Abstract: The present invention is a load sensor for use in an automatic portal operator such as an industrial gate operator. An induction motor is employed to move the gate. The power factor of the AC electric power supplied to the induction motor is monitored. A safety operation is triggered when the power factor indicates the motor load is greater than a predetermined amount, as when an obstruction is encountered by the gate.

Abstract: A radio remote-controlled door operator for use, among other uses, as a residential garage door operator. The transmitter contains two buttons, one to produce normal door operation and the other to set the operator into a "secure" mode wherein it will be non-responsive to further valid operating codes until reset. In addition, a second deeper level of security may be established by means of a vacation switch which disconnects the operator from the AC power supply. The operator system comprises a microprocessor which is programmed to perform various accessory functions even through the accessories may not be present. Various microprocessor inputs are tied to a false "safe" level so that even though the accessory programs are run, no outputs result and no interference with normal door operation is produced.

Abstract: An operator for a fence gate of the type which translates laterally on and in immediate parallel adjacent relationship to a section of stationary fence wherein the operator comprises an audible sounder for producing a warning signal in advance of and during the entirety of gate translation. A maximum run timer is also included for terminating gate motor drive and operation of the audible sounder.

Abstract: A control system for operating a bidirectional gate driven by a reversible electric motor includes an overload protection circuit to prevent motor current overload produced by gate obstructions and the like. The system includes control switches for operating gate opening and gate closing circuits which respectively energize the motor for rotation in opposite directions. The safety circuit includes a motor current sensing device and a first comparator which compares the level of sensed motor current with a temperature adjusted, selectable reference value and delivers a motor disabling signal to the opening and closing circuits if the sensed value exceeds the reference level. The safety circuit also includes a second comparator which compares the sensed current level with another reference value to produce the disabling signal in the event that the selected reference value of the first comparator is incorrect.