6, July 2015

ESA Open Invitation To Tender AO8329
Open Date: 02/07/2015
Closing Date: 10/09/2015

Status: ISSUED
Reference Nr.: 15.1QM.07
Prog. Ref.: TRP
Budget Ref.: E/0901-01 – TRP
Tender Type: C
Price Range: 200-500 KEURO
Establishment: ESTEC
Directorate: Directorate of Technical & Quality Manag
Department: Product Assurance and Safety Department
Division: Materials & Components Technology Divisi
Contract Officer: Wesolowski, Szymon
Last Update Date: 02/07/2015
Update Reason: Tender issue

Electrical Harness is an important contributor in the overall mass of satellites. One way, already investigated in different ESA activities, to decrease the mass of electrical harness is to decrease of the mass of electrical wires by considering different materials or design. A second approach consists to extend the electrical current capabilities toward higher operating temperature, in orderto meet the derating rules defined in ECSS Q-ST-30-11C-rev1, which have been defined beginning of years 2000’s. An analysis of ECSSQ-ST-30-11C-rev1 shows that derating rules for cables and connectors are quite conservative compared to NASA and JAXA requirements,in particular for bundles. These requirements lead to the use of larger bundles in terms of number of wires and wires diameters. Inaddition, the current rules are valid for an ambient temperature of 40C considering a working load of 100%. Due to the increase of spacecraft complexity (number of wires/bundles) and power, thermal modelling is most of the time required to design the harness and to justify any deviation to ECSS derating rules. Validity of the thermal modelling should be validated by test that is time consuming and expensive. A review of ECSS rules could lead, while guaranteeing safe design, to reduce the diameter of the wire or the numberof wires (and associated connectors), that would decrease the mass of the harness and facilitate the integration activities (less wires, less connectors, more flexibility, etc.). A modelling tools based on relevant experiment would be beneficial for the conception and the acceptance of an harness. During this activity the connector and wire applicable derating rules will be analysed and compared to rules applied in similar applications (NASA, MIL, automotive, etc). A Design of Experiment will be defined to provide the necessary data to revisit the derating rules. Modelling or analytical tools shall be delivered. The validation test shall be performed and results shall be compared to modelling predictions. A deep analysis shall be done to define the new derating rules and assess the improvement on harness design, mass and integration. These tasks shall address in priority wires composed of Copper and Copper alloys conductors used in round bundles. Experiment and modelling activities might first be limited to most bundle sizes at common ambient temperature. At that step, consistency with derating rules applicable to connectors shall be checked. Any additional configuration will be considered as an asset. Any limitations concerning the testing and the modelling boundary will be clearly identified in order to prepare any necessary future work. The first objective of this activity is to define accurately the derating rules to be applied for connectors and cables in order toavoid over margin that induce mass and performances penalties. The second objective is toprovide to space community analytical andmodeling tools to avoid heavy testing for harness validation.

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