Rate effect motor start circuit
First Claim
1. A motor start circuit for an AC induction motor, said motor including at least one run winding coupled between a pair of AC power conductors, and a start winding, said motor start circuit having first and second connection terminals only and which are connected in series with said start winding, with the first connection terminal being connected to one end of said start winding and the second connection terminal being connected to one of said AC power conductors, for applying AC current to said start winding upon commencement of an application of AC current to said run winding and for removing said AC current from said start winding when said AC induction motor reaches an operating speed;
- the motor start circuit comprising a triac device having a main current path connected in series with said start winding and said one AC power conductor, and including means to produce a low dv/dt characteristic in the triac device so that the commencement of the application of current causes said AC current to flow through said main current path.
2 Assignments
0 Petitions
Accused Products
Abstract
A start circuit for a single phase AC induction motor employs a triac or similar device in series with the motor start or auxiliary winding. The triac device has associated circuitry so that it turns on in response to an increase in the time rate of change of applied voltage. In one version a PNP transistor and a capacitive timing circuit are employed to cut in the start winding. In another version a second, pilot triac is employed.
74 Citations
18 Claims
-
1. A motor start circuit for an AC induction motor, said motor including at least one run winding coupled between a pair of AC power conductors, and a start winding, said motor start circuit having first and second connection terminals only and which are connected in series with said start winding, with the first connection terminal being connected to one end of said start winding and the second connection terminal being connected to one of said AC power conductors, for applying AC current to said start winding upon commencement of an application of AC current to said run winding and for removing said AC current from said start winding when said AC induction motor reaches an operating speed;
- the motor start circuit comprising a triac device having a main current path connected in series with said start winding and said one AC power conductor, and including means to produce a low dv/dt characteristic in the triac device so that the commencement of the application of current causes said AC current to flow through said main current path.
- View Dependent Claims (2, 3, 4, 5)
-
6. A motor start circuit for an AC induction motor having an armature that includes at least one run winding and a start winding with said motor start circuit being connected in series with said start winding for applying an AC current from a pair of AC conductors to the start winding upon commencement of an application of AC current to said run winding, for removing the AC current from said start winding when said AC induction motor reaches an operating speed, and for reapplying the AC current to the start winding when said AC induction motor slows below said operating speed;
- the motor start circuit comprising
a first triac having first and second main electrodes coupled in series with the start winding, and a gate; a diac device having a first electrode coupled to the gate of the first triac, and a second electrode; a feedback circuit connected between one of the main electrodes of the first triac and the second electrode of the diac device; a second triac having first and second main electrodes coupled respectively to the second terminal of the diac device and to the second main terminal of the first triac, and a gate; and a bias network circuit connected in parallel with the start winding and having a reference point therein connected to the gate of the second triac. - View Dependent Claims (7, 8, 12)
- the motor start circuit comprising
-
9. A motor start circuit for an AC induction motor having an armature that includes at least one run winding and a start winding with said motor start circuit being connected in series with said start winding for applying an AC current from a pair of AC conductors to the start winding upon commencement of an application of AC current to said run winding, for removing the AC current from said start winding when said AC induction motor reaches an operating speed, and for reapplying the AC current to the start winding when said AC induction motor slows below said operating speed;
- the motor start circuit comprising
a first triac having first and second main electrodes coupled in series with the start winding, and a gate; a disc device having a first electrode coupled to the gate of the first triac, and a second electrode; a feedback circuit connected between one of the main electrodes of the first triac and the second electrode of the disc device; a second triac having first and second main electrodes coupled respectively to the second terminal of the disc device and to the second main terminal of the first triac, and a gate; and a bias network circuit connected in parallel with the start winding and having a reference point therein connected to the gate of the second triac wherein said bias network includes first and second series resistors connected in parallel across said start winding and having a junction therebetween coupled to the gate of the second triac.
- the motor start circuit comprising
-
10. A two-wire motor start circuit for an AC induction motor having an armature that includes at least one run winding and a start winding, with the motor start circuit being connected in series with the start winding, said two-wire motor start circuit having two external corrections only, with one thereof being coupled to one end of said start winding and the other thereof being coupled to one of a pair of AC conductors, for applying AC current from said pair of AC conductors to said start winding upon commencement of an application of AC current to said run winding, for removing said AC current from said start winding when said AC induction motor reaches an operating speed, and for re-applying said AC current to said start winding when said motor slows below said operating speed;
- comprising a triac device having a main current path connected in series with said start winding, and gating means sensitive to AC voltage at said start winding to gate said triac device on at the commencement of the application of said AC current, to permit the triac device to gate off when said motor reaches said operating speed, and to re-gate the triac device on in response to a change in the AC voltage at said start winding.
- View Dependent Claims (11, 13, 14, 15)
-
16. A motor start circuit for an AC induction motor having an armature that includes at least one on winding and a start winding, with said motor start circuit being connected in series with said start winding for applying an AC current from a pair of AC conductors to the start winding upon commencement of an application of AC current to said run winding, for removing the AC current from said start winding when said AC induction motor reaches an operating speed, and for reapplying the AC current to the start winding when said AC induction motor slows below said operating speed;
- the motor start circuit comprising;
an upper multivibrator circuit formed of a main triac which has cathode and anode main terminals connected in series with said start winding and a gate, an upper diac device that has a first electrode connected to the gate of said main triac and a second electrode, and an upper series RC circuit formed of an upper resistor connected to the anode main terminal of said main triac and a capacitor connected at one end to the cathode main terminal of said main triac and at its other end to the second electrode of said upper diac device; and a lower multivibrator circuit formed of a pilot triac having an anode main terminal connected to said second electrode of said upper diac device, a cathode main terminal connected to the cathode main terminal of said main triac, and a gate, a lower diac device having a first electrode connected to the gate of said pilot triac, and a lower series RC circuit formed of a lower capacitor and a lower resistor having a junction therebetween coupled to the second terminal of said lower diac device, the lower series RC circuit being connected in parallel to said start winding. - View Dependent Claims (17, 18)
- the motor start circuit comprising;
Specification