Background
Unison Contracting Services Limited, a key contractor for Aurora Energy, was selected to trial the PORTATANK® as part of Aurora Energy’s initiative to improve oil level inspections in Long & Crawford (L&C) switchgear and ABB SD Series switchgear units.
Aurora Energy operates electrical networks across the Dunedin, Central, and Queenstown regions, with Long & Crawford units exclusively installed in Dunedin and ABB SD Series oil-filled units found across all three networks.
Application: Oil Level Inspection in Switchgear
Maintaining accurate oil levels is essential for the reliable operation of a switchgear. Unison Contracting Services Limited was tasked with improving the efficiency and accuracy of oil level inspections on Aurora Energy’s network. Traditional methods, such as dipsticks, were time-consuming and had potential limitations in accuracy, requiring a more reliable, non-invasive ultrasonic solution.
Challenges Faced
- Existing manual methods were inefficient, requiring direct access to the oil reservoir.
- Dipstick readings were time-consuming and subject to human error.
- Ensuring accurate and repeatable oil level measurements was difficult across different switchgear models.
- Switchgear units required non-invasive inspection solutions that could function while systems remained live.
The PORTATANK® Solution
On 9th July 2024, a training and trial session was conducted at Unison’s workshop in collaboration with Aurora Energy. The session was led remotely by Coltraco Ultrasonics’ technical team, including Technical Director Adrian Saw and Technical Sales Engineer Leah Joyce Lucmayon.
The PORTATANK® was used to identify oil levels in:
✔ Long & Crawford (L&C) switchgear models: T4GF3, J4, GF3
✔ ABB SD Series switchgear units
The PORTATANK® operates by scanning the side walls of the switchgear tank using ultrasonic sensors. When the sensor detects oil, an LED indicator lights up, providing a clear and immediate reading. The correct parameters were easily set up, ensuring accuracy. An oscilloscope is also available for troubleshooting if needed.
Successful Trial & Positive Results
Following the ultrasonic test, Unison confirmed the accuracy of the PORTATANK® readings using dipstick measurements, validating the device’s performance. The results showed:
🔹 High accuracy and reliability in detecting oil levels across all tested switchgear units.
🔹 Seamless configuration and user-friendly setup, requiring minimal training.
🔹 Time-saving and efficient inspection process, improving operational workflows.
The session received overwhelmingly positive feedback from Unison, with the team experiencing no difficulties in setting up parameters or conducting the test.
Benefits of PORTATANK®:
Non-invasive methods for verifying oil levels in switchgear offer a safer, faster, and more efficient alternative to traditional methods like dipsticks and sight glasses. Conventional methods often require opening the switchgear, which exposes personnel to electrical hazards and risks contamination of the oil. In contrast, ultrasonic technology enables oil level detection without opening the unit, eliminating safety risks and ensuring compliance with operational safety protocols.
Manual inspections are also time-consuming and prone to human error. Dipsticks require physical access and interpretation, while sight glasses may become dirty, obscured, or inaccurate over time. In contrast, non-invasive ultrasonic devices provide instant, precise, and repeatable measurements, significantly improving accuracy and reducing maintenance downtime.
Additionally, switchgear is often located in confined spaces or high-voltage areas, making physical inspections challenging. A non-invasive approach allows operators to measure oil levels externally, reducing the need for specialized training or equipment shutdowns.
By using non-invasive methods, utilities and maintenance teams can increase efficiency, minimize downtime, and enhance worker safety while ensuring switchgear remains in optimal condition. The ability to conduct quick, routine inspections without disassembly ultimately leads to better asset management and extended equipment lifespan.
Conclusion: A Pathway to Wider Adoption
The PORTATANK® trial demonstrated its effectiveness in non-invasive oil level detection for switchgear maintenance. Aurora Energy is now expected to recommend the deployment of PORTATANK® across its three networks (Dunedin, Central, and Queenstown) for switchgear and transformer inspections.
With its ability to detect oil levels in vessels ranging from 0.5m to 15m in diameter, even while systems remain live, the PORTATANK® provides a reliable, efficient, and cost-effective solution for contractors working with switchgear and transformers worldwide.
Please download the document to read the case study in full which has been approved both Aurora Energy, New Zealand and Unison Contracting Services Limited.
