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| 18 | Figure 1: Illustrated are the ITU-T standards for Central Office, Access Equipment and Customer Premises equipment. Table 2: List of the most current July 2017 ITU-T K.21 Basic and Enhanced tests. ITU-T standards are well organized as long as you know how to navigate the system. The latest version of the standard can be freely downloaded from https://www.itu. int/rec/T-REC-K/en. Specific test requirements (e.g., voltage and current levels, impedances, test duration, pass/fail criteria) are listed in K.20, K.21, and K.45, depending on the application. Each of these uses the general test setups and test schematics defined in K.44. The illustration below can be used to help you determine which standard is the one you need to be concerned about for your product. Please note that ITU-T does not distinguish between Ethernet Power Sourcing Equipment (PSE) and Powered Devices (PD). They both use the same standards. Residential areas typically do not have good grounding systems in place, making them more prone to environmental surges. Therefore, the K.21 tests are more difficult than the others. Generally, if you can pass K.21 then you can pass K.20 and K.45 as well. ITU-T is fairly simple to follow since it explicitly lists Ethernet and PoE requirements in tests 2.1.7 through 2.1.11 for external ports and tests 7.4 through 7.7 for internal ports. Conveniently, external and internal ports both have the same requirements. All surge waveforms are generated from a standard 8/20 Combination Wave Surge Generator. These tests are summarized in the Table below: ITU-T K.21 Resistibility of Telecommunications Equipment to Overvoltage and Overcurrent K.21 Test Test Description K.44 Test Setup Coupling Basic test levels Enhanced test levels Notes 2.1.10 & 7.6 UTP Impulse Voltage Test Figure A.6.7-3a R=5Ω ±2.5kV, x5 ea ±6kV, x5 ea Must be 1st test 2.1.10 & 7.6 Insulation Resistance Test Figure A.6.7-3 Ammeter 500VDC 500VDC Must be 2nd test. Pass if R>2MΩ. 2.1.7 & 7.7 UTP Transverse Test Figure A.6.7-5 R1 = 10Ω, R2 = 10Ω ±2.5kV, x5 ea ±6kV, x5 ea 2.1.11 & 7.5 PoE Mode A & B Transverse Test Figure A.6.7-2 R = 10Ω, R1 = 10Ω ±2.5kV, x5 ea ±6kV, x5 ea 2.1.8 STP/UTP Simultaneous Port to Earth Figure A.6.7-4 R=10, x8 ±2.5kV, x5 ea ±6kV, x5 ea This test is only for external cables. 2.1.9 & 7.4 STP Simulta- neous Port to Earth Figure A.6.7-6 R=5Ω ±2.5kV, x5 ea ±6kV, x5 ea Same as 1st test but with shield added.