The Fluke 117 True RMS Digital Multimeteris a great all-round multimeter for the electrical engineer working on both AC & DC industrial systems it offers AC/DC Current range, Resistance, Frequency and Capacitance Measurements plus It’s the only Fluke Digital Multimeter with all the special Fluke measurement features such as VoltAlert™ - Non-contact AC Voltage Detection, AutoVolt - Automatic AC/DC Voltage selection and Loz - Low input impedance measurements to prevent induced voltages.
The Fluke 117 True RMS Digital Multimeter displays both voltage and current readings with a 6000 count resolution, and tests for frequency, capacitance, resistance and continuity. It’s got a large back lit display that aids visibility in poorly lit areas.
A new unique feature for this Fluke 110 Series Multimeter is VoltAlert™ this technology allows for non-contact voltage detection. The VoltAlert function detects the presence of AC voltage, sounds an audible tone and activates a red LED indicator light on the top centre of the LCD display. Using this feature before making a contact measurement can add an extra layer of safety. Users should, of course, still test for the presence of voltage using test leads with the meter in the volts setting.
The Fluke Auto-V feature automatically determines whether the measured signal is ac voltage or dc voltage and then selects the correct function and range. The Fluke LoZ function is a ‘Low Impedance’ (Z) test feature. This feature presents a low impedance input to the circuit under test. This low impedance reduces the possibility of false readings and the pick-up of induced voltages and improves accuracy when testing to determine absence or presence of voltage.
Induced voltages occur from having energized circuits and non-energized wiring located in close proximity to each other, such as in the same conduit or cable tray. This condition forms a capacitor and allows capacitive coupling between the energized wiring and the adjacent unused wiring.
When you place your multimeter leads between the open circuit and the neutral conductor, you effectively complete the circuit through the input of the multimeter. The capacitance between the connected, hot conductor and the floating conductor forms a voltage divider in conjunction with the multimeter input impedance. The multimeter then measures and displays the resulting voltage value.
Most digital multimeters available today have an input impedance that's high enough to show the capacitive coupled voltage, giving a false impression of a live conductor. The meter is actually measuring voltage coupled into the disconnected conductor. However, these voltages, at times, can be 80-85% of what the "hard" voltage should be. If not recognized as an induced voltage, additional time, effort and money will be lost troubleshooting circuit problems.
The most common places to encounter induced voltages are blown fuses in distribution panels, unused cable runs or electrical wiring in existing conduit, open ground or neutral on a 230V circuit or where 230V control circuits are used to control the function of production lines line. Some amount of induced voltage can be coupled from the hot side to the open side across the blown fuse. When facilities or buildings are built and wired, it's very common for electricians to pull extra wire through the conduit for future use. These wires are typically left unconnected until needed, but are subject to capacitive inductance. In the case of the control circuits, these circuits are typically located adjacent to unused control lines, thereby creating a potential for an induced voltage measurement.
The Fluke FTPL-1 Fused Test Lead Set includes Fluke’s SureGrip Fused Test Probe and Fluke TL224 Silicon Test Leads.
With the Fluke FTPL-1 Fused Test Lead Set if the probe fuse does blow, the special fused test probes will still allow the meter to indicate live voltage, helping to prevent a possible misreading of no voltage present. Rated to CAT III 1000 V, these probes have removable tip guards for reduced probe tip exposure.
