EN 60335 - Section 14 Transient overvoltages impulse testing. - Page 1
Forum section: electronics / projects

author: paulcolemonster
author_rank: Newbie
timestamp: June 11, 2022, 04:20:03 pm
content: HiI am developing a product that needs to comply with EN 60335. I plan to have it independently type tested, but would rather not fail first time around. The product is Class I (earthed / basic insulation).I am puzzled about the three different high voltage tests specified in EN 60335.Section 13: 1kv 1min operating temperature.Section 14: 2.92kv impulse test of clearances that cannot be inspected.Section 16: 1.25kv 1min after being exposed to moisture as per section 15.I don't understand the increase in voltage between section 13 and section 16 - surely when an appliance is up to temperature the insulation should be stronger than when it is cold and potentially damp?Also, I plan to include an on-off switch, which I will buy as a unit. (https://docs.rs-online.com/5236/A700000007283229.pdf). The datasheet specifies that it will withstand 2kv for 1 minute, but as Its clearences can't be inspected, I presume it will be subjected to the impulse test of section 14.I have access to a flash tester, which I will use for the 1kv Annex A routine tests. If I tested the switch using a flash tester, rather than an impulse tester, at the same or higher voltage, can I be sure that the switch will pass the impulse test at the test house?I'm hoping somebody more experienced than me can shed some light!Thanks,Paul

author: strawberry
author_rank: Super Contributor
timestamp: June 12, 2022, 08:42:13 am
content: my guess is 2kVrms is dielectric strength of some grease they put on contacts and springs

author: floobydust
author_rank: Super Contributor
timestamp: June 12, 2022, 09:26:03 pm
content: I believe the difference wrt hi-pot test voltages is where the test voltage is applied. The wet test is at the power cord:16.3 "A test voltage is applied between accessible metal parts and the supply cord which is wrapped with metal foil at the point where the supply cord is located in an inlet bushing and where, for appliances having a type X attachment, the supply cord is located in a cord guard or a cord anchorage with their clamping screws, if any, being tightened to two-thirds of the torque specified in Table 14. The test voltage is 1 250 V for class 0 appliances and class I appliances and 1 750 V for class II appliances."13.3 "The test voltage is applied between live parts and accessible parts, non-metallic parts being covered with metal foil. For class II constructions having intermediate metal between live parts and accessible parts, the voltage is applied across the basic insulation and the supplementary insulation."

author: Benta
author_rank: Super Contributor
timestamp: June 12, 2022, 09:42:59 pm
content: I can't help you on EN60335, but on a different point.When doing designs needing compliance testing, include the certification consultant as early in the design process as you can.This will save you time and money in the end.The belief that "well, I can read that standard myself, and in the end it's a walk through the park" to get certification is widespread and wrong.Involving the consultant early will give you valuable input on your design and allow you to correct it.I've been through this myself about a dozen times.The only problematic (and expensive) cropper was the first one. Because my mindset was just like described above.

author: floobydust
author_rank: Super Contributor
timestamp: June 13, 2022, 12:12:09 am
content: Some safety standards are organized and worded so poorly that they are very difficult to understand. The ones for appliances can be quite old and also carry many decades of legacy, which makes them spaghetti to read.Example: electric soldering irons have been around over 100 years as a heating appliance, when nothing was PE grounded or fused. UL 499 is so old, first edition 1930 I think it even started UL. Modern soldering irons use 60335-1 as well as 60335-2-45.With mains, you would not use a component with no certifications or formal approvals. Everything - the plug, line cord, fuse, fuseholder, on/off switch etc. needs to have (component-level) safety approvals. This also means the factory is qualified to make safety-related products as well i.e . a quality system is in place and audited.The on/off switch you have chosen does not show any, I do see the hi-pot and poke tests done, so a certificate for the product likely exists. You'll need to obtain it and provide (these) to the agency as part of your submission package. It's worth asking the manufacturer ofMPB22 switch.E-switch products look the same and of course much more expensive, but they have electrical safety approvals.I would just run yourself into the ground as far as questions and then book the technical consultation with the agency, nail them with questions to get the best value for the session dollars/minutes.It takes quite a while to learn how to interpret safety standard clauses and to learn the traps with getting something certified.

author: jonpaul
author_rank: Super Contributor
timestamp: June 13, 2022, 02:43:31 pm
content: regarding insulation vs temperature, there's an exponentially related change in resistance per volume, besides any effect of humidityCheck the materials specifics, eg G-10 fiberglass, bakélite, teflon.High voltage testing worse case is at high not low temperatureJon

author: paulcolemonster
author_rank: Newbie
timestamp: June 13, 2022, 07:34:41 pm
content: Thanks for all of your suggestions and comments - they have all been very helpful, especially regarding seeking component level approvals for mains carrying parts, and of finding a consultant.@jonpaul - That makes sense when you think about it - things tend to melt / burn / deform / degrade with heat. I was fixated on the effects of moisture, which is typically driven off by heat. I'm a marine engineer by profession, where low insulation problems tend to be caused by seawater being where it shouldn't and tend to fixed with a bit of warmth!@floobydust - the spaghetti comment resonates.Are there any decent companion textbooks to the standards? I will be looking for a consultant but still need to understand, especially as it'll be my name on the DOC.

author: floobydust
author_rank: Super Contributor
timestamp: June 14, 2022, 11:15:57 pm
content: There's no educational material, books etc. about product development and electrical safety standards out there, that I have ever seen. There could be...First, it's a monopoly on that knowledge the certification bodies need to keep to themselves for maximum profit. Internally, they have their own little "university" to train their certifiers. Junior certifiers have access to senior people for when they get stuck or not sure about it.Second, there is always a perceived big, scary liability. It was hilarious working with botched certifications, UL included, their only liability is for you to "remove the label" and give a discount/refund towards a re-certification. They can't be sued if unsafe product rolls out due to their mistake.You'll note the agencies won't give instructions or guidance because they can't - it would betray other clients by sharing how other companies did it. It's all very subtle and creates great waste in that every client must re-invent the wheel and lab test the same stuff.Always confirm an agency is accredited to the standard that you need certification to, the "cheapo" certification agencies are usually charlatans and will give a real deal despite not having the test equipment or accreditation for the work. Been through that as well.A consultant or EEVblog guy sticking his neck out, giving direction, if they're wrong it causes too much drama. Trolls have a good time, people can be assholes about safety yet "muh I'm right!" is secondary to the task at hand. So people keep quiet about it and just refer to getting a paid consult at an agency.Any book would get lambasted I think.

author: jonpaul
author_rank: Super Contributor
timestamp: June 15, 2022, 06:02:26 am
content: bonjour à Floob et Paul Cole.As EE and consultants in SMPS, HV, medical electronic, in 1970s..1990s, we often fixed safety, EMI, transients issues for compliance.Firms and consultants exist to interface with the standards and Laboratoires.We recall Complice Design in Boston area, who also published a magazine.Those who advise must have liability and E&O ( errors and omissions) insurance.As a note, about .1993, a 1 kW medical power supply for arc lamp illuminators took 1 yr to design and one year for compliance and approval.For books, many existe for EMI, transients, high voltage.I am certain that a deeper search for old textbooks can discover a fine reference for such complice design.besides UL, the alternatives, ETL, TUV, VDE and other testing laboratoires are available in most areas.finally expect to pay a significant fee for consulting services or laboratory to get products compliance.Bon courageJonjust the ramblings of an old retired EE