Re: Fw: working voltage measurement

2001-12-31 Thread Cortland Richmond
Yes, it's important to recognize the limitations of a test method before relying on it. In this case, the A-B method was used at power frequency and below, to observe discharge time for UL testing. The MAIN advantage was not balance so much as that the chassis was isolated from the potential being

RE: Fw: working voltage measurement

2001-12-31 Thread Gregg Kervill
Just to add to what Rich has stated - the CMRR will also vary with frequency for both passive and active systems. These variation are caused by small differences in the LCR coupling of the probes and the finite bandwidth of any amplifier. I remember using a very high gain product (A Thermal Ima

Re: EMC-related safety issues

2001-12-31 Thread John Woodgate
I read in !emc-pstc that cherryclo...@aol.com wrote (in <17c.18c06c2.296 20...@aol.com>) about 'EMC-related safety issues', on Mon, 31 Dec 2001: >Quite a number of EMC and Safety experts took part in creating the IEE's >Guide on EMC and Functional Safety, including a lawyer who specialis

Fw: question on emc and networks

2001-12-31 Thread Robert Macy
I offered to forward this to the emc group for help. Please answer directly. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA

Re: EMC-related safety issues

2001-12-31 Thread Ken Javor
In a court of law one must swear to tell the truth, the whole truth, and nothing but the truth. What you stated below is merely part of the truth. The rest of the truth is that spurious emissions emitted by unintentional radiators (the kinds of emissions controlled by CISPR 22 and Title 47, part

Re: Fw: working voltage measurement

2001-12-31 Thread Rich Nute
Hi Cortland: > One can also use a pair of probes known to be well balanced and take the > difference between the A and B channels, or > use a differential input accessory or plugin. There is then no possibility > of high-voltage on the instrument chassis. "Balance" is really Common-Mod

Re: EMC-related safety issues

2001-12-31 Thread CherryClough
Dear Ken Any electromagnetic emissions, whether conducted or radiated, including spurious emissions (however you wish to define the word 'spurious') can be demodulated by the non-linear processes in semiconductors, vacuum tubes, and the like. So the spread of possible problems goes beyond merely

Re: EMC-related safety issues

2001-12-31 Thread CherryClough
Dear John Quite a number of EMC and Safety experts took part in creating the IEE's Guide on EMC and Functional Safety, including a lawyer who specialises in high-tech issues. You will find their names listed at the end of the 'core' of the guide (downloadable from www.iee.org.uk/Policy/Areas/Ele

Re: Fw: working voltage measurement

2001-12-31 Thread Rich Nute
Hi Xing Weibing: > 2. supply the SMPS from an isolating transformer where > both supply conductors are isolated from ground. > 3. connect secondary's ground and primary 's ground (neutral and ground > are connected together) This is the correct connection for measuring the prim

Re: EMC-related safety issues

2001-12-31 Thread John Woodgate
I read in !emc-pstc that cherryclo...@aol.com wrote (in <123.96b6ec6.296 1b...@aol.com>) about 'EMC-related safety issues', on Mon, 31 Dec 2001: >(A key member of the IEC 61000-1-2 committee is a very senior safety > expert >and also a key member of the IEE Working Group that created thi

Re: EMC-related safety issues

2001-12-31 Thread Ken Javor
All of this message is very interesting and I have no problem with it at all. That doesn't change the fact that, as I and others stated earlier, there is no intrinsic safety issue with a spurious emission. Spurious emissions only affect the ability to receive a radio signal. That was and is the

EMC-related safety issues

2001-12-31 Thread CherryClough
Dear all There was a discussion about electromagnetic emissions and safety issues a couple of weeks ago which I only caught the tail end of, so I hope my comments below are relevant and useful. I would also like to make a plea for assistance. Spurious emissions and safety. Even if we ignore 'le