UT203 provides a lot of user comfort and a very pleasant feature – measuring of a DC current without interrupting a measured circuit. However UT204 is different from its “weaker” brother in one essential thing – it enable measuring of a true RMS value of alternating signals (TRMS).
As we know, usual multi meters usually deploy a simple rectifier and an RC cell and they´re calibrated to show an effective value of AC voltage – supposing an ideally sinusoidal shape of a measured variable.
In many cases, a non-TRMS multi meter is fully sufficient, but still more frequently we meet devices, which by their power consumption significantly deform originally sinusoidal shape of a mains line voltage. A vast majority of new devices is equipped with switch-mode power supplies deforming a sinusoid, as they draw current for charging of input capacitors mainly on a top of a sinusoid. This situation is partially better at power supplies with a power factor correction (PFC), but even in these cases it´s never an ideal load. At any difference from an ideal sinusoid the accuracy of a common meter significantly drops down and the error can exceed tens of percent’s. Similar situation is also at various DC/AC inverters (for example 12VDC/230VAC), whose output is usually only an approximated sinus.
That´s why if exact measurement matters to us, it´s more certain to measure by a device equipped by a TRMS measurement. There are many types with this function on the market, and in a segment of clamp multi meters it´s for example the above mentioned UT204, which moreover offers a lot of other functionality for an excellent price.
Detailed information and comparison of UT203/ UT204 will provide you the UT204 datasheet and the UT204 datasheet and UT203-204 user guide. We keep Uni Trend UT204 as a standard – immediately available item.
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