Automated Monitoring Delivers Fast, Accurate Data for Tower Inspections

Author: Özgür AVCI, Ruth Badley, Megan Hansen

Interruptions to the electricity supply negatively impact everyone from domestic consumers and businesses to the wider economy. To minimise the risk of potentially dangerous and costly power failures, it is crucial to rigorously monitor the mechanical strength and stability of poles and towers used for energy transmission and other essential services.

Leica Geosystems’ fully automated monitoring solutions help enable design verification and strength testing for the MİTAŞ Group’s electric tower inspections in Turkey. The combination of Leica Geosystems’ geodetic sensors, third party geotechnical sensors, and advanced Leica GeoMoS deformation monitoring software provides high-accuracy measurements and fast analysis, allowing test engineers to observe 3D movements in real-time during load tests.

Tower Inspections to International Quality Control Standards

The MİTAŞ Group in Turkey is a world leader in the design, production, galvanisation, and assembly of power transmission line towers. By opening their own tower testing facility, MITAŞ’ industry experience and expertise now covers the complete supply chain, from raw material to manufacture, through to testing and supplying the final product.

The ENA Tower Testing Station Inc. (ENA), part of the MİTAŞ Group, specialises in full-scale strength testing of towers used in energy transmission. Particularly, the pylons supporting high voltage power cables are tested to international standards, both to verify the design of these critical structures and to detect possible manufacturing errors.

To comply with international quality control standards, towers are subjected to two types of displacement tests - the Design Test and the Sample Test. Testing procedures are defined by the highest international standards, including ASCE 10-97, ASCE Manual 52, IEC 60652, IS802 Part III. ENA established and implemented the quality system set out in ISO IEC 17025 and carries out their inspections in accordance with the regulatory standard EN IEC 60652.

During the Design Test, towers are gradually subjected to the highest loads they will carry during their service life. The mechanical strength of a tower is expected to be stronger than the conductor loads it will carry and it must also withstand the impact of maintenance, repair, and extreme weather conditions. By testing towers until the point of destruction, engineers can identify areas for design, manufacture, and assembly improvements at an early stage. In the Sample Test, random towers are selected from a production batch for exposure to design loads to verify the quality and strength required for a project.

Electric tower testing by ENA Tower Testing Station, part of the MİTAŞ Group

Techniques for Tower Inspections and the Challenges of Manual Measurements

Traditionally, measuring manually by intersection involves two theodolites or total stations positioned perpendicular to each other to take angle readings to the top, middle, and lowest points of multiple levelling staffs mounted on the towers. 2D displacements (longitudinal and transverse) of the staff and the tower can be calculated by periodically reading the same point on the staff from two total stations.

This measurement method is time consuming and can be inaccurate due to changing environmental conditions. Measuring the highest staff with the total station is challenging and prone to error as the surveyor must aim the instrument accurately at a steep vertical angle within a defined time interval to correlate displacement data with geotechnical sensors, and then transfer the readings to a central office for analysis.

Overcoming the Challenges with a Real-Time Automated Monitoring Solution

To meet the increasing demand from utility companies for specialist testing, service providers are moving from the manual methods of the past to fully automated, integrated monitoring solutions for fast, high-accuracy displacement analysis.

With advice and support from Sistem A.Ş., Leica Geosystems’ representatives in Turkey, ENA has replaced manual measurement methods with a state-of-the-art automated monitoring solution that delivers faster, accurate load test data every time.

The solution includes a Leica TS16 robotic total station measuring Leica GMP104 L mini prisms mounted at specified points on the tower. GMP104 L prisms are designed for monitoring, easy to mount, and feature special coatings that enable the Leica total stations to achieve the highest measurement accuracy specifications – making the choice of a Leica original prism important for the best possible results.

Initially, GeoMoS records and stores the prism coordinates measured by the total station and then instructs the instrument to repeat the measurement based on the last known position of the prisms. This ‘learning’ of the last successful measurement makes the process quick, reliable, and accurate as the TS16’s Automatic Target Recognition (ATR) technology aims to the centre of the prism to measure a new position.

All data is processed by GeoMoS Monitor with displacements calculated automatically. Cross-checking with geotechnical sensors is performed via Leica GeoMoS Now!, the web-based visualisation and reporting platform. A multi-language interface, including Turkish, displays graphics and numerical value tables, with all the data accessible to senior engineers for analysis immediately after each measurement, both onsite and remotely.

Reliable Real-Time Test Results

Instantly sharing load test data with all stakeholders has positively impacted both quality assurance and efficiency. Emre Kilinc, ENA’s towering testing engineer commented, Leica Geosystems’ automated solution and the real-time results it delivers gives our customers absolute confidence in our processes. As ENA uses several types of monitoring sensors simultaneously, to be able to see and understand 3D movements of the towers during load tests effectively means we can collect, process and analyse more data in a fraction of the time it would take using manual methods.

Özgür Avci, NRS & GeoMoS Division Manager at Sistem A.Ş. worked closely with ENA’s engineers at every stage, from product selection and design methodology, through to training and onsite support to establish the new workflow.

Emre Kilinc commented, The set up was quick and easy as the prisms are easily fitted on the tower, either with a screw or magnetic mount. It took only a little training to be confident with the automated solution – it really looks after itself - and we are grateful for the support provided by Sistem A.Ş. and for advice during the first few tests.

Replacing manual methods with an automated monitoring solution comprising a Leica total station and GeoMoS software has streamlined the monitoring process for tower inspection. ENA saves time, work hours, and costs, whilst also improving quality assurance as the automated system eliminates error risks. Load tests are reliable and data-rich with displacement results available to decision-makers in real-time. 

Interested in monitoring? Please feel free to read further case studies, showing how our customers use our solution to improve their monitoring workflow:

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