Hi John,
OK this is getting interesting, I see your point on the distinction for “conditions”. Would it specifically say “clauses” if it meant any of the text in that section? Taking this into account, for the equipment described: So, the use of symmetrical control methods for professional equipment is permitted if a. The a|b|c conditions in 6.1 do not apply to the EUT (they don’t) b. The limits are not exceeded and it is being used for precise temperature control and there is no other technique available (not being used for precise temp control) This all hinges on whether it is using a control technique that is not permitted under Clause 6.1. Or does the provision apply for symmetrical control methods which produce large low order harmonics that are used to power heating elements, in which case the harmonic limits of Table 3 apply? I suppose that even if we get all the way through the flowchart to the end and it doesn’t meet the limits there is still a catch for If (professional equipment) then apply Clause 4. This might be the way forward. Round, like a circle, like a spiral… James From: John Woodgate [mailto:j...@woodjohn.uk] Sent: 11 October 2017 22:21 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 61000-3-2 Confusion That isn't a 'condition'. The conditions are the items in the a-b-c list in 6.1. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> Rayleigh, Essex UK On 2017-10-11 21:42, James Pawson (U3C) wrote: It was the symmetrical control for the powering of heating elements part that was the previous condition that was fulfilled. Hope this helps James ---- John Woodgate wrote ---- OK, I've sent a digest to the committee chair. Meanwhile, I noticed something that I don't quite understand: You say that "Clause 6.1 also says that symmetrical control for professional equipment is OK provided one of the “above conditions” is fulfilled (which it is, see previous bullet)" Which is the 'above condition' that the welder meets? John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> Rayleigh, Essex UK On 2017-10-11 17:08, James Pawson (U3C) wrote: Hello John, It uses phase angle control hence the concern about the harmonics generated. Manufacturer specs are single phase, 230V nominal, 3kW. Typically used at less than a 15% duty cycle, often less, in an industrial environment or powered from a generator. My *feeling* is that should be classified as professional equipment and exempted under Clause 7 but the IEV has 0 search for feelings. Thanks for your help James From: John Woodgate [ <mailto:j...@woodjohn.uk> mailto:j...@woodjohn.uk] Sent: 11 October 2017 16:49 To: <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 61000-3-2 Confusion I agree that there appears to be a need for clarification, and I will take that up with the committee responsible. But for your particular case, what is critical is the nature of the 'triac control'. Is it phase-angle control, or 'burst firing' or something else? John Woodgate OOO-Own Opinions Only J M Woodgate and Associates www.woodjohn.uk <http://www.woodjohn.uk> Rayleigh, Essex UK On 2017-10-11 15:01, James Pawson (U3C) wrote: Hi folks, I apologise as I seem to be all take and not much give on this forum at the moment; I’m trying to do a lot of learning very quickly. Someone ask a question about HDMI so that I can feel useful! Today’s question is what appears to be a contradiction in IEC 61000-3-2:2014. * The customers equipment is a triac controlled high-power PSU for welding plastic parts together using resistance heater coils * Power is over 1kW and the customer is suggesting that it is “professional equipment” which, according to Clause 7, means that harmonic “limits are not specified in this standard” * Flowchart in Clause 7 says that Clause 6.1 for allowed control methods still applies even to equipment with no limits * Clause 6.1 says symmetrical control methods which produce large low order harmonics (arguably this applies to triac control) that are used to power heating elements (applicable) provided that either input power is less than 200W (it isn’t) or the harmonic limits of Table 3 apply * Clause 6.1 also says that symmetrical control for professional equipment is OK provided one of the “above conditions” is fulfilled (which it is, see previous bullet) So we’ve gone from Clause 7 saying no limits apply to Clause 6 saying that Class D equipment limits apply. However the flowchart in Clause 7 suggests that just by being exempt from Clause 7 limits means it automatically conforms to 61000-3-2 I feel like I’m going in circles. Does anyone have any insight that might help? Much appreciated, James - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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