Energy Power System

1
Energy Power System
2
Electricity

• Electricity is the flow of electrons through a
  conductor
• Electricity will only move through a closed
  circuit, if the circuit is broken the flow of
  electrons stops

3
Electricity (cont.)

• Voltage - Electric potential or potential
  difference, provided by the battery, expressed in
  volts
• Amperage - The strength of an electric current,
  flows through the conductors to the load,
  expressed in amperes
• Resistance - Is present in any load, expressed in
  ohms

4
Light to Power

• Solar Panels collect sunlight and convert them
  into electrical power
• For maximum power solar arrays need to be
  perpendicular to the light rays hitting them.

5
Orbit Cycle

• During the 30 minute eclipse period the batteries
  supply power
• While in insolation period the solar arrays
  provide power while the batteries charge for the
  next eclipse period

6
Primary and Secondary power

• Primary power is high voltage power generated at
  a centralized source
• Before power is delivered to users it is stepped
  down by a transformer to a set voltage (secondary
  power)
• Secondary power is then delivered to the user

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System Overview

• Internal and external systems
• Internal system distributes secondary power
• External distributes primary power
• 8 identical channels of power (0-7)
• Each channel supplies 100 amps of current

8
Internal EPS

• Loads, RPDA, SPDA, DDCU, MBSU, ICC
• Converts primary power to secondary power
• Routes secondary power to any internal systems

9
Loads

• A load is anything that needs electricity to
  function.
• Computers, Lights, Pumps, etc.
• Each load requires a certain current (amps) which
  is specific to that device
• Not all loads are physically inside the station,
  but all are supplied by the same internal
  distribution network

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SPDA/RPDA/DDCU

• Secondary Power Distribution Assembly
• Supports a single channel of power
• A is even channel B is odd channel
• Routes power to one RPDA and six loads
• Reserve Power Distribution Assembly
• Routes power to six loads
• Direct current to Direct current Converter Unit
• This is the unit that converts primary power
  (160 V dc) to secondary power (124 V dc)

11
MBSU/ICC

• Main Buss Switching Unit
• Each support 2 channels of power with a total of
  200 amps
• Routes power to two SPDAs
• Interconnecting Cables
• Create a bridge for two or more MBSUs to share
  power across them

12
External EPS

• SARJ, IEA, ECU, SSU, PCU, BGA, PVA
• Produces primary power from the solar arrays, and
  stores power in batteries for eclipse phase

13
SARJ

• Solar Alpha Rotary Joint
• Rotates 4 channels of power at one time
• Controls rotation parallel to the main station
  truss

14
IEA

• Integrated Equipment Assembly
• Battery Charge Discharge Unit (BCDU)
• When signaled by the ECU the BCDU begins charging
  or discharging the batteries
• Batteries (BAT)
• Batteries store power for use during the eclipse
  phase of the stations orbit

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IEA (continued)

• Direct Current Switching Unit (DCSU)
• Routes power from BGA to batteries, IEA, and
  Internal system
• Direct current to Direct current Converter Unit
  (DDCU)
• Provides Secondary power for IEA components only.

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IEA Thermal control system

• IEA has a self contained thermal control system
  for each channel
• Small radiators under each IEA dissipate heat
  from the SSU as well as batteries and other IEA
  components
• This system functions in the same manner as the
  main TCS for the station
• Pump and Flow Control Subassembly (PFCS) and
  Photovoltaic Radiator (PVR)

17
ECU/SSU

• Electronic Control Unit
• Manages when to charge and discharge the
  batteries
• Sequential Shunt Unit
• Shunts any excess power generated as heat
• Small radiator beneath each PVA radiates heat

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Grounding

• To prevent electricity from arcing across the
  station all electrical devices are grounded to
  the main truss.
• Plasma Contractor Unit (PCU)
• Emits a stream of plasma to ground the space
  stations main truss to space
• Prevents arcing to any external spacecraft during
  docking or EVA

19
BGA/PVA

• Beta Gimbal Assembly
• Rotates one channel of power per BGA
• Controls rotation perpendicular to the main
  station truss
• Photovoltaic Array
• Collects sunlight and converts it into electrical
  power

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Warning Signs of a SOBE

• Red indicator light on the system wall
• Loss of Power (I.e. lights or computer
  unexpectedly shut down)
• Warning through HAL or other system
• Contingency of another SOBE

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Things to check during a SOBE

• For maximum power the panels must be
  perpendicular to the sunlight, if misaligned they
  may not produce enough power
• There are many points were power can be stopped,
  be sure to check them all