Mainline Power has the capability to install and joint cables from 20KV to 220KV. Unlike other cable installers we are unique in that the cable installation and jointing, as well as the testing (see Testing Section) is carried out in-house. For you the customer this means that Mainline Power will complete the project with experienced personnel, whom we know can deliver a quality product. We are approved by ESB Networks to install/joint cables up to 220KV.
Mainline Power provides a full underground cable duct design and installation service. We will ensure that the optimum duct type and size is installed to ensure that cable pulling tensions are within cable manufacturers guidelines while ensuring that future electrical losses are kept to a minimum.
We have over fourteen years experience in the new-build, and refurbishment of HV / MV substations with ESB, as well as within the private sector. We also carry out major refurbishment programmes for the ESB in live substations. The type of work we have completed to date includes the following:
• 110 KV Station refurbishment and protection upgrade.
• 110 KV Cubicle installation and upgrade including all civil works.
• 110 KV Islanding protection.
• 110 KV Bulk Supply Metering.
• 110/38/20 KV Duct & Cable installation and jointing.
• 20 KV Sub-station installation, maintenance and commissioning, & civil works.
• 38 KV Sub-station Design, Build and Commission.
• 38 KV Traffo Installation and Differential and Neutral Earth Fault protection upgrade.
• 38 KV Sub-station Refurbishment including all civil works.
• 38 KV Protection upgrade including build/supply protection panels.
• 38 KV Asset replacement.
• Auto-Recloser installation, testing and commissioning.
Mainline Power has the in-house capability to carry out all associated electrical testing for HV, MV and LV installations, including Particle Discharge Testing (PD), Very Low Frequency Testing (VLF), and Tan Delta Testing (TD).
The objective of any testing, whether it is carried out as part of the commissioning procedure, or as part of a preventative maintenance programme, is to maximise the reliability, and lifespan of the installation. Typically, the conversion of defects into faults starts with the initiation of a discharge at the fault location, as the cable is put under electrical stress. This leads to electrical tree growth in the cable dielectric and ultimately to a breakdown of the cable insulation. By using the above mentioned testing techniques, we can detect and monitor the following:
• Degradation of the cable and cable joint insulation.
• Mechanical damage to the cables and cable joints.
• Monitor ongoing condition of the cable (periodic testing).
• Assess suitability of the existing cable joints and termination kits.
• Pinpoint the location of potential future failure points.
Click here for further information on the benefits of using our market leading b2 testing equipment
Very Low Frequency (VLF) insulation Testing (or withstands tests) is usually carried out at 0.1 Hz and involves applying a test voltage of three times the nominal working voltage to the cable for one hour, or 15 minutes for older cables. VLF Testing takes longer to perform than DC insulation resistance testing, but will more reliably uncover a wider range of problems, and is less likely to cause further damage to the cable, especially older cables, enabling electrical apparatus to be better classified as either good for return to service (Go) or susceptible to imminent failure (No Go). Accordingly therefore VLF Testing provides an accurate snapshot of the functional status of a cable at a point in time (Go/No Go), but does provide an indication of possible future issues.
SMART VLF Testing: Tan Delta Testing (see below) can also be combined with VLF testing to provide an intelligent or SMART VLF Test. By analysing the Tan Delta information in real time, the Test Engineer can reduce the frequency of testing on cables which demonstrate good characteristics, and increase the frequency of testing on cables which demonstrate poor insulation characteristics
Tan Delta (TD) Testing, also referred to as Loss Angle or the Dissipation Factor Testing, is an excellent diagnostic criteria that provides an indication of the quality of the dielectric insulation, by analysing the dielectric losses in the insulation. The TD Test provides a versatile high voltage diagnostic system that is suitable for testing MV and HV cables, as well as other electrical apparatus such as capacitors, transformers and large rotating machines. Essentially with the Tan Delta Test insulation defects can be detected before they result in the ultimate failure of the equipment.
Tan Delta measurements are the most effective and widely used diagnostic method for detecting water trees and water degradation, the most common aging mechanism and cause of failure in old extruded insulated cables, which often go undetected with other common diagnostic techniques. Tan Delta tests can also be performed at test voltages below the normal operating voltage of the equipment under test, which minimizes the risk of a cable insulation failure, which could otherwise occur during an elevated voltage test, on a weak or old cable.
Small particles, such as dust, tiny trace substances, humidity or minute air gaps, can sometimes go undetected during the installation process, and if they are in a critical location, they can cause defects. This can lead to severe insulation failures and a reduction in the lifetime of the cable. Such subtle defects may not always be detected during a VLF Test, however they can be detected by Partial Discharge (PD) Testing, allowing an assessment of the future operational reliability of the equipment. With PD Testing it is therefore possible to categorized cables as “new”, “strongly aged” or “faulty”, thus enabling appropriate maintenance and repair measures to be planned and organised in advance. PD measurements are consequently the established diagnostic criteria used to access the majority of electrical equipment in a power system, and more importantly the quality to which that equipment was installed.
The 1st graphic below shows the individual benefit of VLF, TD and PD Testing, all three methods of testing provide useful information, but different information. The graphic also demonstrates that no single test is sufficient to fully analyse the operational reliability of the equipment under test.
The 2nd graphic below clearly demonstrates the benefits of a combined testing regime and accordingly Mainline Power recommends that where appropriate, all testing programmes include VLF, TD and PD Testing to ensure the full extent of the operational reliability of the equipment under test is ascertained. Mainline Power has the in-house capability to carry out VLF, TD and PD Testing.
Mainline Power also has the capability to carry out duct installation, as well as all civil works associated with MV/HV substation new-build and refurbishment including the following:
• Construction of bunded transformer bases.
• Complete compound civil works and construction of MV/HV switchgear buildings and relay rooms.
• Installation of line Cubicle bases, ducting, surfacing of compounds and erection of compound fencing and support structures.