Rotary phase converter having circuity for switching windings to provide reduced starting current with rapid, dependable starting

In a rotary dynamoelectric converter for converting single-phase, alternatinng current to three-phase, alternating current, said converter being of the type having three sets of windings wired in either delta or wye configuration, wherein each set of windinngs consists of two coils normally connected in parallel within the respective winding, said converter further having three leads connected to the delta or wye configurations, with two of the leads being connected to a source of single-phase alternating current and with a run capacitor connected between one of the first two leads and the third lead, such that three-phase current can be drawn from the three leads when the dynamoelectric converter is running at its normal operating speed, an improvement consisting of

• an electrically activated switch member having first and second operating positions wherein the first operating position connects the two coils of each respective winding in series with each other and the second operating position connects the two coils of each respective winding in parallel with each other;
• a first electrical activator that activates said switch member to its first operating position when single phase current is initially connected to the first two leads and the dynamoelectric converter has not yet attained its operating speed;
• a second electrical activator that deactivates said first activator and further activates said switch member to its second operating position when the dynamoelectric converter comes up to its normal operating speed
• a voltage monitor for monitoring the voltage developed across the run capacitor;
• a monitor switch that is connected to source of electrical energy, with said monitor being controlled by the voltage monitor to close only when the voltage across the run capacitor attains a preselected magnitude;
• a relay coil in series with said monitor switch so that the relay coil is energized when the monitor switch is closed;
• said first electrical activator comprises a first relay switch which when closed provides elestrical current to activities said switch member to its first operating position, said first relay switch being resposive to said relay coil to close when the relay coil is not energized and to open when the relay coil is energized;
• and
• said second electrical activator comprises a second relay switch when closed provides electical current to activate said switch member to its second operating position, said second relay switch being responsive to said relay coil to close when the relay coil is energized and to open when the relay coilis not energized.