Solid state a/c motor protector system

Claim 2

A protective circuit for a current drawing load supplied by a source of energy comprising in combination, contactor means for connecting and disconnecting the load and the source; a plurality of magnitude sensitive means each responsive to a different range of current magnitudes; indicators respectively associated with each of said magnitude sensitive means; sensing means responsive to the load current to energize the indicators by actuating the magnitude sensitive means; threshold means responsive to a predetermined level of load current under control of the sensing means to actuate the contactor means to disconnect the load; further indicating means operated by the threshold means; and said magnitude sensitive means being selected to have respectively overlapping ranges of current magnitudes to which they are sensitive in order that more than a single indicator may be energized at a time.

Claim 3

The protective circuit of claim 1 wherein the load comprises a motor, and further comprising a jog switch means for by-passing the protective circuit to operate the motor independently thereof.

Claim 4

The protective circuit of claim 1 comprising an integrator circuit connected to be responsive at a predetermined point in one of said ranges to initiate timing for a predetermined time period if the motor remains operating At load current in accordance with or above said point, and to disengage the motor via said contactor if said predetermined amount of time elapses during said operation.

Claim 5

The protective circuit of claim 3 comprising means for resetting the integrator for timing said predetermined period if the motor load current causes operation below said point during said predetermined time period.

Claim 6

The protective circuit of claim 3 wherein the integrator circuit is characterized by an inverse slope characteristic relative to the load current characteristic whereby as the load current increases above the amount of load current corresponding to said predetermined point, the integrator circuit time decreases.

Claim 7

The protective circuit of claim 1 further comprising a delayed regulator for interposing a predetermined amount of time delay when the load is first receiving current to disable the protective circuitry until said predetermined time has elapsed.

Claim 8

A protective circuit for a current drawing load supplied by a multi-phase source of energy comprising in combination, a contactor means for connecting and disconnecting the load and the source; a plurality of magnitude sensitive means each responsive to a different range of current magnitudes; indicators respectively associated with each of said magnitude sensitive means; sensing means response to the load current in one phase to energize the indicators by actuating the magnitude sensitive means; threshold means responsive to a predetermined level of load current in said one phase under control of the sensing means to actuate the contactor means to disconnect the load; connection means from at least one of the magnitude sensitive means to actuate the contactor means to disconnect the load at a different predetermined value; further indicating means operated by the threshold means; and wherein each magnitude sensitive means comprises a solid-state circuit having upper and lower voltage-sensitive means respectively operative at the upper and lower ranges of current magnitudes.

Claim 9

A protective circuit for a current drawing load supplied by a multi-phase source of energy comprising in combination, a contactor means for connecting and disconnecting the load and the source; a plurality of magnitude sensitive means each responsive to a different range of current magnitudes; indicators respectively associated with each of said magnitude sensitive means; sensing means response to the load current in one phase to energize the indicators by actuating the magnitude sensitive means; threshold means responsive to a predetermined level of load current in said one phase under control of the sensing means to actuate the contactor means to disconnect the load; connection means from at least one of the magnitude sensitive means to actuate the contactor means to disconnect the load at a different predetermined value; further indicating means operated by the threshold means; and wherein each magnitude sensitive means comprises a solid-state circuit having upper and lower voltage-sensitive means respectively operative at the upper and lower ranges of current magnitudes.

Claim 12

The method of claim 8 including the further step of interrupting the energy supply to the load when the load current remains above a lesser predetermined value for a predetermined period of time.

Claim 13

A protective circuit for a current drawing load supplied by a multi-phase source of energy comprising in combination, contactor means for connecting and disconnecting the load and the source; a plurality of magnitude sensitive means each responsive to a different range of overlapping current magnitudes; indicators respectively associated with each of said magnitude sensitive means; sensing means responsive to the load current in one phase to energize the indicators by actuating the magnitude sensitive means; threshold means responsive to a predetermined level of load current in said one phase under control of the sensing means to actuate the contactor means to disconnect the load; and connection means from at least one of the magnitude sensitive means to actuate the contactor means to disconnect the load at a different predetermined value.

Claim 14

A protective circuit for a current drawing load supplied by a multi-phase source of energy comprising in combination, contactor means for connecting and disconnecting the load and the source; a plurality of magnitude sensitive means each responsive to a different range of overlapping current magnitudes; indicators respectively associated with each of said magnitude sensitive means; sensing means responsive to the load current in one phase to energize the indicators by actuating the magnitude sensitive means; threshold means responsive to a predetermined level of load current in said one phase under control of the sensing means to actuate the contactor means to disconnect the load; and connection means from at least one of the magnitude sensitive means to actuate the contactor means to disconnect the load at a different predetermined value.