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REMOTE POWER SYSTEM ”Turning your copper into gold” Exit Eltek What? Powering remote electronics utilizing the existing copper network Also known as ‘span power’ or ‘line power’ Powering a broadband/xDSL network Increased bandwidth requires active components (DSLAM) closer to the end user Solutions for power distributions required 2 Eltek What? CO site with existing 48Vdc system and battery backup Typical distance to remote DSLAM site is 5 to 10km 3 Eltek Remote Powering concept Existing twisted pairs now made available for power distribution. ±190Vdc, 250mA Fed by existing 48Vdc or integrated Rectifier solution AC or DC Remote DSLAM NODE Central Office n numbers of Remote Nodes Remote DSLAM NODE Dc/dc converter in the Remote End supplying -48V Remote DSLAM NODE 4 Eltek Why? CAPEX & OPEX reductions Utilize the existing infrastructure Copper network, X-connects, etc. Eliminate the requirement for batteries and local power utilities Reduces the size of the DSLAM significantly Battery maintenance eliminated Increased speed of xDSL roll-out 5 Eltek How? RFT: Remote feeding telecommunication circuit Remote Power feeding standard: IEC60950-21/GR-1089 Power limitation: 100W per channel (circuit) RFT-C circuits: Max. 60 mA, maximum 1667V (100VA) normally limited to 800V OR RFT-V circuits: 200Vdc referred ground (400Vdc potential) OVS and ground leakage current detection Eltek only have this type of equipment, why? 6 Eltek How? Block schematics based on Eltek products 7 Modules System Solutions Flatpack DC/DC Converter 48/190 Flatpack VA Limiter Remote End Converter Flatpack RPS Integrated Exit Eltek Central Office modules Flatpack DC/DC Converter Flatpack VA Limiter Input: 48Vdc (40-60Vdc) Input: ±190Vdc Output: 190Vdc of 1250W Output: ±190Vdc 12 Channels Reliable ”Flatpack” technology (RFT-V Circuits) of 100W Digital current sharing Short circuit proof High temp protection Over voltage shutdown Part no.: 241114.501 CE, UL and NEBS approvals (250mA) Current limiters Over voltage protection Ground leakage current protection (trip current 60mA) 1.000.000h MTBF per channel Part no.: 241258.724 IEC/UL60950-21 (”remote powering safety standard”) 9 Eltek VA Limiter On/Off switch I+ CURRENT SENSE +190V input from dc/dc converters Over load detection Over voltage protection Ground leakage current detect Secondary protection; gas discharge tube Current limiters for lightning and AC power fault protection Over load detection -190V input from dc/dc converters On/Off switch I- CURRENT SENSE 10 Eltek Remote End Converter 5 separate DC/DC converters Primary surge protection integrated Input voltage: 190V-380V Output voltage: 48V Output power: up to 380W depending on site layout (typically 250W) Flexible mounting, eats no space in DSLAM rack Part no: 241258.722 11 Eltek Flatpack RPS 2U Integrated 2U Integrated 2 DC/DC Converters 2 VA Limiters 24 output channels (RFT-V Circuits) Single or dual feed 19”/23” mounting 3U solution with Redundant DC/DC converters is also available 12 Eltek Flatpack RPS 6U Integrated Flatpack 6U Integrated Building block for larger cabinet solutions and expandable systems Up to 6 DC/DC Converters Up to 6 VA limiters Up to 72 output channels 48Vdc feed configurable on site 1 x 250A 3 x 100A 6 x 50A 13 Eltek Real CO site with RPS 14 Site installation System dimensioning Exit Eltek Safety Crossover between telecom and power Above 60V SELV level Important Qualification & identification of twisted pairs Training of installation and maintenance people Follow Eltek installation manuals (including the configuration tool) Grounding of people working on cables is important! 16 Eltek Safety – Voltage levels Classification of voltage levels (GR-1089) A1: 200Vdc / 0.15mA maximum leakage current to ground A2: 200Vdc / 5mA maximum leakage current to ground A3: 200Vdc / 10mA maximum leakage current to ground 17 Eltek Safety – DC IEC 60947-1 – Effects of current on humans beings and livestock (DC) 18 Eltek Safety – DC Dangerous area Our area 19 Eltek Safety – AC Remember difference between DC and AC 30mA AC is accepted as trip current 20 Eltek Safety – Body resistance 2kΩ 1,275kΩ 21 Eltek Safety - Earth leakage detection VA Limiter takes care of the safety in the system, on earth fault it trips on 60mA 190V/2,5kohm ≈ 72mA -> earth fault 2kohm (typical person) + 0,5kohm (typ. cables) If the earth leakage current exceeds 60mA, the VA Limiter shuts off within 5ms and runs in a hick-up mode limiting the average current to ground to less than 5mA. 22 Eltek Safety – Overload Isolated (non grounded) person/user (should not happen..) 380V/1,275kohm ≈ 300mA VA limiter channel will go into overload and shut down, but... 23 Eltek Safety – Marking X-connect example Proper marking DSLAM cabinet 24 Eltek Safety – cable qualification From Eltek User Guide 25 Basic electrical considerations Block diagram Fixed Parameters Remote End Converter Line Impedance Stability criteria's Exit Eltek Block diagram Central Office Remote site VA Limiter Remote Unit Line impedance [Ohm] 190V-380V/48V DC/DC Converters I [mA] VA limit VA limit Vco [V] Vremote [V] 48V to DSLAM +190 GND -190 Cable length [m, km, kft] VA limit 27 Eltek Fixed Parameters Central office voltage ±190Vdc = 380V Max current Derived from max output power, safety requirements (GR1089-CORE, IEC/UL60950-21): 100VA (W) per channel 380V Imax = Pmax/Vco = 100W/380V = 263 mA Safety margin and tolerances must be taken into account The maximum input current of the Remote End Converter must be limited to less than the maximum output current of the VA Limiter (next slide) 28 Eltek Fixed Parameters cont’ current Maximum 263 mA 238 mA 235 mA Tolerance VA Limiter (5%) Worst case maximum output current VA Limter Tolerance Remote End Converter (1%) Worst case maximum input current Remote End 29 Eltek Remote End Converter Max input current: 235 mA Efficiency: ~86% This steals power from the CO Power out = 86% of Power in Pin = Vin * Iin input Output losses 30 Eltek Line Impedance Specific resistance for copper: 0.018 Ohm/mm2/m (at 30°C) Resistance per km/kft for Cable size: 0.9 mm (AWG 19): r=27.6 Ohm/km, 8.4 Ohm/kft 0.6 mm (AWG 22): r=55.3 Ohm/km, 16.8 Ohm/kft 0.5 mm (AWG 24): r=87.8 Ohm/km, 26.8 Ohm/kft 0.4 mm (AWG 26): r=139.7 Ohm/km, 42.6 Ohm/kft Max impedance: The maximum line impedance is calculated from the stability criteria Next slides 31 Eltek Stability 1 The obvious The power consumption has to be less than the power available If the power consumption exceeds the power supplied, the power train will collapse 32 Eltek Stability 2 Dc/dc converters has inverse impedance characteristics (1/R) The load is constant If the input voltage drops, the converter will draw higher current to maintain the output voltage (with a constant power load) When the converter draws more current, the input voltage will drop further... Constant power: Pin Vin I in Constant power load 33 Eltek Stability 3 Too high line impedance will result in decreasing output power for increasing current REC input power vs input current Z line Rloop = 1200 80 Vco Z line 2 I max Rloop = 1000 70 380 V 2 235 mA Rloop = 800 Rloop = 600 Input power [W] 60 ~ 800 Rloop = 400 50 40 30 Unstable! 20 10 0 0 50 100 150 200 250 Input current [mA] 34 Eltek Line Impedance cont’ Now we can find maximum cable length: AWG 19: 13.6 km / 44.7 kft Z max lmax AWG 22: 6.8 km / 22.3 kft 2r AWG 24: 4.3 km / 14.0 kft AWG 26: 2.7 km / 8.8 kft To increase length pairs can be paralleled 2 pairs – double length 3 pairs – triple length 35 Eltek Paralleling of pairs Cable resistance is increased 1 1 1 1 ... Rtotal R1 R2 R3 The current is shared between the pairs If the cable resistance is equal, the current is shared equally The touch current remains the same Only single wire out of and into the modules connectors 36 Eltek Line Impedance cont’ How does the line impedance affect the output power? Linearly decreasing with increasing line impedance Max Output Power per channel vs line impedance 90 Output Power [W] 80 70 60 50 40 30 20 10 0 0 200 400 600 800 1000 Line Impedance [Ohm] 37 Eltek Line Impedance cont’ Knowing the max line impedance, the minimum power per channel can be calculated Pout Pin Pin Vin I in Vin Vco Z line I in Pout Vco Z line I in I in Pout (380 800 0.235) 0.235 0.86 38.8 W 38 Eltek Configuration Site dependent parameters Power consumption How many channels? How many pairs? Wire gauge Calculated parameters Max line impedance Max Cable length 39 Eltek Site Dependent parameters Power Consumption This is what the power system do; deliver a certain amount of power to the Remote End How many channels? Adding channels means adding power How many pairs? Adding (parallel) pairs means increasing cable length Wire gauge As seen, the wire gauge affects the line impedance. Use as low AWG as possible... 40 Eltek Calculated Parameters Max line impedance The maximum line impedance is calculated from the maximum power drop of the lines Max Cable length The cable length can easily be calculated from the maximum impedance as long as you know the gauge Vco Pmin Z 2 I max n I max Z l r r 139.7 Ω/km for 26 AWG 41 Excamples – Cable Calculator tool Exit