Re: voltage on Neutral line, Measurements From Chile
At 12:08 AM 6/29/99 -0700, mvald...@netvision.net.il wrote: Hello everyone, What voltages can I expect on the Neutral (referenced to ground) line in various countries and connection systems? Is there a limit on how high the voltage may be, both in normal and fault conditions? Some of our Cellular base stations are located in regions of Chile where power is being intentionally turned off due to low water conditions at hydro-electric plants. We have been montoring the voltage at these sites due to concerns about the battery backup system. The cell sites use 380V Line to Line, 220V Line to Neutral, 3-Phase power. During restoration of power, the voltage on neutral sometimes rises to 220V Line to Ground for several cycles. The voltage on the phases has been measured as great as 440V Line to Line for several cycles, with Line to Neutral voltages as high as 380V. There does not seem to be much power available during this transition time with the wild voltages. Preliminary measurements in Brazil are showing some of the same results. The load regulation at remote sites seems to be a problem. Don Kimball thanks in advance, Moshe Name: moshe valdman E-mail: mvald...@netvision.net.il Phone: 972-54-881334 Telefax: 972-3-5496369 Date: 29/6/99 Time: 0:08:41 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Transmitter Type Acceptance, Peru Dominican Republic, Cell Phones
What are the Peruvian and Dominican Republic transmitter type acceptance regulatory requirements? Do they rely on the FCC ID number? If a cell phone does not yet have an FCC ID number, is there an Peruvian or Dominican ID number that is required? I am experiencing some delays with the Type Acceptance process in the United States, but we have some ready customers in Peru and the Dominican Republic. I am trying to explore my options. Thank You, Don Kimball - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Xenon Short Arc Lamp, Theatre Movie Projector, EMC Issues?
I am working on a project where some digitial signal processing electronics will reside inside of a digital movie projector for a large theatre. The digital projector does not use film. The projector will contain a Xenon Short Arc Lamp of up to 7kW. The ignition voltage for the lamp is 25-30kV. What are the significant EMC issues for such an environment? I am concerned about emissions from the power supply (i.e. ballast) used for the lamp, and susceptibility of the digital signal processor. I am trying to locate information on both the expected transient voltage and current waveform through the lamp, and the expected steady state voltage and current waveform through the lamp. Don Kimball - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: 1000Base-T (IEEE 802.3ab) vs. EMI on UTP (Unshielded Twisted Pairs)
At 10:55 AM 12/10/98 -0500, Jon D. Curtis wrote: According to an artical by Lee Goldberg in Electronic Design November 16, 1998, Giga bit ethernet usesPAM-5 modulation scheme with a partial-response spectrum shaping of the form 0.75 + 0.25z(-1) to limit emissions to within the FCC limits. I read that same article. The spectral density does fall below 100BaseT, but only when you shift the spectrums so that the fundamental frequencies line up. Remember, the Z-Transform produces only a relative frequency response. You have to plug in the actual sampling rate to get the absolute frequency response. When the absolute frequency spectrum in used, the 1000Base-T spectral density around 125MHz is much higher than the spectral density of 100Base-T at 125MHz. This simple filter shapes the spectrum so that its power spectral density falls below that of existing 100Bast T ethernet. Since 100BaseT is compliant, it is likely that Gigabit will be compliant. The magic is in the spreading algorithim which spreads the energy uniformly over a very broad range while maintaining the bipolar average. I did not see sufficient details in this article about the spreading algorithm. For example, if a bunch of consecutive 1's are transmitted, I am not sure how many consecutive symbols are randomized before the pattern repeats. It could be virtually infinite (i.e. what is PN^(n)). They are also using the redundant symbols to improve the signal to noise ratio by 6dB. The energy must be uniformally spread from ?kHz to 125MHz, otherwise the comment about the Z-Transform filter does not make any sense. Don Kimball As far as I know, all ethernet standards incorporate these modulation schemes in order to comply when transmitted over unshielded cables. Since emissions are measured with a 120kHz bandwidth (from 30-1000MHz), you can pump out a lot of power if you spread it over a large frequency (say 100MHz). If the other end is intellegent enough to decode your scrambled bits, and you code for emissions reduction/spreading the result is communications at a high rate with emissions in compliance with the FCC limits. Donald Kimball wrote: The IEEE 802.3ab defines the new Gigabit Ethernet Standard (i.e. 1000Base-T). This Local Area Network (LAN) can use 4 twisted pairs of unshielded copper cable (Category-5) at 100m maximum operating at 250Mb/s per pair in full-duplex bi-directional mode. This standard is designed to utilize existing LAN cables such as older 10Base-T and 100Base-T networks. The signaling (i.e. baud) rate is 125MHz per pair using 5-level Pulse Amplitude Modulation (PAM) . This probably results in the fundmental energy at 62.5MHz given that the signal must be bipolar to be compatible with transformers. Vendors such as Broadcom Corp. have developed single chip copper cable interfaces for this new standard. In the past, standards using unshielded cables, such as 100Base-T, 10Base-T, T1, E1, etc, have had signaling rates less than 30MHz, so that the fundamental frequency was below the 30MHz FCC and CISPR starting frequency for radiated emissions. However, 1000Base-T has a 125MHz signaling rate. A common mode current of less than 10uA at 30MHz at 1/2 of wavelength can yield an emission level equal to or greater than the Class B level. In addition, the 4 twisted pairs are all phase locked to each other. The intentional differential mode current is about 10mA, so the trans hybrid balance needs to be better than 60dB. This is achievable with the hybrid at the component level, but not at the system level with 100m of Cat 5 cable attached. Conclusion, I think that 1000Base-T (IEEE 802.3ab) on unshielded Category 5 cable is doomed to fail EMI. Anybody ever try a test? Any other opinions? Don Kimball - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). -- Jon D. Curtis, PE Curtis-Straus LLC j...@curtis-straus.com Laboratory for EMC, Safety, NEBS, SEMI-S2 and Telecom 527 Great Roadvoice (978) 486-8880 Littleton, MA 01460 fax (978) 486-8828 http://www.curtis-straus.com - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j
1000Base-T (IEEE 802.3ab) vs. EMI on UTP (Unshielded Twisted Pairs)
The IEEE 802.3ab defines the new Gigabit Ethernet Standard (i.e. 1000Base-T). This Local Area Network (LAN) can use 4 twisted pairs of unshielded copper cable (Category-5) at 100m maximum operating at 250Mb/s per pair in full-duplex bi-directional mode. This standard is designed to utilize existing LAN cables such as older 10Base-T and 100Base-T networks. The signaling (i.e. baud) rate is 125MHz per pair using 5-level Pulse Amplitude Modulation (PAM) . This probably results in the fundmental energy at 62.5MHz given that the signal must be bipolar to be compatible with transformers. Vendors such as Broadcom Corp. have developed single chip copper cable interfaces for this new standard. In the past, standards using unshielded cables, such as 100Base-T, 10Base-T, T1, E1, etc, have had signaling rates less than 30MHz, so that the fundamental frequency was below the 30MHz FCC and CISPR starting frequency for radiated emissions. However, 1000Base-T has a 125MHz signaling rate. A common mode current of less than 10uA at 30MHz at 1/2 of wavelength can yield an emission level equal to or greater than the Class B level. In addition, the 4 twisted pairs are all phase locked to each other. The intentional differential mode current is about 10mA, so the trans hybrid balance needs to be better than 60dB. This is achievable with the hybrid at the component level, but not at the system level with 100m of Cat 5 cable attached. Conclusion, I think that 1000Base-T (IEEE 802.3ab) on unshielded Category 5 cable is doomed to fail EMI. Anybody ever try a test? Any other opinions? Don Kimball - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
EMC Standards for Brazil?
I am trying to find the EMC standards for Brazil. Here are the Telebras standards I think I need: 1) NBR 12304 2) NBR 320225 I think these standards are in Portuguese, but I would prefer an English translation. Don Kimball - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
EN 55022 vs. Telecommunications -48Vdc DC Powered Equipment, Conducted Emissions AC side or DC side?
I work for Qualcomm, and we EMC test -48Vdc powered telecommunications equipment, especially cellular and PCS base stations. The -48Vdc power is usually shared with other equipment at the same location (eg. an Alcatel Switch, Cisco Router, etc.) We have always tested for conducted emissions on DC side of the power line, since we do not control the AC to DC power converter, and we share the DC power with other equipment. Recently, we integrated another vendor's E1 inverse multiplexer into our base station controller racks. The vendor claimed CE mark compliance and sent us a test report. This equipment is powered by -48Vdc, but they tested for conducted emissions on the AC side of the AC to DC power supply that powered the E1 inverse multiplexer. When questioned, they said that the test facility told them they must test on the AC side of the line, and not the DC side of the line. The test facility said they would not issue a declaration of conformity based on testing the DC side of the power line. In fact, they went through several AC to DC power supplies before they found a power supply that was EN 55022 compliant by itself. This makes no sense, since the DC power is shared, and the choice of AC to DC power supply cannot be controlled by Qualcomm. Moreover, a well chosen AC to DC power supply can filter out the noise on the DC side of the line. In fact, one version of the inverse multiplexer fails on the DC side of the power line, but passes on the AC side of the line. If the emissions on the DC side of the power line are compliant with EN 55022 Class A limits, the those same emissions should be below the limit on the AC side. What is the correct answer in this case? Do you test the AC side or the DC side? Don Kimball - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
