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<blockquote data-quote="jeallen01" data-source="post: 1150636" data-attributes="member: 176704">Incoming spikes and, probably inductive surges (which would&nbsp; be relatively a lot slower) from small domestic appliance motors, are very fast (a few uS or mS) and so you'd need a metering device that reacts much faster than a typical wattmeter to &quot;see&quot; them!Typically (having done quite a bit of this when running kit through CE marking EM immunity certification tests!) you use a specialised hi-spec radio receiver (from the likes of Rhode &amp; Schwarz, etc.) together with a specialised matching network between the mains source (also to a specific set of impedance/frequency characteristics) and the EUT, with the feed to the receiver tapped off from that network. The results are either recorded within the receiver or fed to an external recorder, whilst at the same time very carefully monitoring/recording the performance of the unit against a set of acceptable performance characteristics as defined by the manufacturer to determine the effects, if any, of the incoming interference spikes or surges.The incoming spikes and surges differ considerably and are generated by different types of (very expensive!) waveform generators to internationally standardised and repeatable waveforms/timimgs.All of the above are intended to allow realistic and repeatable assessments and comparisons of measurements made in differing test labs around the World!By comparison, a typical &quot;wattmeter&quot; is designed to average (or read the RMS value of) the current &amp; voltage (and thus power) passing through its measuring circuits to give a realistic reading of the power consumption of the EUT in a &quot;typical&quot; operating environment - and if it didn't have some sort of averaging/RMS function then you wouldn't be able to get useful results because the needle or display would typically be &quot;flying all over the place&quot;!I think that should help to explain that the measurements made by, and perceptable effects noted by, a typical &quot;wattmeter&quot; in a &quot;typical&quot; operating environment are not really comparable (nor are they intended to be!) with the results obtained under controlled test laboratory conditions - and that's certainly very true for immunity testing because it often identifies performance effects/defects that are not perceptable to the &quot;human brain&quot; (&amp;/or a &quot;wattmeter&quot;).As a result, dedicated immunity testing can identify potential performance shortfalls/glitches that cannot be identified, or even observed, using a &quot;wattmeter&quot;, but nevertheless can/will affect the performance of kit (especially sensitive electronic kit like sat receivers) in day-to-day service. It can also help to determine if a domestic appliance is susceptible to incoming spikes/surges - after all, you wouldn't want your washing machine to run your woolens through a long high temp &quot;cotton&quot; programme when you'd set it to a short low temp &quot;woolens&quot; programme because an incoming spike/surge had caused the microprocessor to &quot;glitch&quot;, would you???</blockquote>

[QUOTE="jeallen01, post: 1150636, member: 176704"] Incoming spikes and, probably inductive surges [I](which would be relatively a lot slower)[/I] from small domestic appliance motors, are very fast [I](a few uS or mS) [/I]and so you'd need a metering device that reacts much faster than a typical wattmeter to "see" them! Typically [I](having done quite a bit of this when running kit through CE marking EM immunity certification tests!) [/I]you use a specialised hi-spec radio receiver [I](from the likes of Rhode & Schwarz, etc.) [/I]together with a specialised matching network between the mains source[I] (also to a specific set of impedance/frequency characteristics)[/I] and the EUT, with the feed to the receiver tapped off from that network. The results are either recorded within the receiver or fed to an external recorder, whilst at the same time very carefully monitoring/recording the performance of the unit against a set of acceptable performance characteristics as defined by the manufacturer to determine the effects, if any, of the incoming interference spikes or surges. The incoming spikes and surges differ considerably and are generated by different types of (very expensive!) waveform generators to internationally standardised and repeatable waveforms/timimgs. All of the above are intended to allow realistic and repeatable assessments and comparisons of measurements made in differing test labs around the World! By comparison, a typical "wattmeter" is designed to [U]average (or read the RMS value of[/U]) the current & voltage (and thus power) passing through its measuring circuits to give a realistic reading of the power consumption of the EUT in a "typical" operating environment - and if it didn't have some sort of averaging/RMS function then you wouldn't be able to get useful results because the needle or display would typically be "flying all over the place"! I think that should help to explain that the measurements made by, and perceptable effects noted by, a typical "wattmeter" in a "typical" operating environment are not really comparable [I](nor are they intended to be!)[/I] with the results obtained under controlled test laboratory conditions - and that's certainly very true for immunity testing because it often identifies performance effects/defects that are not perceptable to the "human brain" (&/or a "wattmeter"). As a result, dedicated immunity testing can identify potential performance shortfalls/glitches that cannot be identified, or even observed, using a "wattmeter", but nevertheless can/will affect the performance of kit [I](especially sensitive electronic kit like sat receivers) [/I]in day-to-day service. It can also help to determine if a domestic appliance is susceptible to incoming spikes/surges - after all, you wouldn't want your washing machine to run your woolens through a long high temp "cotton" programme when you'd set it to a short low temp "woolens" programme because an incoming spike/surge had caused the microprocessor to "glitch", [I]would you???[/I] [/QUOTE]

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