A ROM (rough order of magnitude) estimate of magnetic radiation from power lines at 1 km yields a very small magnetic field. I used H = I/(6.28*r) with I = V/R and r = 1 km. I assumed V = 1 Volt and R = 100 Ohms to yield an I = 10 mA. Then H is on the order of 1 uA/m , very close to 1 pT which is well below the threshold of sensitivity of the ADF radio connected to the ADF loop.
---------- >From: Mike Hopkins <[email protected]> >To: "'Ken Javor'" <[email protected]>, [email protected], [email protected] >Subject: RE: Company close down due to EMC phenomena >Date: Thu, Jan 17, 2002, 12:25 PM > > > Although there is no AM broadcast below 530kHz, there are still many > services using the frequencies between 200kHz and 530kHz, the most important > of which is the aviation industry. Called NDB's, these low frequency signals > are still used for navigation globally and instrument approaches in airports > world-wide. > >>From a vantage point several thousand feet above the local power lines, a > 25ms burst once/hour would be no big deal, but if there are lots of 25ms > bursts/hour in a given area, this could be a problem! > > Mike Hopkins > Thermo KeyTek > (pilot of small airplane who does not want the ADF needle going around in > circles -- especially when in use by pilot trying to figure out which way's > home) > > > > -----Original Message----- > From: Ken Javor [mailto:[email protected]] > Sent: Wednesday, January 16, 2002 4:53 PM > To: [email protected]; [email protected] > Subject: Re: Company close down due to EMC phenomena > > > > A technical response from an American. I sympathize with the viewpoint that > the duty cycle is very low and the on-time is very low and the potential for > mischief is near nil. I would add a further argument. 55022 CE limits > protect AM radio reception. In the USA there is no AM broadcast below 530 > kHz. In the EU there is some LW broadcasting from I believe 150 - 300 kHz, > and then MW picks up again at 530 kHz. So the potential for rfi is limited. > That "officials" would even consider banning such a product is an argument > against anyone having such power. > > ---------- >>From: <[email protected]> >>To: <[email protected]> >>Subject: Company close down due to EMC phenomena >>Date: Wed, Jan 16, 2002, 2:17 PM >> > >> >> Well, this might be the reality in a case I have been introduced to > lately. >> >> Case: >> A company are manufacturing PowerLine Communication products. They >> communicate via the power lines and a typical link is between a consumer >> residence and the nearest power station. The products can of course also >> communicate inside the consumers residence. The communication protocol is >> called CEBus http://www.cebus.org/which and make use of the frequency band >> 100kHz-400kHz and the amplitude is approximate 2-5V. A typical length of a >> transmission is 25ms and occurs approximate one time pr hour. >> >> First of all, AFAIK PowerLine Communication and PowerLine Transmission >> (broadband 1.6MHz-30MHz) are now coming will full force in EU and >> CENELEC/ETSI are working together regulate this type of transmission path >> and also coming up with standards. >> >> The problem for the manufacturer is the conducted emission requirements in >> EU. According to the EN55022B levels the maximum quasi-peak emission is >> 66dBuV@150kHz, and a typical PLC (under transmission) which has been >> measured, showed the value of 120dBuV (peak). With no transmission it had > a >> margin of 10dB (quasi-peak) and 30dB (average). The radiated emission had > a >> margin of 10dB. >> >> Well, conducted emission is the problem when transmitting. But, as I said, >> the transmission occurs only 25ms/hour. >> >> The national authority will not allowed this product to be placed into the >> marked because it do not fulfil the EN55022B limits (100kHz-400kHz) under >> transmission mode. No way. >> >> Other national authorities have other approaches on this case, they say " > as >> long as you do not disturb other equipment, install it. If you do disturb, >> we will come and remove it". They also say " install it even if it does > not >> fulfil EN550022B, but we will remove it if it disturb others". >> >> Two completely different approaches as you see. >> >> Questions: >> 1. Is it possible to have different approaches within EU ? >> 2. Since PLC/PLT is "quite new" technology and since we do not have any EU >> product standard (no standard for whose who are using 100kHz-400kHz band), > I >> like the approach "as long as you do not disturb other equipment, install >> it. If you do disturb, we will come and remove it". What is your opinion >> about this? >> 3. The transmission occurs very seldom. 25ms/hour, that is 7e-6 and >> approximate 0,001% transmission rate. Can this seldom transmission rate be >> an argument to not test the PLC product under continuous transmission ? I >> would say yes, but which rate is acceptable / reasonable ? >> >> So, why should the company close down ? Because if the national authority >> gets what they want, there will be one sale. Logical, but is it a correct >> prohibition the authority call? >> >> >> Best regards >> Amund Westin, Oslo/Norway >> >> >> >> >> >> >> >> ------------------------------------------- >> This message is from the IEEE EMC Society Product Safety >> Technical Committee emc-pstc discussion list. >> >> Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ >> >> To cancel your subscription, send mail to: >> [email protected] >> with the single line: >> unsubscribe emc-pstc >> >> For help, send mail to the list administrators: >> Michael Garretson: [email protected] >> Dave Heald [email protected] >> >> For policy questions, send mail to: >> Richard Nute: [email protected] >> Jim Bacher: [email protected] >> >> All emc-pstc postings are archived and searchable on the web at: >> No longer online until our new server is brought online and the old >> messages are imported into the new server. >> > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > [email protected] > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson: [email protected] > Dave Heald [email protected] > > For policy questions, send mail to: > Richard Nute: [email protected] > Jim Bacher: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > No longer online until our new server is brought online and the old > messages are imported into the new server. > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
