Phase firing circuits

Claim 2

A control circuit for switching single and polyphase supplies, said control circuit comprising thyristor means for controlling connection of electrical load means to the electrical supply, firing means for controlling triggering of said thyristor means such that the electrical load means is connected to the electrical supply at or neaR zero volts, and a single pole switching means located within a single phase of the supply for controlling energization of said firing means.

Claim 3

A control circuit for switching single phase electrical supplies, said control circuit comprising thyristor means for controlling the connection of electrical load means to a single phase electrical supply, firing means for controlling triggering of said thyristor means such that the electrical load means is connected to said single phase supply when the single phase supply voltage is near zero volts, and a single pole switch connected in series with said firing means across said single phase for controlling energization of said firing means.

Claim 4

A control circuit for switching single phase electrical supplies, said control circuit comprising thyristor means for controlling the connection of electrical load means to a single phase electrical supply, firing means for controlling triggering of said thyristor means such that the electrical load means is connected to said single phase supply when the single phase supply voltage is near zero volts, and a single pole switch connected in series with said firing means across said single phase for controlling energization of said firing means.

Claim 5

A control circuit for switching polyphase electrical supplies, said control circuit comprising thyristor means located in each phase of a polyphase supply for controlling the connection of electrical load means to the supply, firing means associated with each phase for respectively triggering corresponding ones of said thyristor means, a single pole switching means for, when actuated, causing energization of a first said firing means, and means for connecting said thyristor means and said firing means such that energization of said first firing means causes triggering of a said thyristor means in the succeeding phase and triggering of that thyristor means causes energization of further firing means in the same phase and such that the firing means of each of the other phases triggers the thyristor means in each succeeding phase whereby each phase sequentially switches the succeeding phase, said sequential switching occurring as each phase passes through zero volts in both positive and negative senses.

Claim 6

A control circuit for switching polyphase electrical supplies, said control circuit comprising thyristor means located in each phase of a polyphase supply for controlling the connection of electrical load means to the supply, firing means associated with each phase for respectively triggering corresponding ones of said thyristor means, a single pole switching means for, when actuated, causing energization of a first said firing means, and means for connecting said thyristor means and said firing means such that energization of said first firing means causes triggering of a said thyristor means in the succeeding phase and triggering of that thyristor means causes energization of further firing means in the same phase and such that the firing means of each of the other phases triggers the thyristor means in each succeeding phase whereby each phase sequentially switches the succeeding phase, said sequential switching occurring as each phase passes through zero volts in both positive and negative senses.

Claim 7

A control circuit for switching polyphase electrical supplies, said control circuit comprising thyristor means located in each phase of a polyphase supply for controlling the connection of electrical load means to the supply, firing means associated with each phase for respectively triggering corresponding ones of said thyristor means, a single pole switching means for, when actuated, causing energization of a first said firing means, and means for connecting said thyristor means and said firing means such that energization of said first firing means causes triggering of a said thyristor means in the preceding phase and triggering of that thyristor means causes energization of further firing means in the same phase and such that the firing means of each of the other phases triggers the thyristor means in each preceding phase whereby each phase sequentially switches the preceding phase, said sequential switching occurring as each phase passes through zero volts in both positive and negative senses.

Claim 8

A control circuit for switching polyphase electrical supplies, said control circuit comprising thyristor means located in each phase of a polyphase supply for controlling the connection of electrical load means to the supply, firing means associated with each phase for respectively triggering corresponding ones of said thyristor means, a single pole switching means for, when actuated, causing energization of a first said firing means, and means for connecting said thyristor means and said firing means such that energization of said first firing means causes triggering of a said thyristor means in the preceding phase and triggering of that thyristor means causes energization of further firing means in the same phase and such that the firing means of each of the other phases triggers the thyristor means in each preceding phase whereby each phase sequentially switches the preceding phase, said sequential switching occurring as each phase passes through zero volts in both positive and negative senses.

Claim 9

A control circuit as claimed in claim 1, wherein said firing means comprise transformer means having two independent, rectified and current limited outputs of opposed polarity.

Claim 10

A control circuit as claimed in claim 1, wherein said thyristor means comprise a plurality of silicon controlled rectifiers connected within each phase to switch positive and negative half cycles respectively.

Claim 11

A control circuit as claimed in claim 1, wherein said firing means comprises a transformer with a single secondary winding and said thyristor means comprise triacs.

Claim 12

A control circuit as claimed in claim 1, wherein said firing means comprise a transformer providing non-rectified, non-current limited control of said thyristor means.

Claim 13

A control circuit as claimed in claim 1, wherein said single pole switching means comprises a semi-conductor controlled by a cross-over point detector.

Claim 14

A control circuit as claimed in claim 1, wherein said single pole switching means comprises a semi-conductor controlled by a burst firing module.

Claim 15

A control circuit as claimed in claim 1, wherein said single pole switching means is a semi-conductor controlled by an adjustable ON/OFF ratio controller.

Claim 16

A control circuit as claimed in claim 1 for use in the speed control of mOtors.

Claim 17

A control circuit as claimed in claim 2, wherein a voltage control device is provided to protect said thyristor means.

Claim 18

A control circuit as claimed in claim 1, wherein further switching means are provided for isolating part of said firing means for supplying half power.

Claim 19

A control circuit as claimed in claim 1, for use in controlling power supplied to a blade bonding machine.