External Active Thermal Control System

External Active Thermal Control System (EATCS)

Heat Rejection System Radiator (HRSR) weight 2,475 lbs. at ELC-4 (top side)^[1] x 3 units each on S1 & P1 Truss

The heat rejection subsystem (HRS) consists of a base, eight panels, torque panel, torque arm, an interconnected fluid system, a scissors-type deployment mechanism and a computer controlled motor/cable deployment system. Part of the station’s external active thermal control system (EATCS), the HRS radiator rejects thermal energy via radiation.

Plasma Contactor Unit (PCU) weight 350 lbs. at ELC-1 FRAM-2 (top side)^[2] x 2 units on the Truss

The Plasma Contactor Unit (PCU) is used to disperse the electrical charge that builds up by providing an electrically conductive “ground path” to the plasma environment surrounding the ISS. This prevents the electrical discharges and provides a means of controlling crew shock hazard during EVA. There are two PCUs located on the ISS Zenith 1 Truss, both of which are operated during EVA.

Pump Flow Control Subassembly (PFCS) weight 235 lbs. at ESP-1 FRAM-1^[3] x 12 units in total, 2 on each IEA x4 & 2 each on P6/S6 Spacers

Each external loop contains a Pump & Flow Control System (PFCS) which contains most of the controls and mechanical systems that drive the EEATCS. There are 2 pumps per PFCS which circulate ammonia throughout the external coolant loops

Utility Transfer Assembly (UTA) at ESP-2 FRAM-8 (keel side)^[4] x 2 units on the Truss

The UTA is a processor that allows power, signals and data to flow across the SARJ by roll rings incorporated within.

Flex Hose Rotary Coupler (FHRC) weight approx. 900 lbs. x 1 unit each on S1 & P1 Truss. The FHRC provides the transfer of liquid ammonia across the Thermal Radiator Rotary Joint (TRRJ) between the P1 & S1 truss segments and the Heat Rejection System Radiators (HRSRs)^[5], ELC-4 FRAM-5 (keel side)^[6]
Pump Module (PM) weight 780 lbs. x 1 unit each on S1 & P1 Truss. The PM is part of the station’s complex External Active Thermal Control System (ETCS), which provides vital cooling to internal and external avionics, crew members, and payloads. The station has two independent cooling loops. The external loops use an ammonia-based coolant and the internal loops use water cooling.
Ammonia Tank Assembly (ATA) weight 1,702 lbs. x 1 unit each on S1 & P1 Truss. The primary function of the ATA is to store the ammonia used by the External Thermal Control System (ETCS). The major components in the ATA include two ammonia storage tanks, isolation valves, heaters, and various temperature, pressure, and quantity sensors. There is one ATA per loop located on the zenith side of the Starboard 1 (Loop A) and Port 1 (Loop B) truss segments.
Nitrogen Tank Assembly (NTA) weight 550 lbs. each x 1 unit each on S1 & P1 Truss. The NTA provides a high-pressure gaseous nitrogen supply to control the flow of ammonia out of the ATA. The ATA contains two flexible, chambers incorporated into its ammonia tanks that expand as pressurized nitrogen expels liquid ammonia out of them.
Direct Current Switching Unit (DCSU) weight 218 lbs. x 2 units each on the 4 IEAs. The DCSU routes battery power to the MBSU distribution bus to satisfy power demands. In addition to primary power distribution, the DCSU has the additional responsibilities of routing secondary power to components on the PV modules.
Battery Charge/Discharge Unit (BCDU) weight 235 lbs. x 6 each on each of the 4 IEAs. The Battery Charge Discharge Unit (BCDU) is a bidirectional power converter that serves a dual function of charging the batteries during solar collection periods (isolation) and providing conditioned battery power to the primary power buses during eclipse periods.
Main Bus Switching Unit (MBSU) weight 220 lbs. x 4 units on S0 Truss. The MBSUs act as the distribution hub for the EPS system. The four MBSUs onboard the ISS are all located on the Starboard Zero (S0) truss. Each of MBSU receives primary power from two power channels and distributes it downstream to the DDCUs.

Flex Hose Rotary Coupler (FHRC)
FHRC without MLI cover and in situ on the TRRJ
Pump Module (PM)
PM drawing
Ammonia Tank Assembly (ATA)
ATA drawing (cover removed)

Nitrogen Tank Assembly (NTA)
NTA drawing (cover removed)
HPGT being installed onto the ISS
HPGTs on the SL pallet drawing
Cargo Transportation Container (CTC-2)
Inside a CTC Box

Direct Current Switching Unit (DCSU)
DCSU drawing
Battery Charge/Discharge Unit (BCDU)
BCDU drawing
Main Bus Switching Unit (MBSU)
MBSU drawing

Heat Rejection System Radiator (HRSR)
HRSR drawing
Plasma Contactor Unit (PCU)
PCU drawing
Pump Flow Control Subassembly (PFCS)
PFCS MLI removed

References

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External links

example.com

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References

See Also

External links