![]() ![]() Combine the ac and dc components by squaring each, adding the results, and then extracting the square root. ![]() Then measure the waveform on the dc scale. (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. Some true-rms clamp meters are ac coupled, which gives the rms value of only the ac component of a waveform. The table below gives some examples of the way the two different types of meters respond to different wave shapes. 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. 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. 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. This method will give the correct heating value regardless of the current wave shape.Ĭertain low-cost current clamps, which don’t have true rms circuitry, use a short cut method to find the rms value. 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. 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. 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.Įlectrical 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. In electrical terms, the ac rms value is equivalent to the dc heating value of a particular waveform-voltage or current. It comes from a mathematical formula that calculates the “effective” value (or heating value) of any ac wave shape. Large, easy to read, backlight display automatically sets the correct measurement range so you do not need to change switch positions while taking a measurement.Radio transmitter automatically turns off when the display is connected to the meter.The removable magnetic display can be conveniently mounted where it is easily seen.Ergonomic design fits in your hand and can be used while wearing personal protective equipment.Proprietary inrush measurement technology to filter out noise and capture motor starting current exactly as the circuit protection sees it.Integrated low pass filter and state of the art signal processing allows for use in noisy electrical environments while providing stable readings.CAT IV 600V, CAT III 1000 V safety rating.iFlex™ flexible current probe expands the measurement range to 2500 A ac while providing increased display flexibility, ability to measure awkward sized conductors and improved wire access.Wireless technology allows the display to be carried up to 30' (9.15 m) away from the point of measurement for added flexibility without interference with measurement accuracy.Min, max, average and inrush recording to capture variations automatically. ![]() 60 kµ resistance measurement with continuity detection.Frequency measurement to 500 Hz with both jaw and iFlex.True RMS ac voltage and current for accurate measurements on non-linear signals.2500 A AC current measurement with iFlex flexible current probe.1000 A AC and dc current measurement with fixed jaw.With a cord that runs 6', you can finally measure those tight spaces, awkward sized conductors and disorganized wires. The iFlex® Flexible Current Probe (included) expands the measurement range to 2500 A AC while providing increased display flexibility. Furthermore, they can walk across the room to configure controls or remove protective equipment, all while watching real-time readings. This remote display allows the user to clamp around a conductor, detach the display. Allows one technician to do the job that would require two people. ![]()
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