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Part 1 - Dc Power Principles - Introduction to Eltek Power Systems
- 1. Introduction to Eltek PowerSystems DC Power Principles – Part 1 P Massey Security level: Internal use
- 2. Why -48Vdc? 27 July2022 Slide 2 • Safety – Less than 60Vdc is considered as SELV (Safety Extra Low Voltage) • Distance – Telecom equipment is powered by -48Vdc from our power systems in the exchange. Distances between the exchange and consumers can be kilometres. Therefore -48V is considered the best compromise for safety, distance and cable size. • Wire corrosion – It was found in the early days that when telephone wires were run in the ground using negative earth (+48Vdc), if there was a break in the insulation, then the copper wire would corrode due to electrolysis. By moving the earth to the positive (-48Vdc), corrosion by electrolysis was prevented.
- 3. DC Power systemoverview 27 July 2022 Slide 3 BATTERY DC OUTPUT ~ = AC INPUT Under normal conditions the power system provides DC power to the load and charges the batteries.
- 4. 27 July 2022 Slide4 DC Power system overview BATTERY DC OUTPUT ~ = When the AC mains fails, the battery discharges and supplies the load. AC INPUT X
- 5. DC Power systemoverview 27 July 2022 Slide 5 BATTERY DC OUTPUT ~ = AC INPUT Under normal conditions the power system provides DC power to the load and charges the batteries.
- 6. DC Power systemoverview 27 July 2022 Slide 6 BATTERY DC OUTPUT ~ = AC INPUT The system also filters out noise and disturbances from the AC mains. ~ ~ ~
- 7. DC Power systemoverview 27 July 2022 Slide 7 BATTERY DC OUTPUT ~ = AC INPUT The system also monitors and controls the power output and provides alarms to external monitoring systems
- 8. Types of converters 27July 2022 Slide 8 DC OUTPUT AC INPUT RECTIFIER ~ = Converts AC into DC DC/DC CONVERTER DC OUTPUT DC INPUT = = Converts one DC voltage to another DC voltage INVERTER AC OUTPUT DC INPUT = ~ Converts DC into AC
- 9. Components of aUPS 27 July 2022 Slide 9 A DC UPS is made up of :- - A rectifier - A battery For a AC UPS we add an inverter Battery DC UPS AC INPUT ~ = AC OUTPUT = ~
- 10. Types of converters 27July 2022 Slide 10 BATTERY DC OUTPUT AC OUTPUT = ~ ~ AC INPUT Rectiverter – Combines the functions of a rectifier and an inverter in one. Under normal conditions the rectiverter supplies the AC and DC output and also charges the battery.
- 11. Types of converters 27July 2022 Slide 11 BATTERY DC OUTPUT AC OUTPUT = ~ ~ AC INPUT Rectiverter – When the AC mains fails the battery supplies the DC load and the rectiverter which then converts the DC to AC to continually supply the AC load. X
- 12. DC power systemcomponents 27 July 2022 Slide 12 G DIESEL GENERATOR AC Input AC Input: Typically AC Mains between 110-480V, However other sources of supply can include generators ,UPS etc.
- 13. DC power systemcomponents 27 July 2022 Slide 13 OVP MAINS FUSES Input Protection: Can be provided by either fuses, breakers or other such devices. G DIESEL GENERATOR AC Input
- 14. DC power systemcomponents 27 July 2022 Slide 14 OVP MAINS FUSES G DIESEL GENERATOR AC Input Rectifier #1 Rectifier #2 Rectifier #n REDUNDANT RECTIFIER SYSTEM AC/DC Rectifier #n Rectifier: A power supply which converts Alternating Current to Direct Current; typically for Telecoms output below 60V
- 15. DC power systemcomponents 27 July 2022 Slide 15 OVP MAINS FUSES G DIESEL GENERATOR AC Input Rectifier #1 Rectifier #2 Rectifier #n REDUNDANT RECTIFIER SYSTEM AC/DC Rectifier #n CONTROLLER Monitor & Control unit (Controller): Monitors the system and generates alarms if an event occurs and can control the charging of the batteries. outside of normal operation.
- 16. DC power systemcomponents 27 July 2022 Slide 16 OVP MAINS FUSES G DIESEL GENERATOR AC Input Rectifier #1 Rectifier #2 Rectifier #n REDUNDANT RECTIFIER SYSTEM AC/DC Rectifier #n CONTROLLER BATTERY STRING BATTERY STRING Battery Bank/String: A battery bank is 1 or more strings. A battery string is a number of batteries connected in series to provide the required operating voltage.
- 17. DC power systemcomponents 27 July 2022 Slide 17 OVP MAINS FUSES G DIESEL GENERATOR AC Input Rectifier #1 Rectifier #2 Rectifier #n REDUNDANT RECTIFIER SYSTEM AC/DC Rectifier #n CONTROLLER BATTERY STRING BATTERY STRING LVBD Low Voltage Battery Disconnect: To prevent deep discharging of the batteries. Operated by the controller when a user-configured low battery voltage point is reached.
- 18. DC power systemcomponents 27 July 2022 Slide 18 OVP MAINS FUSES G DIESEL GENERATOR AC Input Rectifier #1 Rectifier #2 Rectifier #n REDUNDANT RECTIFIER SYSTEM AC/DC Rectifier #n CONTROLLER BATTERY STRING BATTERY STRING LVBD LVLD Low Voltage Load Disconnect: Reduces the drain on the batteries by non-priority loads. Operated by the controller when a user defined low battery voltage point is reached.
- 19. DC power systemcomponents 27 July 2022 Slide 19 OVP MAINS FUSES G DIESEL GENERATOR AC Input Rectifier #1 Rectifier #2 Rectifier #n REDUNDANT RECTIFIER SYSTEM AC/DC Rectifier #n CONTROLLER BATTERY STRING BATTERY STRING LVBD LVLD BATTERY DISTRIBUTION Distribution: System hardware for distributing the DC power to the load. Hardware can include; battery breakers, MCB’s or blade fuses.
- 20. DC power systemcomponents 27 July 2022 Slide 20 OVP MAINS FUSES G DIESEL GENERATOR AC Input Rectifier #1 Rectifier #2 Rectifier #n REDUNDANT RECTIFIER SYSTEM AC/DC Rectifier #n CONTROLLER BATTERY STRING BATTERY STRING LVBD LVLD BATTERY DISTRIBUTION NON - PRIORITY LOAD PRIORITY LOAD Load - Any equipment connected to the output distribution of the DC system.
- 21. DC power systemcomponents 27 July 2022 Slide 21 OVP MAINS FUSES G AC Input Rectifier #1 Rectifier #2 Rectifier #n REDUNDANT RECTIFIER SYSTEM AC/DC Rectifier #n CONTROLLER DIESEL GENERATOR NON - PRIORITY LOAD LVBD BATTERY DISTRIBUTION BATTERY STRING LVLD PRIORITY LOAD BATTERY STRING Complete system - However some components such as LVLD for example, are optional.
- 22. Experience the power. Experiencethe power. Experience the power.