Sidactor Protection Thyristor Products Page 60 SIDACtor Protection Thyristor Products

SIDACtor Protection Thyristors 2017 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 02/23/17 UL 60950-1 1 st edition replaced UL 60950 effective July 1, 2006. UL 60950-1 2 nd edition will effectively replace UL 60950-1 1 st edition December 1, 2010. This 2 nd Edition version made several changes but the most important ones to consider for telcom related applications are: 1) the reduced minimum clearances and creepage distances 2) pollution degree 2 and 3 clearance dimensions were modified so they now agree with the IEC 60664-1 Table G.2 values and 3) ringing signals test procedure for FCC Part 68 were corrected The UL 60950-1 1 st edition has an effective date of July 1, 2006, meaning that new products submitted after that date will be evaluated using the 1 st edition version. However, products submitted after December 1, 2010 will be evaluated using the 2 nd edition version. Therefore, between July 2006 and December 2010, the equipment may be tested to either 1 st or 2 nd edition. Products certified by UL to requirements prior to these effective dates may continue to be certified without further reinvestigation unless otherwise indicated specifically by UL. The Technical Harmonization Committee (THC) 62368 is considering the development of a new U.S./Canadian bi- national standard based on a new IEC Standard (February 2010 expected completion date). The IEC is developing a new hazard-based standard for Audio/Video, Information Technology and Communication Technology Equipment, which will eventually replace the existing Telcom Standard (IEC 60950-1) and the Audio/Video Standard (IEC 60065). This safety standard is intended to prevent injury or harm due to electrical shock, energy hazards, fire, heat hazards, mechanical hazards, radiation hazards, and chemical hazards. After the divestiture of the AT&T/Bell system, the National Electric Code (NEC) implemented Article 800-4, which mandates that "all equipment intended for connection to the public telephone network be listed for that purpose" in order to ensure electrical safety. A manufacturer can meet this requirement by listing their product with Underwriters Laboratories under UL 60950-1 (based on IEC 60950-1,). The NEC requires all telecommunication wiring that enters a building to pass through a primary protector, which is designed to limit AC transients in excess of 600 V rms. These transients are due to the fact that telephone lines run in close proximity to AC power lines. Most telecommunication equipment uses a secondary overvoltage protector such as the SIDACtor device. The secondary devices typically limit transients in excess of 350 V rms. Therefore, a potentially dangerous condition exists because of the voltage threshold difference of the primary protector and the secondary protector. To minimize this danger, compliance with UL 60950-1 is required. UL 60950- 1 covers equipment with a rated voltage (primary power voltage) not exceeding 600 V and equipment designed to be installed in accordance with the NEC NFPA 70. This standard does not apply to air-conditioning equipment, fire detection equipment, power supply systems, or transformers. It defines three classes of equipment: Class 1 -protection achieved by basic insulation Class 2 -protection achieved by double or reinforced insulation Class 3 -protection relying upon supply from SELV circuits (voltages up to 40 V peak or 60 V dc) UL 60950-1 also defines five categories of insulation: Functional Basic Supplementary Reinforced Double The following definitions assist in understanding UL 60950-1: Creepage distance is the shortest distance between two conductors, measured along the surface of the insulation. DC voltages are included in determining the working voltage for creepage distances. (The peak value of any superimposed ripple or short disturbances, such as cadenced ringing signals, shall be ignored.) Clearance distance is the shortest distance between two conductive parts or between a conductive part and the outer surface of the enclosure measured through air. DC voltages and the peak value of any superimposed ripple are included in determining the working voltage for clearance distances. Creepage and clearance distances are subject to the pollution degree of the equipment: Pollution degree 1-components and assemblies sealed to prevent ingress of dust and moisture Pollution degree 2-generally applicable to equipment covered by UL 60950-1 Pollution degree 3-equipment subject to conductive pollution or to dry non-conductive pollution, which could become conductive due to expected condensation UL 60950-1 defines a secondary circuit as a circuit with no direct connection to a primary circuit and defines a primary circuit as a circuit directly connected to the ac mains supply. SELV (Secondary Electrical Low Voltage) Secondary circuit whose voltage values do not exceed a safe value (voltage less than hazardous levels of 42.4 V peak or 60 V dc); regarded as not hazardous under dry conditions for an area of contact equivalent to the size of a human hand TNV Telecommunication Network Voltage (a secondary circuit) (please refer to Table 3.49 on next page) TNV-1 This is a TNV circuit with normal operating voltages that do not exceed SELV limits and has exposure to overvoltages TNV-2 This is a TNV circuit with normal operating voltages that do not exceed SELV limits and has no exposure to overvoltages TNV-3 This is a TNV circuit with normal operating voltages that exceed SELV limits and has exposure to overvoltages UL 60950-1 Terminology Regulatory Requirements (continued) UL 60950-1 2nd Edition

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