Hazeltine Corporation

Irving W Cahalan

Paul Seiter

Michael La Clair

John Weber

A portable test receiver for field maintenance of a remote sensor monitoring system for underground transformers. The apparatus uses a phase locked loop method to demodulate the DPSK modulation of the remote monitor transmitter. The apparatus is battery operated and easily moved to permit monitoring of spot networks and critical locations for maintenance work. The apparatus features a single software driven display offering good visibility with low current drain. Decoding the transmitter signal is accomplished by using the crystal oscillator circuit of the transmitter is used to generate a reference which is compared to the transmitter signal to detect phase flips. Since the apparatus is battery-powered, there is no AC power to provide 'zero' crossing points of the monitored transmitter. Bit timing is provided by taking advantage of the nulls at the 60 cycle 'zero' crossings found in the transmitter signal.

Portable test receiver for remote monitoring system

A remote monitoring system (RMS) receiver which operates at a dual baud rate. The operating rate is selected to be the same as the rate being used by remote equipment originating the data link with the receiver. A modem associated with the receiver provides an indicator signal indicating phase shift keying (a high baud rate) or frequency shift keying (a low baud rate) is being received from the remote equipment. The indicator signal is used to select the baud rate of a programmable baud rate generator of the RMS receiver. This controls the baud rate signal which is supplied to an asynchronous interface controlling data transfer between the receiver and the modem.

Remote monitoring system receiver with dual baud rate selector

The oil detecting switch includes a light oil float switch, a water float switch and a heavy oil float switch. When the light oil float switch is closed, a relay is activated energizing a light oil indicator light and its associated coil. The coil is part of a relay which inhibits pumping action. When the water float switch is activated, the inhibiting relay is bypassed so that pumping action can continue. When the heavy oil float switch is activated and closed, a relay is activated which energizes a heavy oil indicator light and its associated coil. The coil is part of a relay which inhibits pumping action. The light oil indicator light, its associated coil and the water indicator light are bypassed when the heavy oil float switch is activated. The status of the float switches is monitored by an analog-to-digital converter associated with a Remote Monitoring System Transmitter.

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Huntington Station, NY, United States of America

Irving W Cahalan