Abstract: A line isolation monitor (LIM) indicates the maximum hazard current of an ungrounded polyphase power distribution system. The LIM is microcontroller based and continuously monitors a fault impedance of the distribution system. The fault impedance is determined by the LIM by injecting a continuous sine wave measurement current into a ground terminal to generate a measurement voltage across the fault impedance. Using the measurement voltage and current, the LIM calculates the fault impedance and, using this impedance, calculates the hazard current based on the maximum line to ground voltage of the ungrounded system. The hazard current is displayed and if it exceeds a predetermined threshold, the LIM will provide audio and visual alarms. A serial communications channel allows the LIM to communicate with other intelligent devices. The LIM has means for self-calibration and self-testing while on-line and during a power-up sequence. Line frequency is also determined by the LIM.

Abstract: A line isolation monitor (LIM) indicates the maximum hazard current of an ungrounded polyphase power distribution system. The LIM is microcontroller based and continuously monitors a fault impedance for each phase of the distribution system. The fault impedance is determined by the LIM by injecting a continuous sine wave measurement current into a ground terminal to generate a measurement voltage across the fault impedance. Using the measurement voltage and current, the LIM calculates the fault impedance and, using this impedance, calculates the hazard current based on the maximum line to ground voltage of the ungrounded system. The LIM has means for self-calibration and self-testing while on-line and during a power-up sequence. These tests compare measured and theoretical values of circuit parameters of voltage and current sensing circuits.

Abstract: An apparatus controls the treatment of water that flows through a cooling system. The electrical conductivity of the water is sensed. A valve control opens a system drain valve when the sensed conductivity is greater than a threshold, and closes the drain valve when the conductivity drops below the threshold by a given amount. The water drained form the system is replenished through an inlet and a mechanism measures the volume of water added to the cooling system. Chemicals to treat the water are fed into the system when specified volumes of water have been added. The sensing of conductivity can be inhibited for a certain period following the application of the chemicals. A possible system malfunction is indicated when the conductivity does not drop below the threshold after the drain valve is open for a given period of time.

Abstract: An apparatus controls treatment of water flowing through a boiler and includes a device that monitors the conductivity of the water. A controller opens a drain valve at periodic intervals, and closes the drain valve when the conductivity drops below a defined threshold. A mechanism measures the volume of water that flows into the boiler and a chemical is added to the water when a specified amount of water has flowed into the boiler. Alternatively the application of the chemical can occur at regular intervals of time. The chemical is applied for a user definable period of time. The application of the chemical is suspended when the cessation of water flow into the boiler is detected.

Abstract: A tag suitable for attachment to an animal includes a programmed microprocessor which monitors the activity of the animal. Activity is measured by counting the closures of a mercury switch, and when the current activity exceeds a reference activity by a preset amount, a light emitting diode is energized. Four light emitting diodes are provided to indicate four separate levels of activity.

Abstract: An animal such as a dairy cow carries a transponder unit which includes a motion sensor. When the animal comes within range of a transceiver unit, it is interrogated and the transponder unit transmits data which identifies the animal and indicates the number of movements of the animal. The number of animal movements increase dramatically during estrus and a record is kept on each animal to determine when this occurs. Data received at the transceiver is processed by a microprocessor based system which operates to insure the received data is correct. It also assembles the data and outputs it to a printer.

Abstract: An open loop servo controller for controlling motors which drive a solar energy utilizing device about its azimuth and altitude axis to track the sun. The controller has a central processor and elements for inputting data corresponding with the present day of the year, the hour of the day, the minute of the hour and with the latitude and longitude of the device installation. Memories store program data, and tables of data corresponding with the declination of the sun on any day and of other mathematical functions. The processor uses the data to calculate the azimuth and altitude angles of the sun itself within every minute of the day and causes signals to be produced which result in motor controllers causing the motors to turn the device through azimuth and altitude axes angles corresponding with the calculated angles.

Abstract: A transceiver unit includes an oscillator which generates a pulse train to a transceiver counter that connects to a display. The pulse train is also coupled by means of coils to a counter contained in a portable transponder unit which attaches to the animal. The transponder unit counter counts in synchronism with the transceiver counter and it generates a reset pulse when it counts a preselected number of the pulses. This reset pulse is coupled by means of coils to the transceiver unit. The preselected number corresponds to the identification number of the animal and the reset pulse reads this number out of the transceiver counter to the display.