Westinghouse Electric Corporation

Eaton Corporation

Marlan L Winter

Joseph C Engel

Mark E Innes

Gary F Saletta

Denis A Mueller

Edward C Prather

A controller incorporating a push button station controls a plurality of electrical contactors in a modular multicontactor system using three-wire serial data links. All information exchange is initiated and controlled by the controller using a simple four-byte protocol which places very little burden on the contactors. The controller can also communicate with and receive commands from devices on a network through an interface using the same four-byte message protocol, but with the interface acting as the master and the controller as the slave. When used in a reversing and two-speed motor controller configuration, the controller manages sequencing of the contactors, including delays, and passes thermal image data between contactors.

Digital modular microprocessor based electrical contactor system

Process and apparatus for calibrating an electrical device such as a circuit breaker, motor controller or monitor is taught. A precision power supply device is interconnected by way of appropriate input channels to the device to be calibrated for supplying a precise accurate calibration variable as an input. A personal computer PC is interlinked by way of a communications network with the apparatus to be calibrated and is also interlinked with the precision supply device so that the personal computer PC has available the exact value of input variable utilized. Gain adjustment calibration is made by supplying the predetermined value of circuit variables, for instance 10 amperes or 120V to the input terminals of the device being calibrated. Upon command, the personal computer PC instructs the device being calibrated to deliver to the personal computer PC those values of input variable which the device being calibrated interprets as the input variable value. The personal computer PC compares this value with the actual value and generates a correction factor which the personal computer PC sends back to the device being calibrated for storage in an EEPROM. Consequently, during subsequent use after the calibration procedure has been completed and the calibration features have been safely 'locked' away in the EEPROM, all readings will be adjusted by the aforementioned calibration factor to compensate for errors which may exist in other portions of the device being calibrated.

Process for auto calibration of a microprocessor based overcurrent

Microprocessor based apparatus for controlling an electrical load, such as a motor, includes an external capacitor for storing an analog equivalent of a digitally modeled heat state signal, such as the I.sup.2 t characteristic of the motor. The voltage on the capacitor decays to mimic motor cooling when the microprocessor is powered down with deenergization of the motor. The stored analog signal is updated by periodically converting the analog signal to a retrieved digital heat state signal which is compared to the latest calculated value of the heat state signal. If the retrieved value is below the present calculated value, an input/output port is set to a high output state to charge up the storage capacitor. If the retrieved value is above the calculated value, the port is configured as an output port with a low state to reduce the voltage on the capacitor. When the retrieved heat state signal equals the calculated signal, the port is configured as an input port with a high impedance to maintain the stored value on the capacitor. To maintain accuracy over a wide range with an 8-bit processor, the selected limiting value of the I.sup.2 t characteristic is loaded into a large register and shifted n bits toward the most significant bit of the register until a ONE appears on the most significant bit. On power-up the 8-bit retrieved heat state signal is then loaded into the most significant bits of the register and shifted the n bits away from the most significant bit to bring it into the range of the selected limit value for the I.sup.2 t characteristic. For updating the stored heat state signal, the latest calculated heat state signal is shifted n bits toward the most significant bit for comparison with the retrieved digital heat state signal.

Growing community of inventors

Hendersonville, NC, United States of America

Marlan L Winter