Value chain · CLM-1076
In plain terms
In 1980 the electronics that would condition the satellite's power weighed, at the state of the art, more than the whole satellite was allowed to; the design needed them fifty times lighter, and the arrays to run at fifty times the voltage anyone had flown.
The claim as recorded
The programme's April 1980 statement of the power-distribution problem: "Typical designs require 9 x 10^6 kW as input power to the satellite r-f converters to deliver 5 x 10^6 kW to the ground utility grid. Existing satellite power processors, with specific weights of 10 kg/kW, would add a clearly unacceptable 90 x 10^6 kg to an SPS reference designs having a total weight of 30 to 50 x 10^6 kg. Conceptual studies performed by Westinghouse and GE have projected that specific weights might be reduced to the range of 1 to .2 kg/kW"; the issue-tree goals are "0.4 - 1.0 kg/kW, 90% Efficiency, 30 Year Life", switchgear 99.9 per cent, rotary joint 200 kA, conductors 0.124 W/g; "It is generally believed that present solar array designs will not operate satisfactorily at voltages above 400V"; a solid-state or low-voltage array "incurs a 5 x 10^6 kg mass and 4% loss penalty"; the workshop chair's summary: "present aerospace power processing technology corresponds to a power density of 10-15 kg/KW. Thus the power processing alone, using present technology, weighs more than the total projected system"; JSC's plasma tests found insulation made arcing worse, onset falling "from -3,000V to -250V", so that "a high voltage system could well be less vulnerable to arcing problems"; Westinghouse's 1990 converter goals "0.197 kg/kW and efficiency goal of 96% for klystrons and 0.271 kg/kW and 92% for solid state" "appear to be reasonable".
Evidence behind this: T3, a power-distribution abstract with a rendered issue-tree table, a workshop chair's summary, JSC plasma-test results and Westinghouse goals.
Scope and limits
The 10 kg/kW is "existing satellite power processors" in 1980; Williams's "around 5 or 6 kg/KW" for "35-50 million kg" at 5 GW is the page's own figure (35 to 50 x 10^6 kg over 5 x 10^6 kW is 7 to 10); the goals are goals. The JSC plasma results are 10 m panels in an argon chamber at 10^5/cc.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF p.384 / printed 362, render read: Table 1 as stated; the 9 x 10^6 kW, 10 kg/kW, 90 x 10^6 kg and Westinghouse/GE sentences; the 400V sentence. PDF p.383 / printed 361, normalised: "The magnetron can be operated from a single 20 kV buss and has internal voltage tolerance (5 to 10%) which permits direct connection to a 20 kV solar array"; "Power processing, necessary for 100% of the power, incurs a 5 x 10^6 kg mass and 4% loss penalty"; PDF p.385 / printed 363: "Energy storage is required by the SPS (1 to 15 mWh) and EOTV (0 to 300 kWh)". PDF p.398 / printed 376: "The total weight of the satellite power system is projected to be between 35-50 million kg for a 5 GW system. This corresponds to a specific power density of around 5 or 6 kg/KW"; the 10-15 kg/KW sentence as quoted. PDF p.395 / printed 373: "Not only was the insulation not effective in reducing current leakage at voltages over 100V, but it also caused increased currents and transient arcing"; "adding large areas of insulation was observed to reduce the on-set voltage for arcing from -3,000V to -250V"; "a high voltage system could well be less vulnerable to arcing problems". PDF p.389 / printed 367: the Westinghouse goals as quoted; "Antenna module cable weight is very sensitive to the amplifier voltage up to about 500 Vdc".
Basis: kg/kW of power processing; per cent efficiency; volts; kg mass penalty
Related records
- Answers question
- QST-002 not published in this releaseQST-018 not published in this release
Cite this
energyaperture.com/c/clm-1076
CLM-1076, Energy Aperture, as of 1980-04.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-449
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