초록 ▼

A method of and apparatus for actuating an automatic transfer switch for disconnecting a motor load from a normal source of voltage and reconnecting the load to an alternate source of voltage at a time when phase differences between the output voltage of the disconnected motor load and of the altern

A method of and apparatus for actuating an automatic transfer switch for disconnecting a motor load from a normal source of voltage and reconnecting the load to an alternate source of voltage at a time when phase differences between the output voltage of the disconnected motor load and of the alternate source voltage are minimized to prevent excessive in-rush currents to the motor upon reconnection. Actuation of the transfer switch is commenced when the difference in phase between the normal source and alternate source is equal to a predetermined number of degrees depending upon whether the alternate source frequency is greater or less than the normal source frequency.

대표청구항 ▼

[ What is claimed is:] [1.] A method of limiting surge current from a transferee source of A.C. power to a load upon transfer thereto from a transferor source of A.C. power by a transfer switch comprising,monitoring the frequency of the transferor source of power,monitoring the phase of the transfer

[ What is claimed is:] [1.] A method of limiting surge current from a transferee source of A.C. power to a load upon transfer thereto from a transferor source of A.C. power by a transfer switch comprising,monitoring the frequency of the transferor source of power,monitoring the phase of the transferor source of power,monitoring the frequency of the transferee source of power,monitoring the phase of the transferor source of power,comparing the frequency of the transferor source of power with the frequency of the transferee source of power,determining the phase difference between the transferor source of power and the transferee source of power,energizing the transfer switch to effect transfer of the load from the transferor source of power to the transferee source of power when the phase difference between the transferor source of power and the transferee source of power is of a value in a first range of values, if the frequency of the transferee source of power is greater than the frequency of the transferor source of power, andenergizing the transfer switch to effect transfer of the load from the transferor source of power to the transferee source of power when the phase difference between the transferor source of power and the transferee source of power is of a value in a second range of values, if the frequency of the transferee source of power is less than the frequency of the transferor source of power.