Rockwell Automation Technologies Incorporated

Andrew L Tsang

Burt Sacherski

James Edward Dogul

Steven Robert Tambeau

Todd Bubar

Arvind Ananthanarayanan

Timothy P Wolfe

Arvid Ananthanarayanan

A cable pull switch includes a polychotomous sensor configured to provide a reading of at least one of a plurality of values, the reading corresponding to a tension on a pull cable or a linear displacement of an end of a pull cable. A processor coupled to the polychotomous cable pull sensor configured to determine a rate of change of the value of the reading from the sensor and determine an occurrence of a cable pull event, the determination based on the determined rate of change of the value, and determine whether the rate of change of the value of an electrical resistance through the polychotomous cable pull sensor is below a threshold rate of change value, and adjust an upper pull threshold value to a new upper pull threshold value that is based on a present reading of the value of the electrical resistance through the strain gauge.

Safety switch and associated methods

An apparatus for an imbalance test includes a strain measurement module that measures a strain voltage across terminals of a strain gauge. The strain voltage is representative of an amount of force on the strain gauge. The apparatus includes a test measurement module that measures a test voltage across the terminals of the strain gauge while a test resistor is connected in parallel with a resistor of the strain gauge. The test resistor is connected while the test measurement module measures the test voltage and is disconnected while the strain module measures strain voltage. The apparatus includes an average module that calculates an average strain voltage from two strain voltage measurements. The strain voltages are measured preceding and after the test voltage measurement. The apparatus includes a difference module that determines a difference voltage. The difference voltage is a difference between the average strain voltage and the test voltage.

Safety switch with imbalance test

A cable pull switch includes a polychotomous sensor configured to provide a reading of at least one of a plurality of values, the reading corresponding to a tension on a pull cable or a linear displacement of an end of a pull cable. A processing device is configured to receive the reading, determine whether a value of the reading is outside of a non-tripped value window, a limit edge being a pull threshold value, and responsively generate an output signal indicative of a cable pull event. Other features and improvements are described.

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Lowell, MA, United States of America

Andrew L Tsang