Eptra - electric power transmission :: Kilian Schillai
electric power transmission engineering endurance & reliability

Eptra Engineering

We are specialised in solutions in the area of electrical power transmission, especially in mechanical aspects and long-term reliability. As a spin-off of the Swiss Federal Laboratories for Materials Science and Technology (Empa) and ETH Zürich, we have experience in the modelling and calculation of damage mechanisms of the relevant materials and continue to foster cooperation with the scientific community.

In damage cases, it is essential to determine the root cause in a failure analysis in order to avoid recurring damage. With a combination of damage/fracture pattern analysis, material analysis (mechanical properties, metallography, composition), simulations, and reproduction of the damage in laboratory tests, the cause of damage usually can be determined unambiguously. Our expertise is centred around the particular problems of materials and components for electrical power transmission.

Major parts of the grid are more than 50 years old. The materials, designs, and processes used in the past differ considerably from the current state of technology, so that the application of today's design methods and fittings can lead to damage. With our analytical techniques we help to develop and review procedures for condition assessment and preventive maintenance in the asset management.

Often the damage mechanisms, such as the progressive loss of strength at temperature, the reduction of the clamping force and increased contact resistance due to creep, and fatigue are very long-term effects. In material and especially in component tests (e.g. type tests), modelling the material behaviour is often unavoidable. We are happy to contribute our experience with accelerated ageing in the laboratory and procedures for fault testing (defect screening) in the laboratory to the testing of your components and fittings.

We are equipped for the experimental measurement and the modelling of material parameters as input data for simulations. For example, we are able to test tensile strength and plastic deformation at room and maximum operating temperature, creep and fatigue on single wires as well as whole conductors or components. With our experience in test stand development, especially for component and conductor/cable tests, we also support the rapid and reliable expansion of your own test capacities.

Mechanical and thermal analysis with finite element simulations, modelling and testing are the backbone of our work. With our experience in material modelling, simulation, accelerated ageing and component testing, we are happy to support you in your product development.

News

Defects in a cast iron power transmission component:

Different power transmission components made of nodular cast iron failed in service, in some cases after many years of operation. Metallographic cross sections revealed different material defects as the cause.

Edge hardness led to glass-like brittle behaviour (cementite needles and ledeburite, left), the coarse graphite and inhomogeneous microstructure lead to lack of strength (right). To prevent further damage, among other things, the material specification and geometry were changed and measurements were introduced to monitor incoming components.

>Further information on failure analysis of electric power transmission components<

 

Influences on conductor fatigue and limits in current design procedures:

Local finite element model

Global finite element model

In our contribution to the last Cigre conference, we investigated the influence of a variety of geometry, material and load parameters on the fatigue strength of overhead line conductors under wind-excited vibrations and tested the limits of current design methods. Two different types of finite element models were used, a local model to evaluate stresses at failure locations and a global model in which multiple spans were simulated. A key result is the change in local stresses at the failure location (amplitude, mean stress and their combination) relative to a reference case common in Switzerland (AAAC 550 in commercial suspension clamp). The type of suspension of the fittings has a great influence on the fatigue strength. A rotation axis in the centre of the conductor is optimal; the stresses are even lower only if the conductor is unloaded on one side (e.g. at end clamps).

The significantly better fatigue performance of ACSRs (Aluminium Conductors Steel Reinforced, consisting of a steel core and pure aluminium in the outer layers) compared to AAACs (All Aluminium Alloy Conductors, in Europe almost exclusively made of an E-AlMgSi alloy) cannot be explained by different local stresses alone, but the material properties of the aluminium play a crucial role. The core material, on the other hand, has relatively little influence on the local mechanical loads. Because of the inherent scatter, such information can hardly be derived experimentally without simulations.

Current design methods do not take into account important parameters such as the geometry and suspension of fittings, or do so insufficiently. Therefore, it is important that such parameters are tested by the fitting manufacturers.

Original publication: "Limits of vibration amplitude measurement based conductor fatigue design", Cigre E-Session 2020; paper available as PDF and presentation as video.

>Further information on our services for simulations and measurements<

Privacy Statement

Privacy Policy

1. An overview of data protection

General information

The following information will provide you with an easy to navigate overview of what will happen with your personal data when you visit this website. The term “personal data” comprises all data that can be used to personally identify you. For detailed information about the subject matter of data protection, please consult our Data Protection Declaration, which we have included beneath this copy.

Data recording on this website

Who is the responsible party for the recording of data on this website (i.e., the “controller”)?

The data on this website is processed by the operator of the website, whose contact information is available under section “Information about the responsible party (referred to as the “controller” in the GDPR)” in this Privacy Policy.

How do we record your data?

We collect your data as a result of your sharing of your data with us. This may, for instance be information you enter into our contact form.

Other data shall be recorded by our IT systems automatically or after you consent to its recording during your website visit. This data comprises primarily technical information (e.g., web browser, operating system, or time the site was accessed). This information is recorded automatically when you access this website.

What are the purposes we use your data for?

A portion of the information is generated to guarantee the error free provision of the website. Other data may be used to analyze your user patterns.

What rights do you have as far as your information is concerned?

You have the right to receive information about the source, recipients, and purposes of your archived personal data at any time without having to pay a fee for such disclosures. You also have the right to demand that your data are rectified or eradicated. If you have consented to data processing, you have the option to revoke this consent at any time, which shall affect all future data processing. Moreover, you have the right to demand that the processing of your data be restricted under certain circumstances. Furthermore, you have the right to log a complaint with the competent supervising agency.

Please do not hesitate to contact us at any time if you have questions about this or any other data protection
related issues.

2. Hosting and Content Delivery Networks (CDN)

External Hosting

This website is hosted by an external service provider (host). Personal data collected on this website are stored on the servers of the host. These may include, but are not limited to, IP addresses, contact requests, metadata and communications, contract information, contact information, names, web page access, and other data generated through a web site.

The host is used for the purpose of fulfilling the contract with our potential and existing customers (Art. 6 para. 1 lit. b GDPR) and in the interest of secure, fast, and efficient provision of our online services by a professional provider (Art. 6 para. 1 lit. f GDPR).

Our host will only process your data to the extent necessary to fulfil its performance obligations and to follow our instructions with respect to such data.

We are using the following host:

Mittwald CM Service GmbH & Co. KG
Königsberger Straße 4-6
32339 Espelkamp

Execution of a contract data processing agreement

In order to guarantee processing in compliance with data protection regulations, we have concluded an order processing contract with our host.

3. General information and mandatory information

Data protection

The operators of this website and its pages take the protection of your personal data very seriously. Hence, we handle your personal data as confidential information and in compliance with the statutory data protection regulations and this Data Protection Declaration.

Whenever you use this website, a variety of personal information will be collected. Personal data comprises data that can be used to personally identify you. This Data Protection Declaration explains which data we collect as well as the purposes we use this data for. It also explains how, and for which purpose the information is collected.

We herewith advise you that the transmission of data via the Internet (i.e., through e-mail communications) may be prone to security gaps. It is not possible to completely protect data against third-party access.

Information about the responsible party (referred to as the “controller” in the GDPR)

The data processing controller on this website is:

Eptra Engineering
Kilian Schillai
Am Stadtrand 31
8600 Dübendorf

Phone: +41 76 652 5116
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

The controller is the natural person or legal entity that single-handedly or jointly with others makes decisions as to the purposes of and resources for the processing of personal data (e.g., names, e-mail addresses, etc.).

Storage duration

Unless a more specific storage period has been specified in this privacy policy, your personal data will remain with us until the purpose for which it was collected no longer applies. If you assert a justified request for deletion or revoke your consent to data processing, your data will be deleted, unless we have other legally permissible reasons for storing your personal data (e.g., tax or commercial law retention periods); in the latter case, the deletion will take place after these reasons cease to apply.

Revocation of your consent to the processing of data

A wide range of data processing transactions are possible only subject to your express consent. You can also revoke at any time any consent you have already given us. This shall be without prejudice to the lawfulness of any data collection that occurred prior to your revocation.

Right to object to the collection of data in special cases; right to object to direct
advertising (Art. 21 GDPR)

IN THE EVENT THAT DATA ARE PROCESSED ON THE BASIS OF ART. 6 SECT. 1 LIT. E OR F GDPR, YOU HAVE THE RIGHT TO AT ANY TIME OBJECT TO THE PROCESSING OF YOUR PERSONAL DATA BASED ON GROUNDS ARISING FROM YOUR UNIQUE SITUATION. THIS ALSO APPLIES TO ANY PROFILING
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YOUR DATA, THAT OUTWEIGH YOUR INTERESTS, RIGHTS AND FREEDOMS OR IF THE PURPOSE OF THE PROCESSING IS THE CLAIMING, EXERCISING OR DEFENCE OF LEGAL ENTITLEMENTS (OBJECTION PURSUANT TO ART. 21 SECT. 1 GDPR).

IF YOUR PERSONAL DATA IS BEING PROCESSED IN ORDER TO ENGAGE IN DIRECT ADVERTISING, YOU HAVE THE RIGHT TO AT ANY TIME OBJECT TO THE PROCESSING OF YOUR AFFECTED PERSONAL DATA FOR THE PURPOSES OF SUCH ADVERTISING. THIS ALSO APPLIES TO PROFILING TO THE EXTENT THAT IT IS AFFILIATED WITH SUCH DIRECT ADVERTISING. IF YOU OBJECT, YOUR
PERSONAL DATA WILL SUBSEQUENTLY NO LONGER BE USED FOR DIRECT ADVERTISING PURPOSES (OBJECTION PURSUANT TO ART. 21 SECT. 2 GDPR).

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In the event of violations of the GDPR, data subjects are entitled to log a complaint with a supervisory agency, in particular in the member state where they usually maintain their domicile, place of work or at the place where the alleged violation occurred. The right to log a complaint is in effect regardless of any other administrative or court proceedings available as legal recourses.

Right to data portability

You have the right to demand that we hand over any data we automatically process on the basis of your consent or in order to fulfil a contract be handed over to you or a third party in a commonly used, machine readable format. If you should demand the direct transfer of the data to another controller, this will be done only if it is technically feasible.

SSL and/or TLS encryption

For security reasons and to protect the transmission of confidential content, such as purchase orders or inquiries you submit to us as the website operator, this website uses either an SSL or a TLS encryption program. You can recognize an encrypted connection by checking whether the address line of the browser
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If the SSL or TLS encryption is activated, data you transmit to us cannot be read by third parties.

Information about, rectification and eradication of data

Within the scope of the applicable statutory provisions, you have the right to at any time demand information about your archived personal data, their source and recipients as well as the purpose of the processing of your data. You may also have a right to have your data rectified or eradicated. If you have questions about this subject matter or any other questions about personal data, please do not hesitate to contact us at any time.

Right to demand processing restrictions

You have the right to demand the imposition of restrictions as far as the processing of your personal data is concerned. To do so, you may contact us at any time. The right to demand restriction of processing applies in the following cases:

  • In the event that you should dispute the correctness of your data archived by us, we will usually need some time to verify this claim. During the time that this investigation is ongoing, you have the right to demand that we restrict the processing of your personal data.
  • If the processing of your personal data was/is conducted in an unlawful manner, you have the option to demand the restriction of the processing of your data in lieu of demanding the eradication of this data.
  • If we do not need your personal data any longer and you need it to exercise, defend or claim legal entitlements, you have the right to demand the restriction of the processing of your personal data instead of its eradication.
  • If you have raised an objection pursuant to Art. 21 Sect. 1 GDPR, your rights and our rights will have to be weighed against each other. As long as it has not been determined whose interests prevail, you have the right to demand a restriction of the processing of your personal data.

If you have restricted the processing of your personal data, these data – with the exception of their archiving – may be processed only subject to your consent or to claim, exercise or defend legal entitlements or to protect the rights of other natural persons or legal entities or for important public interest reasons cited by
the European Union or a member state of the EU.

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In some cases, it is possible that third-party cookies are stored on your device once you enter our site (thirdparty cookies). These cookies enable you or us to take advantage of certain services offered by the third party (e.g., cookies for the processing of payment services). Cookies have a variety of functions. Many cookies are technically essential since certain website functions would not work in the absence of the cookies (e.g., the shopping cart function or the display of videos). The purpose of other cookies may be the analysis of user patterns or the display of promotional messages.

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You have the option to set up your browser in such a manner that you will be notified any time cookies are placed and to permit the acceptance of cookies only in specific cases. You may also exclude the acceptance of cookies in certain cases or in general or activate the delete function for the automatic eradication of cookies when the browser closes. If cookies are deactivated, the functions of this website may be limited.

In the event that third-party cookies are used or if cookies are used for analytical purposes, we will separately notify you in conjunction with this Data Protection Policy and, if applicable, ask for your consent.

Cookie Consent with Usercentrics

This website uses the cookie consent technology of Usercentrics to obtain your consent to the storage of certain cookies on your device or for the use of specific technologies, and to document the former in a data protection compliant manner. The party offering this technology is Usercentrics GmbH, Rosental 4, 80331 München, Germany, website: https://usercentrics.com/ (hereinafter referred to as “Usercentrics”).

Whenever you visit our website, the following personal data will be transferred to Usercentrics:

  • Your declaration(s) of consent or your revocation of your declaration(s) of consent
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Moreover, Usercentrics shall store a cookie in your browser to be able to allocate your declaration(s) of consent or any revocations of the former. The data that are recorded in this manner shall be stored until you ask us to eradicate them, delete the Usercentrics cookie or until the purpose for archiving the data no longer exists. This shall be without prejudice to any mandatory legal retention periods.

Usercentrics uses cookies to obtain the declarations of consent mandated by law. The legal basis for the use of specific technologies is Art. 6 Sect. 1 Sentence 1 lit. c GDPR.

Contract data processing agreement

Our company has executed a Contract Data Processing Agreement with Usercentrics. This is an agreement mandated by data privacy protection legislation that warrants that Usercentrics processes all personal data of our website visitors exclusively in compliance with our instructions and in compliance with the GDPR.

Request by e-mail, telephone, or fax

If you contact us by e-mail, telephone or fax, your request, including all resulting personal data (name, request) will be stored and processed by us for the purpose of processing your request. We do not pass these data on without your consent.

These data are processed on the basis of Art. 6 Sect. 1 lit. b GDPR if your inquiry is related to the fulfillment of a contract or is required for the performance of pre-contractual measures. In all other cases, the data are processed on the basis of our legitimate interest in the effective handling of inquiries submitted to us (Art. 6 Sect. 1 lit. f GDPR) or on the basis of your consent (Art. 6 Sect. 1 lit. a GDPR) if it has been obtained.

The data sent by you to us via contact requests remain with us until you request us to delete, revoke your consent to the storage or the purpose for the data storage lapses (e.g. after completion of your request). Mandatory statutory provisions - in particular statutory retention periods - remain unaffected.

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Contact

For a one-on-one conversation, I am available to you via phone (+41 76 652 5116) or email (This email address is being protected from spambots. You need JavaScript enabled to view it.). I look forwards to hearing from you.

 

Eptra Engineering GmbH
Dr. Kilian Schillai

Am Stadtrand 31 
CH-8600 Dübendorf
+41 76 652 5116
This email address is being protected from spambots. You need JavaScript enabled to view it.

Legal Notice

Eptra Engineering
Dr. Kilian Schillai

Am Stadtrand 31 
CH-8600 Dübendorf
This email address is being protected from spambots. You need JavaScript enabled to view it.
+41 76 652 5116

About us

After many years in research on the ageing of energy infrastructure at the Swiss Federal Laboratories for Materials Science and Technology (Empa) and ETH Zurich, I now support the practical improvement of reliability issues, especially in electrical power transmission. The focus of my work is on testing and optimisation of mechanical, thermal and electrical aspects in simulation and measurement.
As a small business, we can adapt flexibly to your needs and are open to a broad variety of projects in terms of duration, type and scope.

For a one-on-one conversation, I am available to you via phone (+41 76 652 5116) or email (This email address is being protected from spambots. You need JavaScript enabled to view it.). I look forwards to hearing from you.