John Fluke Mfg. Co., Inc.

Fluke Corporation

Robert M Greenberg

Glen A Meldrum

Alan W McRobert

A clamp-on multimeter measures alternating current flow in an electrical conductor. The multimeter includes a display, a housing including the display, a first sensor, a second sensor, a processor and an integrator. The first sensor has a magnetizable material core and inductively senses the alternating current. The first sensor includes a first clamp portion fixed to the housing and a second clamp portion pivotally coupled to the first clamp portion. The second sensor includes a Rogowski coil that has a non-magnetic core and inductively senses the alternating current. The processor receives an input signal in a first voltage range and sends an output signal to the digital display. The integrator scales a signal from the second sensor in a second voltage range to the first voltage range. The housing includes the processor, the integrator, and a selector configured to select the input signal to the processor from one of the first sensor and the integrator.

Clamp-on multimeters including a Rogowski coil for measuring alternating current in a conductor

A min/max time stamp for a multimeter provides display of minimum and maximum measured values recorded since enabling a min/max function. The minimum and maximum values, as well as a present value, may be displayed, together with the relative or absolute time at which the measured minimum or maximum occurred. An alert signal is generated to indicate a new maximum or a new minimum measurement.

Multimeter having min/max time stamp

An instrument having a continuity test feature wherein a change in continuity state from open-to-short or short-to-open is captured and displayed. A comparator provides continuity state information for a circuit under test. A storage device receives the state information and provides logic indicative of the continuity state which is read by a controller that executes a continuity capture program initiated by keypad or function selector input. A first transition between different continuity states is captured during a present capture cycle and is displayed in a form indicative of the type of transition captured. Subsequent transitions during the present capture cycle are ignored.

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Marysville, WA, United States of America

Robert M Greenberg