Re: UL 60950, Section 6.1.2.1
Hi Doug: A question. If you bridge the barrier between TNV and earth, for the purposes of test 6A, I assume the test voltage is the upper limit of the rated mains voltage of the equipment, (240V). Is this correct? According to 6.1.2.1, the test voltage is either: - the rated voltage of the equipment, or - the upper limit of the rated voltage range. If you rate the equipment 240 V, then the test voltage is 240 V. If you rate the equipment 230 V, +-10%, then the test volage is 253 V. If you rate the equipment 100-250 V, then the test voltage is 250 V. Best regards, Rich From douglas_beckw...@mitel.com Tue Jun 4 09:35:39 PDT 2002 Subject: Re: UL 60950, Section 6.1.2.1 To: Rich Nute ri...@sdd.hp.com Cc: rgeorger...@carrieraccess.com, emc-p...@majordomo.ieee.org Date: Tue, 4 Jun 2002 12:27:52 -0400 Hi Rich, A question. If you bridge the barrier between TNV and earth, for the purposes of test 6A, I assume the test voltage is the upper limit of the rated mains voltage of the equipment, (240V). Is this correct? Regards Doug Rich Nute ri...@sdd.hp.com@majordomo.ieee.org on 05/16/2002 05:30:25 PM Please respond to Rich Nute ri...@sdd.hp.com Sent by: owner-emc-p...@majordomo.ieee.org To: rgeorger...@carrieraccess.com cc: emc-p...@majordomo.ieee.org Subject: Re: UL 60950, Section 6.1.2.1 Hi Richard: For those who want to read the UL60950 Section 6.1.2.1, I have written the specific parts of the section that I have questions on. Otherwise, here are my questions and comments: 1) If the bridging components are left in place, do I still have to meet the 10 mA requirement? No. The standard is quite clear that the Figure 6A, 10 mA, test is only performed if components are removed for the electric strength test. Note the statement: If this option is chosen, an additional test... is performed with all components in place. 2) If so, at which test voltage, the 1.5kV/1.0kV or EUT's rated voltage/range? The test voltage is the EUT rated voltage, not the electric strength test voltage. The paragraph describing what to do if components are removed, implies that if the components are left in place, the 10 mA test is not performed, only that the components shall not be damaged. But the section describing the passing requiring requirements does not make that distinction. They are part of an 'and' condition. The standard implies that some circuits may have components connecedt between the telecom network and earth. For such circuits -the components could load the electric strength test such that the test would appear to be a failure, or -the test voltage could damage the components. Therefore, the standard allows such components to be removed such that only the insulation is tested (and the components are not damaged). However, the standard requires a degree of isolation between the telecom network and earth such that the impedance is not less than 7 kohms for a 120-V source (120 V/10 mA - 5 kohms). 3) If the 10 mA test is not required, when the bridging components are left in place, then what is the reasoning for having these components be able to exceed the 10 mA, when those components that had to be removed, be subject to the 10 mA max current? The problem is that the impedance will either load the hi-pot tester such that it indicates failure or cannot rise to the specified voltage (1 kV or 1.5 kV), or the component cannot withstand the hi-pot test voltage and is destroyed. For these reasons, the line-to-earth components can be lifted for the hi-pot test (1 kV or 1.5 kV), but must be tested by the rated voltage test (120 V or 230 V, 10 mA max). Imagine a non-linear voltage-limiting device between the network line and earth. At working voltages, the device appears as an open circuit. At higher voltages, the device appears as a relatively low impedance (or even near zero ohms). For the hi-pot test, the circuit would indicate failure because of the operation of the voltage-limiting device. For the rated-voltage/10 mA test, the device will appear as a relatively high impedance. In summary: The requirement is for basic insulation between the network line and earth. This insulation is tested by a hi-pot test. In some constructions, the circuit may have components (i.e., impedances) between line and earth. Depending on the components, the hi-pot test may not be possible, or may damage the line- to-earth components. In such cases, the components may
Re: UL 60950, Section 6.1.2.1
Hi Rich, A question. If you bridge the barrier between TNV and earth, for the purposes of test 6A, I assume the test voltage is the upper limit of the rated mains voltage of the equipment, (240V). Is this correct? Regards Doug Rich Nute ri...@sdd.hp.com@majordomo.ieee.org on 05/16/2002 05:30:25 PM Please respond to Rich Nute ri...@sdd.hp.com Sent by: owner-emc-p...@majordomo.ieee.org To: rgeorger...@carrieraccess.com cc: emc-p...@majordomo.ieee.org Subject: Re: UL 60950, Section 6.1.2.1 Hi Richard: For those who want to read the UL60950 Section 6.1.2.1, I have written the specific parts of the section that I have questions on. Otherwise, here are my questions and comments: 1) If the bridging components are left in place, do I still have to meet the 10 mA requirement? No. The standard is quite clear that the Figure 6A, 10 mA, test is only performed if components are removed for the electric strength test. Note the statement: If this option is chosen, an additional test... is performed with all components in place. 2) If so, at which test voltage, the 1.5kV/1.0kV or EUT's rated voltage/range? The test voltage is the EUT rated voltage, not the electric strength test voltage. The paragraph describing what to do if components are removed, implies that if the components are left in place, the 10 mA test is not performed, only that the components shall not be damaged. But the section describing the passing requiring requirements does not make that distinction. They are part of an 'and' condition. The standard implies that some circuits may have components connecedt between the telecom network and earth. For such circuits -the components could load the electric strength test such that the test would appear to be a failure, or -the test voltage could damage the components. Therefore, the standard allows such components to be removed such that only the insulation is tested (and the components are not damaged). However, the standard requires a degree of isolation between the telecom network and earth such that the impedance is not less than 7 kohms for a 120-V source (120 V/10 mA - 5 kohms). 3) If the 10 mA test is not required, when the bridging components are left in place, then what is the reasoning for having these components be able to exceed the 10 mA, when those components that had to be removed, be subject to the 10 mA max current? The problem is that the impedance will either load the hi-pot tester such that it indicates failure or cannot rise to the specified voltage (1 kV or 1.5 kV), or the component cannot withstand the hi-pot test voltage and is destroyed. For these reasons, the line-to-earth components can be lifted for the hi-pot test (1 kV or 1.5 kV), but must be tested by the rated voltage test (120 V or 230 V, 10 mA max). Imagine a non-linear voltage-limiting device between the network line and earth. At working voltages, the device appears as an open circuit. At higher voltages, the device appears as a relatively low impedance (or even near zero ohms). For the hi-pot test, the circuit would indicate failure because of the operation of the voltage-limiting device. For the rated-voltage/10 mA test, the device will appear as a relatively high impedance. In summary: The requirement is for basic insulation between the network line and earth. This insulation is tested by a hi-pot test. In some constructions, the circuit may have components (i.e., impedances) between line and earth. Depending on the components, the hi-pot test may not be possible, or may damage the line- to-earth components. In such cases, the components may be removed for the hi-pot test. However, the impedance of the components between line and earth cannot be less than that determined by the rated-voltage/10 mA test. If you have further questions, or want further clarification, please ask. Best regards, Rich --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http
RE: UL 60950, Section 6.1.2.1
Greetings All, Thanks to all to those who replied to my questions. I appreciate the time and effort that was put into the responses. Richard Georgerian Compliance Engineer Carrier Access Corporation 5395 Pearl Parkway Boulder, CO 80301 USA Tele: 303-218-5748 Fax: 303-218-5503 mailto:rgeorger...@carrieraccess.com * This e-mail transmission, and any documents, files, or previous e-mail messages attached to it may contain information that is confidential or legally privileged. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, you are hereby notified that you must not read this transmission and that any disclosure, copying, printing, distribution, or use of any of the information contained in or attached to this transmission is strictly prohibited. If you have received this transmission in error, please immediately notify the sender by telephone or return e-mail and delete the original transmission and its attachments without reading or saving them in any manner. Thank you. *
Re: UL 60950, Section 6.1.2.1
Hi Richard: For those who want to read the UL60950 Section 6.1.2.1, I have written the specific parts of the section that I have questions on. Otherwise, here are my questions and comments: 1) If the bridging components are left in place, do I still have to meet the 10 mA requirement? No. The standard is quite clear that the Figure 6A, 10 mA, test is only performed if components are removed for the electric strength test. Note the statement: If this option is chosen, an additional test... is performed with all components in place. 2) If so, at which test voltage, the 1.5kV/1.0kV or EUT's rated voltage/range? The test voltage is the EUT rated voltage, not the electric strength test voltage. The paragraph describing what to do if components are removed, implies that if the components are left in place, the 10 mA test is not performed, only that the components shall not be damaged. But the section describing the passing requiring requirements does not make that distinction. They are part of an 'and' condition. The standard implies that some circuits may have components connecedt between the telecom network and earth. For such circuits -the components could load the electric strength test such that the test would appear to be a failure, or -the test voltage could damage the components. Therefore, the standard allows such components to be removed such that only the insulation is tested (and the components are not damaged). However, the standard requires a degree of isolation between the telecom network and earth such that the impedance is not less than 7 kohms for a 120-V source (120 V/10 mA - 5 kohms). 3) If the 10 mA test is not required, when the bridging components are left in place, then what is the reasoning for having these components be able to exceed the 10 mA, when those components that had to be removed, be subject to the 10 mA max current? The problem is that the impedance will either load the hi-pot tester such that it indicates failure or cannot rise to the specified voltage (1 kV or 1.5 kV), or the component cannot withstand the hi-pot test voltage and is destroyed. For these reasons, the line-to-earth components can be lifted for the hi-pot test (1 kV or 1.5 kV), but must be tested by the rated voltage test (120 V or 230 V, 10 mA max). Imagine a non-linear voltage-limiting device between the network line and earth. At working voltages, the device appears as an open circuit. At higher voltages, the device appears as a relatively low impedance (or even near zero ohms). For the hi-pot test, the circuit would indicate failure because of the operation of the voltage-limiting device. For the rated-voltage/10 mA test, the device will appear as a relatively high impedance. In summary: The requirement is for basic insulation between the network line and earth. This insulation is tested by a hi-pot test. In some constructions, the circuit may have components (i.e., impedances) between line and earth. Depending on the components, the hi-pot test may not be possible, or may damage the line- to-earth components. In such cases, the components may be removed for the hi-pot test. However, the impedance of the components between line and earth cannot be less than that determined by the rated-voltage/10 mA test. If you have further questions, or want further clarification, please ask. Best regards, Rich --- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
UL 60950, Section 6.1.2.1
Greetings All, For those who want to read the UL60950 Section 6.1.2.1, I have written the specific parts of the section that I have questions on. Otherwise, here are my questions and comments: 1) If the bridging components are left in place, do I still have to meet the 10 mA requirement? 2) If so, at which test voltage, the 1.5kV/1.0kV or EUT's rated voltage/range? The paragraph describing what to do if components are removed, implies that if the components are left in place, the 10 mA test is not performed, only that the components shall not be damaged. But the section describing the passing requiring requirements does not make that distinction. They are part of an 'and' condition. 3) If the 10 mA test is not required, when the bridging components are left in place, then what is the reasoning for having these components be able to exceed the 10 mA, when those components that had to be removed, be subject to the 10 mA max current? Thanks. Richard Georgerian Compliance Engineer Carrier Access Corporation 5395 Pearl Parkway Boulder, CO 80301 USA Tele: 303-218-5748 Fax: 303-218-5503 mailto:rgeorger...@carrieraccess.com = UL60950 Section 6.1.2.1 Separation of the telecommunication network from earth, Requirements Insulation is subjected to an electric strength test according to 5.2.2. The a.c test voltage is as follows: - for equipment intended to be installed in an area where the nominal ac mains supply voltage exceeds 130 V: 1.5 kV - for all other equipment: 1.0 kV The test voltages apply whether or not the equipment is powered from the ac mains supply. It is permitted to remove components that bridge the insulation, other than capacitors, during electric strength testing. If this option is chosen, an additional test with a test circuit according to figure 6A is performed with all components in place. The test is performed with a voltage equal to the rated voltage of the equipment or the upper voltage of the rated voltage range. During these tests: - there shall be no breakdown of insulation during electric strength testing; and - components bridging the insulation that are left in place during electric strength testing shall not be damaged; and - the current flowing in the test circuit of figure 6A shall not exceed 10 mA = * This e-mail transmission, and any documents, files, or previous e-mail messages attached to it may contain information that is confidential or legally privileged. If you are not the intended recipient, or a person responsible for delivering it to the intended recipient, you are hereby notified that you must not read this transmission and that any disclosure, copying, printing, distribution, or use of any of the information contained in or attached to this transmission is strictly prohibited. If you have received this transmission in error, please immediately notify the sender by telephone or return e-mail and delete the original transmission and its attachments without reading or saving them in any manner. Thank you. *
