Fluke Corporation have published a series of application notes to help electricians and electronics professionals do advanced electrical testing with their Fluke digital multimeters (DMMs). The application notes are available from Fluke Australia , a subsidiary of Fluke Corporation.
Advanced DMMs, such as the Fluke 289 industrial trending digital multimeter and Fluke 287 Electronics multimeter, incorporate a multitude of advanced test and measurement capabilities. Some users may be unsure of how those capabilities are used, or why the tools are designed as they are.
Fluke Corporation’s application notes, also available through the Fluke website, are written and illustrated to explain the use of advanced DMMs, so Fluke users can solve problems and benefit from their Fluke test tools.
One new feature is the dual impedance capability built into the Fluke 289 industrial trending digital multimeter/DMM. Most DMMs sold today for testing industrial, electrical and electronic systems have high impedance input circuits greater than 1 megohm. This means that when the DMM is placed across a circuit for a measurement, it will have little impact on circuit performance. This is the desired effect for most voltage measurement applications, and is especially important for sensitive electronics or control circuits.
Older troubleshooting tools generally have low impedance input circuitry at around 10 kilohms or less. While these tools are not fooled by ghost voltages, they should only be used for testing circuits where the low impedance will not negatively impact or alter circuit performance.
With dual impedance meters, technicians can troubleshoot sensitive electronic or control circuits, as well as circuits that may contain ghost voltages and can determine whether voltage is present on a circuit.