Abstract: A telemetry system for use with AC power lines, comprising a pulse transmitter connected to the lines for generating pulses on the power lines only in a selected portion of each full cycle of the power line voltage waveshape. The system further comprises a pulse receiver including first means for counting pulses in the selected portion and second means for counting pulses in another portion of each full cycle. The two counts are compared (one is subtracted from the other) over a plurality of full cycles to produce a net pulse count. Since the noise signals appear throughout the cycles and, over a sufficient number of full cycles, are present in substantially equal numbers in both portions, the subtraction of the two counts essentially eliminates the noise pulses. Any remaining pulses are those produced by the transmitter and may be processed as needed, and false tripping due to noise signals is avoided.

Abstract: This disclosure relates to a system for stabilizing a permanent magnet synchronous motor that does not have a rotor starting cage or windings. The system includes a dc source, an inverter connected to the dc source for converting the dc to a multi-phase ac, and an ac synchronous motor connected to receive the multi-phase ac, the motor being constructed without a starting cage or winding. The system further includes means for sensing variations in the motor power angle, and a control circuit connected to respond to the variations and to cause the inverter output to vary such as to generate an ac component of torque that leads in phase the power angle variations at the natural frequency of the rotor of the motor. The inverter output may be varied by modulating the applied frequency, the dc bus current to the inverter, or the inverter phase angle.

Abstract: This disclosure relates to an electrical power transfer system for matching a load to a DC source such as a solar array. The system tracks the power output of the source under varying operating conditions and matches the load to the source to maintain peak power conditions. The system senses the voltage and the current of the source, incrementally changes the volt-ampere operating point of the source and thereby changes its incremental resistance, and adjusts the load to the level where the ratio of the DC source voltage to the DC source current is substantially equal to the incremental resistance.

Abstract: This disclosure relates to control apparatus and particularly to a triggered switch connected in a first or controlled circuit and a trigger device connected in a second circuit. AC currents flow through the first and second circuits and there is a changing phase angle between the currents. Further, the current level in the second circuit changes. When the phase angle is greater than a certain value and the current level in the second circuit is above a certain level, the trigger device triggers the switch and energizes the first circuit. At angles below the value and current levels below the certain level, the switch is not triggered. Thus, the changing phase angle may be utilized to control the first circuit. The triggered switch is a thyristor type of device such as a triac, and the trigger device is preferably a reed switch. The control apparatus is particularly useful in controlling the start winding of a single phase AC motor.