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Keeping Your World Up & Running®
Keeping Your World Up & Running®
Enables one person to perform a job that would typically take two people to do with the removable display. This True RMS AC/DC clamp meter allows the user to clamp around a conductor to measure the current. Also, the user can walk over to electrical controls or remove protective equipment, all while viewing real-time readings.
Enables one person to perform a job that would typically take two people to do with the removable display. This True RMS AC/DC clamp meter allows the user to clamp around a conductor to measure the current. Also, the user can walk over to electrical controls or remove protective equipment, all while viewing real-time readings.
What once took two people, now takes one
Allows one technician to do the job that would require two people. This remote display allows the user to clamp around a conductor, detach the display. Furthermore, they can walk across the room to configure controls or remove protective equipment, all while watching real-time readings.
The iFlex® Flexible Current Probe (included) expands the measurement range to 2500 A AC while providing increased display flexibility. With a cord that runs 6', you can finally measure those tight spaces, awkward sized conductors and disorganized wires.
Measurement capability
Features
To measure ac or dc voltage:
).
on the Fluke 381.To measure resistance or continuity:
. terminal.If the resistance is <30Ω, continuity is indicated by a beeper continuously sounding. If the display reads OL, the circuit is open or the resistance being measured is greater than the meters resistance range.
Visual of an AC/DC voltage measurement
To measure frequency (on the Fluke 381):
.
on the Fluke 381) to shift to Hz.“RMS” stands for root-mean-square. It comes from a mathematical formula that calculates the “effective” value (or heating value) of any ac wave shape. In electrical terms, the ac rms value is equivalent to the dc heating value of a particular waveform—voltage or current. For example, if a resistive heating element in an electric furnace is rated at 15 kilowatts (kW) of heat at 240 V ac rms, then we would get the same amount of heat if we applied 240 V of dc instead of ac.
Electrical power system components such as fuses, bus bars, conductors, and thermal elements of circuit breakers are rated in rms current because their main limitation has to do with heat dissipation. If we want to check an electrical circuit for overloading, we need to measure the rms current and compare the measured value to the rated value for the component in question.
If a current clamp is labeled and specified to respond to the true-rms value of current, it means that the clamp’s internal circuit calculates the heating value according to the rms formula. This method will give the correct heating value regardless of the current wave shape.
Certain low-cost current clamps, which don’t have true rms circuitry, use a short cut method to find the rms value.
These meters are specified to be “average responding-rms indicating.” These meters capture the rectified average of an ac waveform and scale the number by 1.1 to calculate the rms value. In other words, the value they display is not a true value, but rather is a calculated value based on an assumption about the wave shape. The average responding method works for pure sine waves but can lead to large reading errors up to 40 percent, when a waveform is distorted by nonlinear loads such as adjustable speed drives or computers. The table below gives some examples of the way the two different types of meters respond to different wave shapes.
Some true-rms clamp meters are ac coupled, which gives the rms value of only the ac component of a waveform. (This dates from the time when a majority of measurements in the electrical industry were predominately sinusoidal with no dc offset.) To measure the rms with an ac coupled clamp meter, first measure the rms value of the ac component. Then measure the waveform on the dc scale. Combine the ac and dc components by squaring each, adding the results, and then extracting the square root. The function AC+DC in Fluke true rms clamp meters essentially does the calculation for you.
A comparison of average responding and true-rms units
Learn more about True RMS| Electrical Specifications | |
| Range | 999.9 A |
| Resolution | 0.1 A |
| Accuracy | 2% ± 5 digits (10 to 100 Hz) 5% &plusn; 5 digits (100 to 500 Hz) |
| Crest Factor (50/60 Hz) | 3 at 500 A 2.5 at 600 A 1.42 at 1000 A Add 2% for C.F. >2 |
| AC Current via Flexible Current Probe | |
| Range | 999.9, 2500 A (45 to 500 Hz) |
| Resolution | 0.1, 1 A |
| Accuracy | 3% ± 5 digits |
| Crest Factor (50/60 Hz) | 3.0 at 1100 A 2.5 at 1400 A 1.42 at 2500 A Add 2% for C.F. >2 |
| DC Current | |
| Range | 999.9 A |
| Resolution | 0.1 A |
| Accuracy | 2.5% ± 5 digits |
Click on a category to view a selection of compatible accessories with the Fluke 381 Remote Display True RMS AC/DC Clamp Meter with iFlex.
| Electrical Specifications | |
| Range | 999.9 A |
| Resolution | 0.1 A |
| Accuracy | 2% ± 5 digits (10 to 100 Hz) 5% &plusn; 5 digits (100 to 500 Hz) |
| Crest Factor (50/60 Hz) | 3 at 500 A 2.5 at 600 A 1.42 at 1000 A Add 2% for C.F. >2 |
| AC Current via Flexible Current Probe | |
| Range | 999.9, 2500 A (45 to 500 Hz) |
| Resolution | 0.1, 1 A |
| Accuracy | 3% ± 5 digits |
| Crest Factor (50/60 Hz) | 3.0 at 1100 A 2.5 at 1400 A 1.42 at 2500 A Add 2% for C.F. >2 |
| DC Current | |
| Range | 999.9 A |
| Resolution | 0.1 A |
| Accuracy | 2.5% ± 5 digits |
Click on a category to view a selection of compatible accessories with the Fluke 381 Remote Display True RMS AC/DC Clamp Meter with iFlex.
