Efficient and Effective

Vertical Transition Straight Joints Innovative Inspection (Cable Canary)

Project Data

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The project will develop an innovative device called “Cable Canary” that will define the bandwidth at which HV cable joints fail. It wil use partial discharge technology to detect a potential failure within the HV joints and alarm before its failure.

What is the project about?

When 11kV switchgear changes in the LPN area were planned, consideration within the budget for excavation and reinstatement in the adjacent footway had to be made. This activity added a considerable amount of money to the budget required for each switchgear change and, in 1996, the decision was made to install these joints inside the sub-station in a vertical position adjacent to the switch-gear. There are approximately 4,000 sites in the LPN area containing these joints; there are generally 2 joints per site.

The aim of the project is to successfully develop an innovative product that can monitor the health of HV cable joints and identify those at higher risk of failure for their controlled replacement

How we’re doing it

Partial Discharge (PD) readings on existing VTSJs will be captured through undertaking site inspections at substation sites within the LPN area of UK Power Networks using the PD Hawk device. If and when a defective joint(s) is found, the joint sample will be retrieved for forensic analysis in the laboratory at EA Technology. Following the PD data capturing exercise and laboratory analysis of joint sample(s) retrieved, a new product “Canary” will be developed which will specify a bandwidth of partial discharge at which joints are likely to fail.

The Canary is planned to be a mobile device that can be fixed at site for a chosen period, therefore an enhancement to the existing handheld PD Hawk device that is used at a given time of day at the point of inspection. This will provide the ability to monitor PD readings overtime which may lead to improved detection of PD failure modes and subsequently improved identification of sites at higher risk of failure for controlled replacement.

What makes it innovative

Research and development will be carried out to develop a portable device for the detection of partial discharge from an HV cable joints within substaitons. Unlike complex and expensive mains borne signalling devices which are designed and built for a specific type of plant equipment, this device is portable and can be used within a sub-station site, is innovative and specifically designed for HV cable joints.

There is no other simple partial dischange device available that is able to be interrogated on-site to give an immediate assessment of partial discharge. The VSJ blanket was developed specifically for use on joints to provide protection to people, property and plant in the event of a failure.

What we’re learning

The project will demonstrate specified thresholds identified for HV cable joint failure can be used to alarm for a potential failure within HV cable joints.

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