Abstract: A motor controller is adaptable to a wide range of motor currents by using an integrator circuit having an additional feedback arrangement for affecting the effective time constant of the integrator under specified conditions. The operational amplifier has an amplifier having a first input, a second input, and an output, an input resistor connected between an input of the operational amplifier and the first input of the amplifier, and a feedback impedance connected between the output of the amplifier and the first input of the amplifier. A voltage at the input of the operational amplifier is compared with a voltage at the first input of the amplifier. An auxiliary current path for the feedback impedance is provided when the voltage at the input of the operational amplifier has a predetermined relationship to the voltage at the input of the amplifier.

Abstract: A motor controller with means responsive to a motor condition for preventing termination of power to the motor in response to fault conditions when these fault conditions occur during start-up of the motor.

Abstract: A motor controller receives a signal proportional to motor current, integrates that signal during the high currents associated with starting, and holds a level during normal operation at speed within a maximum current limit. When an overload causes the motor to trip and there is a loss of power to the controller, a memory holds the level for a predetermined time to prevent an immediate restart of the motor.

Abstract: This disclosure depicts a novel abort cycle timer circuit for use with an AC source of electrical power and for operating electrical controls for machinery. The circuit provides a substantially DC voltage and current, first and second relays with normally open and normally closed contacts and a timing abort circuit. Opening a first of two switches causes the second of the two relays to energize after a time delay. Opening both switches causes the second relay to deenergize after a predetermined time. The novel circuit has improved immunity to electrical and magnetic noise.

Abstract: A solid state overload relay protective apparatus for electric motors which includes not only the overload feature, but the additional features of underload and single phase protection. Small current transformers for sensing the current flow in each phase of the motor are utilized, like those found in the ground fault sensing art because a current-to-voltage converter circuit reflects a short circuit back to the secondary of the transformers. The signal from the current transformers which is proportional to the sensed current in the motor is fed through the converter, a scaling and summing amplifier adjustable for a wide range of motor full load currents, an ideal diode peak detector, a time integrator amplifier, to one input of a comparator circuit having a trip reference voltage signal at another input. The comparator provides an output signal to a transistorized trip level circuit that deenergizes a coil of an overload relay opening its contacts and interrupting power to the motor.