevent arcing in said relay contact means after an energizing voltage is removed from said electroresponsive means.

Claim 12

Circuitry defined in claim 9 wherein said semiconductor triac includes parallel PNPN conductive paths which are alternately rendered conductive upon the application of positive and negative polarity signals to said gate electrode of said triac.

Claim 13

The circuitry defined in claim 9 wherein said interconnecting circuit means includes a diode connected between said input terminal and said point intermediate said first and second resistors, so that said semiconductor triac and said capacitor are energized by a rectified voltage of one polarity.

Claim 14

The circuitry defined in claim ll wherein: a. said diode is connected in parallel with said electroresponsive means; and b. said electroresponsive means includes an electromechanical relay including an inductor serially connected through a switch across a pair of input terminals for receiving an AC energizing voltage when said switch is closed.

Claim 15

The circuitry defined in claim ll wherein said diode is connected between said input terminal and one end of an inductor in said electroresponsive means so that said electroresponsive means, said semiconductor triac, and said capacitor are all energized by a rectified energizing voltage.