UL SUBJECT 2391-2002 Outline of Investigation for Equipment with Remote Feeding Telecommunication Circuits Intended for Backwards Compatibility in Legacy Telecommunication Equipmen.pdf

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1、September 6, 20021SUBJECT 2391OUTLINE OF INVESTIGATIONFOREQUIPMENT WITH REMOTE FEEDING TELECOMMUNICATION CIRCUITSINTENDED FOR BACKWARDS COMPATIBILITY IN LEGACYTELECOMMUNICATION EQUIPMENTIssue Number: 2September 6, 2002COPYRIGHT 2001, 2002 UNDERWRITERS LABORATORIES INC.SEPTEMBER 6, 2002SUBJECT 23912N

2、o Text on This PageCONTENTSFOREWORD 4INTRODUCTION1 Scope .52 General 63 Definitions 6CONSTRUCTION4 Accessibility 65 Clearances, Creepage Distances and Solid Insulation .7PERFORMANCE6 Electric Shock 77 Electric Strength Test 88 Force Test .9MARKING9 Markings .9SEPTEMBER 6, 2002 SUBJECT 2391 3FOREWORD

3、A. This Outline of Investigation contains basic requirements for products covered by UnderwritersLaboratories Inc. (UL) under its Follow-Up Service for this category within the limitations given below andin the Scope section of this Outline of Investigation. They are subject to revision as further e

4、xperience andinvestigation may show is necessary or desirable.B. The observance of these requirements by a manufacturer is one of the conditions of the continuedcoverage of the manufacturers product.C. A product which complies with the text of this Outline of Investigation will not necessarily be ju

5、dged tocomply with the Outline of Investigation if, when examined and tested, it is found to have other featureswhich impair the level of safety contemplated by these requirements.D. A product that contains features, characteristics, components, materials, or systems new or differentfrom those cover

6、ed by the requirements in this Outline of Investigation, and that involves a risk of fire orof electric shock or injury to persons shall be evaluated using appropriate additional component andend-product requirements to maintain the level of safety as originally anticipated by the intent of thisOutl

7、ine of Investigation. A product whose features, characteristics, components, materials, or systemsconflict with specific requirements or provisions of this Outline of Investigation does not comply with thisOutline of Investigation. Revision of requirements shall be proposed and adopted in conformanc

8、e with themethods employed for development, revision, and implementation of this Outline of Investigation.E. UL, in performing its functions in accordance with its objectives, does not assume or undertake todischarge any responsibility of the manufacturer or any other party. The opinions and finding

9、s of ULrepresent its professional judgement given with due consideration to the necessary limitations of practicaloperation and state of the art at the time the Outline of Investigation is processed. UL shall not beresponsible to anyone for the use of or reliance upon this Outline of Investigation b

10、y anyone. UL shall notincur any obligation or liability for damages, including consequential damages, arising out of or inconnection with the use, interpretation of, or reliance upon this Outline of Investigation.F. Many tests required by the Outline of Investigations of UL are inherently hazardous

11、and adequatesafeguards for personnel and property shall be employed in conducting such tests.SEPTEMBER 6, 2002SUBJECT 23914INTRODUCTION1 Scope1.1 This Outline of Investigation covers supplementary requirements for communication circuit packs andshelves with remote feeding telecommunication circuits

12、intended for backwards compatibility with frames,shelves and backplanes.1.2 The equipment covered is limited to that which forms part of a TELECOMMUNICATION NETWORK up to andincluding the DEMARCATION POINT. The circuitry associated with this type of equipment is intended to beinstalled and located i

13、n SERVICE ACCESS AREAS only, which may or may not be provided by the equipmenthousing. This equipment is generally considered Central Office Equipment, though it may be deployedelsewhere in similarly controlled environments.1.3 This Outline supplements the Standard for Safety of Information Technolo

14、gy Equipment, UL 60950,Third Edition, because of the need for backwards compatibility of new equipment with equipment alreadyinstalled in the existing telecommunications infrastructure. In particular, spacings associated withconnectors and similar interfaces that are part of the installed base are i

15、ncompatible UL 60950, ThirdEdition, based on the existing working voltages. Certain types of equipment have provided voltage-biasedcircuitry for many years which are directed within the TELECOMMUNICATION NETWORK. These high voltages areutilized to power signal repeaters and remote terminal equipment

16、 where AC power cannot be relied uponfor operation due to the tremendous downtime present with AC utility functionality. The circuits are notused in customer accessible areas where accidental contact would present a potential hazard. Networkservice personnel are considered to be aware of the apparen

17、t hazards associated with this type ofcircuitry.1.4 Examples of equipment requiring backwards compatibility are:a) Circuit packs or cards with existing or new technologies designed to be installed into shelfassemblies that form part of a service providers existing infrastructure;b) Shelf assemblies

18、intended as replacements for existing shelf assemblies mounted in frameline-ups that form part of a service providers existing infrastructure; andc) Shelf assemblies or enclosures intended as replacements for existing service providerinfrastructure equipment that are required to be compatible with c

19、ards or circuit packs already inservice.SEPTEMBER 6, 2002 SUBJECT 2391 52 General2.1 This Outline is to be used in conjunction with in the Standard for Safety of Information TechnologyEquipment, UL 60950, Third Edition. With the exception of the requirements stated within this Outline, andas permitt

20、ed in 2.2, equipment with remote feeding telecommunication circuits shall comply with allapplicable requirements in UL 60950, Third Edition.2.2 These requirements may also be used for investigations of equipment with remote feedingtelecommunication circuits to the Standard for Information Technology

21、 Equipment, UL 1950, Third Edition,provided that the appropriate parallel requirements referenced in this Outline are applied.3 Definitions3.1 For the purpose of this Outline of Investigation, the following definitions apply that are not alreadydefined in Standard for Safety of Information Technolog

22、y Equipment, UL 60950, Third Edition. Terms inSMALL CAPS that are not defined in this Outline are defined in the Definitions section of UL 60950, ThirdEdition.3.2 DEMARCATION POINT The point at which a telecommunications carriers equipment, or responsibilityends, and the subscribers equipment or res

23、ponsibility begins. This may be at a junction box on the sideof a building, or a patch panel within a building. Residential lines tend to be demarcated outside, whilemultiline phone systems in businesses tend to be demarcated at a patch panel, or terminal block insidethe premises.3.3 RFT CIRCUIT (Re

24、mote Feeding Telecommunication Circuit) A SECONDARY CIRCUIT within the equipment,intended to supply or receive DC power via a TELECOMMUNICATION NETWORK at voltages exceeding the limitsfor TNV CIRCUITS, and on which overvoltages from TELECOMMUNICATION NETWORKS are possible.3.4 RFT-V CIRCUIT AnRFT CIR

25、CUIT which is designed and protected so that under normal operatingconditions and single fault conditions the voltages are limited and the accessible area of contact islimited (see 4.1).CONSTRUCTION4 Accessibility4.1 In a SERVICE ACCESS AREA, bare parts of RFT CIRCUITS shall be located or guarded so

26、 that accidentalshorting to SELV CIRCUITS or to TNV CIRCUITS, for example by TOOLS or test probes used by SERVICE PERSONNEL,is unlikely. RFT CIRCUITS are not required to be guarded from unintentional contact with bare parts duringservice operations involving other parts of the equipment.4.2 In a RES

27、TRICTED ACCESS LOCATION, the requirements for OPERATOR ACCESS AREAS apply, except contact withbare parts of an RFT CIRCUIT is permitted by the test finger, Figure 2A of the Standard for Safety ofInformation Technology Equipment, UL 60950, Third Edition.SEPTEMBER 6, 2002SUBJECT 239165 Clearances, Cre

28、epage Distances and Solid Insulation5.1 Clearances, creepage distances and solid insulation requirements associated with RFT CIRCUITS aredetermined based on the working voltage of the circuit in accordance with either:a) Sub-clauses 2.10 and 5.2 of Standard for Safety of Information Technology Equip

29、ment, UL60950, Third Edition orb) The Electric Strength Test, Clause 7 of this Outline.PERFORMANCE6 Electric Shock6.1 An RFT CIRCUIT is so designed and protected that under normal operating conditions the voltage,current, power and the accessible area of contact are limited.6.2 The steady state open

30、 circuit voltage from each conductor to earth that is supplied to aTELECOMMUNICATION NETWORK shall not exceed:a) 140VDCorb) 200 V DC, provided that a monitoring device is used that limits the current to the following:1) In the event of a single fault, with and without the RFT-V CIRCUIT conductor bei

31、ngearthed, the output voltage during the first 200 ms for each RFT-V CIRCUIT conductor withrespect to earth, shall not exceed the limits of Figure 2D of Standard for Safety ofInformation Technology Equipment, UL 60950, Third Edition, as measured across a 5k2% resistor with all other loads disconnect

32、ed. After 200 ms, the above limits apply.2) With one conductor of the RFT CIRCUIT earthed, the open circuit voltage of the otherconductor shall not exceed the maximum RFT CIRCUIT supply voltage after 200 ms. For anRFT CIRCUIT whose voltage exceeds 140 V DC under normal operating conditions, thecurre

33、nt between the other conductor and earth measured through 2 k2%, under anyexternal load condition, shall not exceed the relevant line-to-earth limit given in Figure6.1. After 10 seconds, the current shall not exceed 10 mA DCThis is generated text for figtxt.SEPTEMBER 6, 2002 SUBJECT 2391 76.3 The ma

34、ximum power that can be supplied to any load connected to the TELECOMMUNICATION NETWORKshall be limited to 100 W after 1 second.7 Electric Strength Test7.1 Clearance, creepage distances and distance through insulation between the RFT CIRCUIT and TNV, SELVor accessible parts shall withstand the appli

35、cation of an electric strength test in accordance withsub-clause 5.2 of Standard for Safety of Information Technology Equipment, UL 60950, Third Edition, ata test potential of 1000 V AC rms (1414 V DC/peak) for a period of 1 minute without insulation breakdown.7.2 Power-dissipating component parts,

36、electronic devices, and electrolytic capacitors bridging theinsulation between the circuits under test within 7.1 are to be removed or disconnected in such a mannerthat the insulation, rather than these components, is subjected to the full electric strength test potential.Figure 6.1 Maximum current

37、after a single faultSEPTEMBER 6, 2002SUBJECT 239188 Force Test8.1 When provided with a guard or cover that prevents unintentional contact during normal operation, the10 N steady force test is not applied to wire-wrap pins utilized on telecommunication equipment coveredby this Outline of Investigatio

38、n.MARKING9 Markings9.1 NETWORK TELECOMMUNICATION equipment utilizing voltages higher than those covered by TNV-1 or TNV-3limits shall be provided with a marking, readily visible to service personnel, which includes the followingor equivalent text:CAUTIONRisk of Electric ShockVoltages up to _ V may be present on telecommunication circuits.SEPTEMBER 6, 2002 SUBJECT 2391 9SEPTEMBER 6, 2002SUBJECT 239110No Text on This Page