F4E_D_3CEWVY
F4E-OPE-083 – Information Note on 1MV post-insulator issue
The purpose of this Note is to summarize the current situation regarding the design of the interface box by SIEMENS, explain the rationale behind the request to use the 1MV post-insulators developed by HITACHI, and analyze the impact in case an alternative procurement route must be envisaged.
Background
SIEMENS introduced the possibility to use the 1 MV post-insulators developed by HITACHI inside the Interface Box forming part of their Scope of Supply in the Final Tender submitted in October 2014. Following the signature of the F4E-OPE-083 Contract in December 2014, the topic was discussed during the technical kick-off meeting with SIEMENS, in January 2015. SIEMENS requested then a contact point within HITACHI for direct exchanges on such possibility.
This possibility was then brought forward during the NBPS Interface Management Meeting between IO, F4E and JADA, held in Naka in February 2015, during which JADA provided a first contact point within HITACHI (Kawakami-san, Project Manager of the NBPS for JADA). The efficiency of the discussion was limited by the fact that HITACHI did not attend the Interface Meeting in-person, due to Factory Acceptance Tests taking place in parallel at HITACHI premises.
As the discussion developed it became clear that the context of an exchange between SIEMENS and HITACHI should be well established, due to the particularity of the request: the post-insulators are custom components developed by HITACHI Gas-Insulated Switchgear Division (GIS), for the specific purpose of their integration within the Transmission Line. They do not belong to a product line of HITACHI; they are not intended to be sold outside HITACHI. No certificates of conformity are available, they are considered as “parts” of the Transmission Line, not as individual components.
In April 2015, upon IO and F4E request, JADA continued to discuss with HITACHI GIS, but the feedback received so far has not been positive: consideringSIEMENS existing references on HV DC projects in Asia,HITACHI was of the opinion that SIEMENS should already possess the know-how required. SIEMENS being a competitor of HITACHI in the field, HITACHI GIS Division questioned the motivations of SIEMENS to put forward such request, anticipating concerns in relation to I and, know-how, and asked for additional information and justification of the rationale behind this proposal.
Addressing the request from HITACHI, F4E prepared the following Note, compiling information received from SIEMENS on existing capability in-house on such technology, and alternative ways forward in case the 1 MV post-insulators from HITACHI would not be made available to the Project.
Now that this information is available, a direct exchange between SIEMENS and HITACHI is recommended in order to progress the matter and look for a possible agreement on the request from SIEMENS.
However, it is also important that JADA and F4E follow-up this matter closely with the support of IO and do their best to facilitate an agreement between the two Industrial Companies, since the impact on schedule could be substantial and could affect the ITER HNB development programme.
Introduction and SIEMENS scope of supply
The contribution from Europe to the Neutral Beam Power Supplies system includes the supply of a High Voltage Bushing Assembly transporting the conductors of the Ion Source and Extraction Power Supplies (ISEPS) located on the 1 MV insulated High Voltage Deck to the Transmission Line, which then carries the conductors all the way to the Source.
Figure 1- Side view of the sub-assembly showing the HVD1 Bushing, the Interface Box, the Connecting Piece and the Transmission Line
SIEMENS is in charge of procuring both the High Voltage Deck (HVD1) hosting the Ion Source Power Supplies (ISEPS) and theHigh Voltage (HV) Bushing Assemblyhosting the conductors of ISEPS and bringing them to the Transmission Line TL2.
The High Voltage Bushing Assembly(Figure 3) consists of 2 main sub-components:
-TheHVD1 Bushing, SF6-insulated;
-TheInterface Box, SF6-insulated, connected to the Transmission Line TL2 (procured by JADA) via theConnecting Piece (procured by JADA).
The High Voltage Bushing Assembly, complete of HVD1 Bushing and Interface Box, is supplied by HSP GmbH, a subcontractor of SIEMENS AG for this procurement. HSP is a subsidiary of SIEMENS AG.
Technical design requirements - support of the internal conductors
Connecting Piece (JADA)
The design developed by JADA does not foresee post-insulators inside theConnecting Piece (JADA). This can be explained in part by its limited length (c.a 700mm) and its function of seismic decoupling between the HV Bushing Assembly and the Transmission Line: the Connecting Piece will effectively act as a bellow.
The weight of the conductors hosted inside the Connecting Piece will therefore have to be supported indirectly via the post-insulator(s) located inside the TL2, next to the flange between the Connecting Piece and the TL2.
JADA is also expecting the design of the interface box to foresee post-insulators in order to ensure support of the conductors at both ends of the connecting piece.
Figure 2 – design elements of the Connecting Piece (shown in pink), interface with the Interface Box, supporting means
HVD1 Bushing
The weight of the conductors inside the HVD1 Bushing will be supported by the top flange of the bushing. The design of SIEMENS does not anticipate the need to support their weight from underneath.
Interface Box
TheInterface Box, SF6-insulated, located underneath the Bushing, hoststhe transition of the conductors design inside a spherical shield.
Figure 3 – High Voltage Bushing Assembly and HVD1 Bushing – side view
It should be noted that the mechanical design of the Interface Box is constrained, in particular by the fact that the location of the Bushing is fixed, with no flexibility in the design of the interfacing components (civil work, transmission line already manufactured/constructed), which does not leave much freedom on the design of the insulating support itself.
The design of SIEMENS foresees the use of post-insulators identical to those developed by HITACHI for the NB Transmission Line TL2 in order to support the spherical shield inside the Interface Box (see Figure 4).
Figure 4 - Cross-sections of interface box showing the spherical shield and the insulators (in red). Two design solutions are envisaged: one requiring 3 post-insulators (shown in the figure), one requiring 6 (located higher up inside the interface box, at the top of the spherical shield).
Which 1 MV post-insulator to use?
Re-use of the 1MV post insulator developed by HITACHI for the Transmission Line
This is the reference design choice of SIEMENS. It is seen as the most natural solution and the one offering most advantages and fewer risks, especially from the overall NBPS project viewpoint:
Lower technical risk– use of proven technology (already developed and tested by HITACHI)
Efficiency, time gain – no need to re-develop from scratch an already existing product. In addition, very few units are necessary for SIEMENS (3/6 per unit depending on the design solution) compared to the production needs for the Transmission Line (approx. 40 per neutral Beam injector)
Easier maintenance, same spares
The conditions and terms of use (technical, commercial) under which such post-insulators would be supplied by HITACHI to the Project would have to be agreed between SIEMENS and HITACHI, according to HITACHI’s constraints.
In particular, considering that these post-insulators are already accepted by ITER Organization as meeting the requirements for the Transmission Line, certificates of conformity etc. may not be necessary.
The protection of HITACHI know-how on such technology should in particular be ensured, via all necessary means, to be agreed by the Parties (time at which these post-insulators would be made available with respect to the procurement schedule, prescriptions of their integration into the Interface Box etc.).
Availability outside SIEMENS
SIEMENS is also investigating the possibility to purchase such component from other manufacturers of post-insulators, either within or outside Europe.
No suitable manufacturer has been identified so far.
Availability of identical/similar product within SIEMENS
SIEMENS AG has been investigating in parallel which is the current internal capability of SIEMENSwith respect to the post-insulators required.A comprehensive portfolio of HVDC projects from SIEMENS is provided in Annex I.
The findings from this analysis are the following:
- References for HV DC applications (Plants in China, 800 kV DC) are all air-insulated which make them irrelevant for our use (gas-insulation required) – see also Annex II;
- Existing references for application with a gas insulated medium (SF6) are limited to DC 320 kV, very much below the DC voltage levels required - see also Annex III;
- A new product-line with a nominal voltage above DC 320 kV is in preparation. It remains howeverwell below the DC 1MV requested for the project of F4E (<600 kV). No further information is available on this activity (restricted commercial).
In conclusion, there is no 1 MV insulator produced by SIEMENS respectively produced by associated companies of Siemens that could be used inside the interface box.
New product development from SIEMENS
In case no other means are found a new product developmentwould have to be launched internally in SIEMENS.
Aside from the administrative considerations (heavy internal process requiring clearance from SIEMENS Top Management, difficult justification considering the limited number of units needed, possible extra costs on the project) such procurement strategy would have a direct and large impact on the schedule of the NBTF project, in particular on the Power Supply installation and integration activities.
An overall delay of more than 30 monthsis anticipated by SIEMENS under such scenario:
Specification for design, requirements – c.a. 4 months
Design and development, simulation – c.a. 16 months
Prototype and tests – c.a. 6 months
Test operation – c.a. 2 months
Closure of Final Design Report – c.a. 2 months
Conclusions
The design of the interface box (EU supply, SIEMENS) hosting the conductors transition between the HVD1 Bushing and the Connecting Piece + Transmission Line (JADA Supply, HITACHI) foresees the need to use post-insulators identical to those developed by HITACHI and used inside the Transmission Lines.
Considering that no alternative source of supply has been identified so far, and that launching the development by SIEMENS of a fit-to-purpose component would result in additional project risks, possible extra costs, and large project delays, the only suitable solution identified at this stage is to re-use the post-insulators already developed and manufactured by HITACHI for the Transmission Line.
The conditions of purchase and terms of use should be discussed and agreed between the Parties on the basis of HITACHI constraints and the project needs.
Fusion for Energy and ITER organization are in favour of such solution and willing to facilitate an agreement of the Parties to such end. A direct exchange between SIEMENS and HITACHI is also recommended at this stage, in order to progress the matter and discuss the terms of a possible agreement.
Annex I - SIEMENS brochure - HVDC - High Voltage Direct Current Transmission
See:
Annex II – Further info on Yunnan Guangdong project (800kV DC)
Yunnan Guangdong plant, 800 kV DC
Air-insulated post-insulator developed by MR and used for the Yunnan-Guangdong project
Annex III – DC compact switchgear 320 kV
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