SIDACtor ® Protection Thyristors UL 497A UL 497A UL 497A addresses secondary protectors for use in single or multiple pair-type communication circuits intended to be installed in accordance with Article 800 of the National Electric Code (NEC) and to have an operating voltage of less than 150 V rms with respect to Ground. The purpose of UL 497A is to help reduce the risk of fire, electric shock, or injury resulting from the deployment and use of these protectors. UL 497A requirements do not cover telephone equipment or key systems. UL 497A Construction, Risk of Injury, and Performance Requirements Performance Tests The following key performance tests relate to overvoltage protection of the secondary protectors: 5IFi$POTUSVDUJPOwTFDUJPODPWFSTUIFGPMMPXJOH requirements: t t t t t t t t t t t t t 1. Impulse Voltage Measurement Test—Secondary protectors must break down within ±25% of the manufacturer’s breakdown rating when tested in each polarity with a rate of voltage rise of 100 V/μs, ±10%. Note that the manufacturer may assign separate breakdown voltage ratings for the Breakdown Voltage Measurement Test. This requirement only applies to secondary protectors that connect between Tip and Ring of the telephone loop. 2. Breakdown Voltage Measurement Test—Secondary protectors must break down within ±25% of the manufacturer’s breakdown rating when tested in each polarity with a rate of voltage rise no greater than 2000 V/s. The secondary protector is to be mounted in accordance with the manufacturer’s installation instructions and then subjected to the test circuit shown in Figure 3.15. This requirement applies only to secondary protectors connected between Tip and Ring or Tip/Ring and Ground of the telephone loop. 3. Overvoltage Test—Secondary protectors must limit current and extinguish or open the telephone loop without loss of its overvoltage protector, indication of fire risk, or electric shock. Upon completion of this test, samples must comply with the Dielectric Voltagewithstand Test. (FOFSBM 1SPEVDU"TTFNCMZ &ODMPTVSFT *OUFSOBM.BUFSJBM "DDFTTJCJMJUZBOE&MFDUSJD4IPDL 1SPUFDUJPO"HBJOTU$PSSPTJPO $PSET $VSSFOUDBSSZJOH1BSUT *OUFSOBM8JSJOH *OUFSDPOOFDUJOH$PSETBOE$BCMFT *OTVMBUJOH.BUFSJBM 1SJOUFE8JSJOH 4QBDJOH 5IFi3JTLPG*OKVSZwTFDUJPODPWFSTUIFGPMMPXJOH requirements: t .PEVMBS+BDLT t 4IBSQ&EHFT t 4UBCJMJUZ t 1SPUFDUJPOPG4FSWJDF1FSTPOOFM 5IFi1FSGPSNBODFwTFDUJPODPWFSTUIFGPMMPXJOH requirements: t t t t t t t t t t t t t t t t The overvoltage test is used to determine the effects on secondary protectors and is shown in Table 3.48. Test connections are shown in Figure 3.16. (FOFSBM *NQVMTF7PMUBHF.FBTVSFNFOU 0WFSWPMUBHF5FTU &OEVSBODF$POEJUJPOJOH $PNQPOFOU5FNQFSBUVSF5FTU %SPQ5FTU $SVTI5FTU -FBLBHF$VSSFOU5FTU %JFMFDUSJD7PMUBHFXJUITUBOE5FTU 3BJO5FTU .BYJNVN.PNFOU.FBTVSFNFOU5FTU 8FBUIFSPNFUFSBOE.JDSP5FOTJMF4USFOHUI5FTU 5IFSNBM"HJOHBOE'MBNF5FTU &MFDUSJD4IPDL$VSSFOU5FTU .BOVGBDUVSJOHBOE1SPEVDUJPO-JOF5FTU .BSLJOH*OTUBMMBUJPOBOE*OTUSVDUJPOT © 2011 Littelfuse, Inc. Specifications are subject to change without notice. Please refer to www.littelfuse.com for current information. 231 Revised: April 15, 2011 SIDACtor ® Protection Thyristors UL 497A Test Compliance Compliance with the overvoltage test is determined by meeting the following criteria: t $IFFTFDMPUIJOEJDBUPSNBZOPUCFFJUIFSDIBSSFEPSJHOJUFE t 8JSJOHTJNVMBUPS"5ZQF.%2GVTFPS"8(MJOF cord) may not be interrupted t 1SPUFDUPSNFFUTUIFBQQMJDBCMFEJFMFDUSJDWPMUBHF withstand requirements after the completion of the overvoltage tests Table 3.48 UL 497A Overvoltage Test Test L1 Voltage (VRMS) 600 Current (A) 40 Time Comments 1.5 s (Note 1, Figure 4.11) L2 600 7 5s (Note 1, Figure 4.11) L3 600 2.2, 1, 0.5, 0.25 30 min at each current level (Note 2, Figure 4.11) L4 200 V rms or just below the breakdown voltage of the overvoltage protection device 2.2 A or just below the interrupt value of the current interrupting device 30 min (Note 2, Figure 4.11) L5 240 24 30 min (Note 1, Figure 4.11) Notes: 1. Apply Tests L1, L2, and L5 between Tip and Ground or Ring and Ground. 2. Apply Tests L3 and L4 simultaneously from both Tip and Ring to Ground. Figure 3.15 UL 497A Breakdown Voltage Measurement Test R1 50,000 Ω 25 W Figure 3.16 UL 497A Overvoltage Test Circuit for Common Mode (Longitudinal) Overvoltage Tests R2 10 Ω 5 W C1 Variable DC Supply 0-1000 V Current Limiting Resistors Secondary Protector Simulator or Wiring Station V Equipment Under Test Test Specimen Timed Switch Variable AC Voltage Source Equipment Ground Circuit for Differential Mode (Metallic) Overvoltage Tests Current Limiting Resistor Timed Switch Variable Voltage Source Equipment Ground © 2011 Littelfuse, Inc. Specifications are subject to change without notice. Please refer to www.littelfuse.com for current information. 232 Revised: April 15, 2011 Secondary Protector Simulator or Wiring Station Telecommunication Equipment Network Connection Under Test Points Equipment Ground