Re: [PSES] Low current Transformer OC Protection

Hello Experts, In a previous life I spent quite a bit of time testing power-limited small transformers to North American requirements. One of the design strategies I encountered was the use of a special nylon coated wire(NEW), which would open safely and repeat-ably under fault conditions at a

Re: [PSES] Low current Transformer OC Protection

Transformers that "don't need a fuse" need an 'inherently limited' assessment per UL5085-3/CSA No.66.3 and/or IEC61558-2-6. Limits based on load current are correct where NEC article 725 is scoped, as it becomes a wiring issue. For North America, the limits would be defined in CSA No.223 and

Re: [PSES] Measurement Uncertainty Above 18 GHz

In the field of compliance, we are not looking so much for an accurate measurement (where measurement uncertainty would be important), but rather to determine if the equipment is under the limit. Most of the time, the equipment should be comfortably under the limit so that uncertainty of

Re: [PSES] 2nd hand or refurbished products

Dave, et al, That is true the product MAY NOT comply (but it MAY) with the current requirements when it is imported into the EU but that is now easily checked by reference to the details in the Technical File. The product owner may then decide as to the

Re: [PSES] Low current Transformer OC Protection

Hi Brian: It sounds to me as though you have an “impedance-protected” transformer. A common example in the USA is a doorbell transformer. The output can be shorted all day, and the transformer will not overheat (exceed the insulation temperature ratings). The transformer cannot

Re: [PSES] Low current Transformer OC Protection

Limits based on load current may well be what the NEC requires, but that doesn't make it technically correct. When is Ohm's Law suspended so that the worst-case inrush current isn't volts/ohms? With best wishes DESIGN IT IN! OOO – Own Opinions Only www.jmwa.demon.co.uk J M Woodgate and

Re: [PSES] 2nd hand or refurbished products

But the requirements for the CE mark are that it meet the EU directives in force at the time it’s placed into market in the EU, not based on date of manufacture? So a 15 year old CE marked product may still not comply with current EU directives at the time it’s imported. -Dave From: Pete

Re: [PSES] Low current Transformer OC Protection

If the transformer is a 'certified' component, what are its ratings and conditions of acceptability? Do the connected circuits in the end-use equipment have a required interrupt rating? What article of the code is being applied? Per admin law, Field assessment only done by a NRTL or AHJ. Any

Re: [PSES] Low current Transformer OC Protection

John, One transformer I’m currently looking at has the following specs: Input = 80-300V (230V Nom) 50/60hz Output = (@ 230V input) 2 x 5.0V @ 0.0025A Output Power = 0.025 VA Insulation Class “F” (155ºC). I don’t currently have a sample transformer to measure the primary impedance. It would be

Re: [PSES] 2nd hand or refurbished products

Scott, Some users of large process equipment know that the equipment will be repositioned within its useful lifetime anywhere on the globe. They insist on the original equipment having all of the ‘certification pedigrees’ for such use. This means that the equipment will,

Re: [PSES] Low current Transformer OC Protection

This is why small transformers that don't need a fuse were developed. They have a special type of coated wire for the primary winding, which goes quietly open-circuit if it gets too hot. However, I suppose your product standard might not allow them. The limits based on load current are

[PSES] CE Marking on Inkjet Cartridge

All - It is my understanding that an inkjet cartridge that contains an electronic chip is considered EEE and is therefore subject to RoHS and WEEE (and of course REACH). 1. Is my statement above regarding RoHS/WEEE correct? 2. Is it also considered "apparatus" under the EMC Directive? I'm

[PSES] Low current Transformer OC Protection

Greeting Experts. I often run into issues with safety inspectors during Field Evaluations regarding overcurrent protection of small transformers that are not thermally protected. These small transformers can draw such small amounts of current on both the primary and secondary, that finding a

Re: [PSES] Measurement Uncertainty Above 18 GHz

Good point. They are Technical Specifications rather than full standards, but they are free downloads form the ETSI site. With best wishes DESIGN IT IN! OOO – Own Opinions Only www.jmwa.demon.co.uk J M Woodgate and Associates Rayleigh England Sylvae in

Re: [PSES] Measurement Uncertainty Above 18 GHz

Grace, There are ETSI standards such as TS 103 051 that addresses MU up to 100 GHz and TS 103 052 which addresses radiated measurement sites up to 100 GHz. Larry K. Stillings Compliance Worldwide, Inc. Test Locally, Sell Globally and Launch Your Products Around the World! FCC - Wireless

Re: [PSES] 2nd hand or refurbished products

Nick, Both situations are very rare in reality due to EU rule. In the EU market, probably all the second hand products are largely restricted within the EU since any second hand products outside EU may not meet the latest requirements. Regards, Scott From: Nick

Re: [PSES] 2nd hand or refurbished products

Scott, Many second-hand products will have difficulty meeting current requirements. This is a problem for products which have been used outside the EU when they are imported into the EU for the first time, but for second hand products which are already within the EU (i.e. those which were