Re: Safety: Hi-Pot Suppression for TNV lines
Chris, The standard (UL1950/EN 60 950) allows you to conduct an Impulse Test in lieu of a Dielectric Strength Test. The MOVS should be left in place when doing an Impulse Test. Most probably you will pass using the Impulse Test Method and you do not need to spend money on re-work or perpheral devices. Your only problem is Australia which requires passing both a Dielectric Strength and Impulse Test, both at a slightly higher voltage than the EN 60 950/UL1950 standards. Best Regards At 10:33 22/05/2000 -0400, Maxwell, Chris wrote: Group, Is there an in-line adapter that we can install on a TNV line (in our case, a typical RJ12 phone line) to our product that will provide a second layer of hi-pot protection? The whole explanation follows for those who think they can help. Others can press delete right now and get on with their day. We produce a piece of fiber optic test equipment that is rack mounted and operates from 48VDC. Most of our typical equipment does not have TNV connections, however this does. We have designed a remote reset option. The remote reset consists of an RJ12 jack on the back of the unit. The user can plug a phone line into this jack. Once installed, the user can perform a 5 second power down on the unit by dialing the unit's phone number and letting the line ring 5 times. This has proved valuable to customers because the units are designed for remote installation. If the unit hangs up, they don't have to drive, fly, hike or swim out to where the unit is installed to perform a hard re-boot. This remote reset line only takes in the TIP and RING signals (the RJ12 only has pins 3 and 4 populated). Both TIP and RING have MOV's going to chassis ground. We have had the unit safety tested. During safety testing, the MOV's were cut (creating a single fault condition). When the MOV's were cut, the hipot test caused an arc to ground on a circuitboard within the unit. This arc was considered a failure. My guess is that the arc is caused by the fact that the tip and ring signals run close to a piece of the ground plane on the top layer of the board. My first stab at fixing this would be to clear out the ground plane so that it is furthur away from tip and ring. Now, even minor changes to circuitboards can cost thousands. It can also mean scrap. This unit is a very low volume product (hundreds annually). It may be more cost effective for us to add some sort of in-line suppressor external to the unit as opposed to revising the circuitboard. Given that the unit is rack mounted, I am assuming that there would be room in the rack to mount such a device, if it existed. Hence my question. Anybody have any ideas? Thank you for your time. Chris Maxwell, Design Engineer GN Nettest Optical Division 109 N. Genesee St. Utica, NY 13502 PH: 315-797-4449 FAX: 315-797-8024 EMAIL: chr...@gnlp.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Safety: Hi-Pot Suppression for TNV lines
Chris, Have you considered spray-on conformal coating in the telco area? Tech Spray SR is one option that is also UL Recognized. Best Regards, Jody Leber jle...@ustech-lab.com http://www.ustech-lab.com U. S. Technologies 3505 Francis Circle Alpharetta, GA 30004 770.740.0717 Fax: 770.740.1508 -Original Message- From: Maxwell, Chris [SMTP:chr...@gnlp.com] Sent: Monday, May 22, 2000 10:34 AM To: 'EMC-PSTC Internet Forum' Subject:Safety: Hi-Pot Suppression for TNV lines Group, Is there an in-line adapter that we can install on a TNV line (in our case, a typical RJ12 phone line) to our product that will provide a second layer of hi-pot protection? The whole explanation follows for those who think they can help. Others can press delete right now and get on with their day. We produce a piece of fiber optic test equipment that is rack mounted and operates from 48VDC. Most of our typical equipment does not have TNV connections, however this does. We have designed a remote reset option. The remote reset consists of an RJ12 jack on the back of the unit. The user can plug a phone line into this jack. Once installed, the user can perform a 5 second power down on the unit by dialing the unit's phone number and letting the line ring 5 times. This has proved valuable to customers because the units are designed for remote installation. If the unit hangs up, they don't have to drive, fly, hike or swim out to where the unit is installed to perform a hard re-boot. This remote reset line only takes in the TIP and RING signals (the RJ12 only has pins 3 and 4 populated). Both TIP and RING have MOV's going to chassis ground. We have had the unit safety tested. During safety testing, the MOV's were cut (creating a single fault condition). When the MOV's were cut, the hipot test caused an arc to ground on a circuitboard within the unit. This arc was considered a failure. My guess is that the arc is caused by the fact that the tip and ring signals run close to a piece of the ground plane on the top layer of the board. My first stab at fixing this would be to clear out the ground plane so that it is furthur away from tip and ring. Now, even minor changes to circuitboards can cost thousands. It can also mean scrap. This unit is a very low volume product (hundreds annually). It may be more cost effective for us to add some sort of in-line suppressor external to the unit as opposed to revising the circuitboard. Given that the unit is rack mounted, I am assuming that there would be room in the rack to mount such a device, if it existed. Hence my question. Anybody have any ideas? Thank you for your time. Chris Maxwell, Design Engineer GN Nettest Optical Division 109 N. Genesee St. Utica, NY 13502 PH: 315-797-4449 FAX: 315-797-8024 EMAIL: chr...@gnlp.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Safety: Hi-Pot Suppression for TNV lines
Chris, Clear away the ground plane to give you the proper clearance. You need to be able to pass the tests without an external protector. You didn't mention Part 68 in your message. You do need that as well, plus an FCC Registration Number (although what you have to do to file for it may be changing very soon), manual verbiage, etc. If all else fails, you could supply a remote modem switch that would control power to your product. There are a few manufacturers but they can be a little pricey. Dave Spencer Oresis Communications -Original Message- From: Eric Petitpierre [mailto:eric.petitpie...@pulse.com] Sent: Monday, May 22, 2000 10:14 AM To: emc-p...@majordomo.ieee.org; Maxwell; Chris Subject: Re: Safety: Hi-Pot Suppression for TNV lines Chris, Usually the hi-pot tests done during the safety evaluation are meant to verify spacings and insulation. The hi-pot tests I have seen usually allow intentional paths to ground to be disconnected. It is the trace separation,etc, you are interested in, not how well the MOV conducts. Both MOV's are considered intentional paths to ground. Both should to be disconnected at the ground side during the test. If only one is disconnected, you may still have a path, whether it is direct, or through the contacts (open or closed) of the hookswitch. Eric Petitpierre Pulsecom Herndon, VA eric.petitpie...@pulse.com __ Reply Separator _ Subject: Safety: Hi-Pot Suppression for TNV lines Author: chr...@gnlp.com (Maxwell; Chris) at smtp List-Post: emc-pstc@listserv.ieee.org Date:5/22/00 10:33 AM Group, Is there an in-line adapter that we can install on a TNV line (in our case, a typical RJ12 phone line) to our product that will provide a second layer of hi-pot protection? The whole explanation follows for those who think they can help. Others can press delete right now and get on with their day. We produce a piece of fiber optic test equipment that is rack mounted and operates from 48VDC. Most of our typical equipment does not have TNV connections, however this does. We have designed a remote reset option. The remote reset consists of an RJ12 jack on the back of the unit. The user can plug a phone line into this jack. Once installed, the user can perform a 5 second power down on the unit by dialing the unit's phone number and letting the line ring 5 times. This has proved valuable to customers because the units are designed for remote installation. If the unit hangs up, they don't have to drive, fly, hike or swim out to where the unit is installed to perform a hard re-boot. This remote reset line only takes in the TIP and RING signals (the RJ12 only has pins 3 and 4 populated). Both TIP and RING have MOV's going to chassis ground. We have had the unit safety tested. During safety testing, the MOV's were cut (creating a single fault condition). When the MOV's were cut, the hipot test caused an arc to ground on a circuitboard within the unit. This arc was considered a failure. My guess is that the arc is caused by the fact that the tip and ring signals run close to a piece of the ground plane on the top layer of the board. My first stab at fixing this would be to clear out the ground plane so that it is furthur away from tip and ring. Now, even minor changes to circuitboards can cost thousands. It can also mean scrap. This unit is a very low volume product (hundreds annually). It may be more cost effective for us to add some sort of in-line suppressor external to the unit as opposed to revising the circuitboard. Given that the unit is rack mounted, I am assuming that there would be room in the rack to mount such a device, if it existed. Hence my question. Anybody have any ideas? Thank you for your time. Chris Maxwell, Design Engineer GN Nettest Optical Division 109 N. Genesee St. Utica, NY 13502 PH: 315-797-4449 FAX: 315-797-8024 EMAIL: chr...@gnlp.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher
Re: Safety: Hi-Pot Suppression for TNV lines
Chris, Usually the hi-pot tests done during the safety evaluation are meant to verify spacings and insulation. The hi-pot tests I have seen usually allow intentional paths to ground to be disconnected. It is the trace separation,etc, you are interested in, not how well the MOV conducts. Both MOV's are considered intentional paths to ground. Both should to be disconnected at the ground side during the test. If only one is disconnected, you may still have a path, whether it is direct, or through the contacts (open or closed) of the hookswitch. Eric Petitpierre Pulsecom Herndon, VA eric.petitpie...@pulse.com __ Reply Separator _ Subject: Safety: Hi-Pot Suppression for TNV lines Author: chr...@gnlp.com (Maxwell; Chris) at smtp List-Post: emc-pstc@listserv.ieee.org Date:5/22/00 10:33 AM Group, Is there an in-line adapter that we can install on a TNV line (in our case, a typical RJ12 phone line) to our product that will provide a second layer of hi-pot protection? The whole explanation follows for those who think they can help. Others can press delete right now and get on with their day. We produce a piece of fiber optic test equipment that is rack mounted and operates from 48VDC. Most of our typical equipment does not have TNV connections, however this does. We have designed a remote reset option. The remote reset consists of an RJ12 jack on the back of the unit. The user can plug a phone line into this jack. Once installed, the user can perform a 5 second power down on the unit by dialing the unit's phone number and letting the line ring 5 times. This has proved valuable to customers because the units are designed for remote installation. If the unit hangs up, they don't have to drive, fly, hike or swim out to where the unit is installed to perform a hard re-boot. This remote reset line only takes in the TIP and RING signals (the RJ12 only has pins 3 and 4 populated). Both TIP and RING have MOV's going to chassis ground. We have had the unit safety tested. During safety testing, the MOV's were cut (creating a single fault condition). When the MOV's were cut, the hipot test caused an arc to ground on a circuitboard within the unit. This arc was considered a failure. My guess is that the arc is caused by the fact that the tip and ring signals run close to a piece of the ground plane on the top layer of the board. My first stab at fixing this would be to clear out the ground plane so that it is furthur away from tip and ring. Now, even minor changes to circuitboards can cost thousands. It can also mean scrap. This unit is a very low volume product (hundreds annually). It may be more cost effective for us to add some sort of in-line suppressor external to the unit as opposed to revising the circuitboard. Given that the unit is rack mounted, I am assuming that there would be room in the rack to mount such a device, if it existed. Hence my question. Anybody have any ideas? Thank you for your time. Chris Maxwell, Design Engineer GN Nettest Optical Division 109 N. Genesee St. Utica, NY 13502 PH: 315-797-4449 FAX: 315-797-8024 EMAIL: chr...@gnlp.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
