A lightning arrester is a critical protective device designed to shield electrical insulation and conductors from damage caused by lightning surges and transient overvoltages. MS-Plus Ltd ensures that lightning arresters and complete lightning protection systems perform reliably when exposed to extreme electrical stress.
When a lightning surge travels along a power or communication line, the arrester safely diverts the excessive energy to earth, preventing thousands of kilovolts from reaching transformers, switchgear, and sensitive electronic equipment. Failure or absence of this protection can result in catastrophic equipment damage, fire hazards, and extended outages.
Surge Arrester Leakage Current Monitoring
Modern surge arresters continuously conduct a small leakage current composed of capacitive and resistive components. Many utilities monitor total leakage current; however, this method alone does not reliably indicate arrester health, as capacitive current dominates the measurement and can mask internal degradation.
The resistive component, typically 15–30% of total leakage current, is a key indicator of deterioration in zinc oxide (ZnO) discs. Even significant changes in resistive current may result in only minor variations in total current, making advanced diagnostic techniques essential.
Advanced Diagnostic Techniques
MS-Plus Ltd applies advanced monitoring methods to assess the true condition of surge arresters, including third harmonic analysis and resistive current evaluation. Leakage currents in the microampere range are generally acceptable, while rising resistive current values indicate ageing or damage.
Testing is performed while the arrester remains in service using specialised clip-on current transformers connected at the ground lead. This approach enables condition assessment without reducing system availability or compromising protection.
- Voltage reference-based analysis
- Capacitive current compensation techniques
- Three-phase leakage current comparison
- Third harmonic leakage current analysis
- Direct power loss determination
- Advanced monitoring with resistive current calculations
Lightning Protection System Testing
Lightning protection systems are often only proven effective when a strike occurs. For this reason, systematic inspection, testing, and maintenance are essential to ensure dependable performance. Lightning currents can range from 2,000 A to over 200,000 A, making system integrity critical to asset and life protection.
MS-Plus Ltd conducts inspections and testing in accordance with internationally recognised standards such as BS EN 62305. All assessments are carried out by competent, trained personnel using calibrated instruments.
Inspection and Maintenance Requirements
Visual inspections and electrical testing are carried out during installation, upon completion, and at regular intervals not exceeding 12 months. Scheduling inspections at 11-month intervals ensures the system is evaluated under varying seasonal conditions over time.
- Mechanical condition of conductors, joints, and bonds
- Integrity of earth electrodes and connections
- Verification of bonding to newly added services
- Identification of inaccessible or concealed components
- Evidence of corrosion or environmental damage
Earth Electrode Testing Methods
Accurate earth resistance testing requires expertise to avoid misleading results. MS-Plus Ltd employs proven methods such as the Fall-of-Potential (including the 61.8% method) and the Dead Earth method, selected based on site conditions and accessibility.
Where open ground is available, the Fall-of-Potential method provides precise resistance measurements using reference electrodes. In urban or restricted environments, the Dead Earth method offers a practical alternative when performed by experienced engineers.
Dead Earth Testing
Dead Earth testing measures the resistance of an electrode by referencing it against a known low-resistance earth. This method also verifies continuity across joints and bonds, highlighting any high-resistance connections that could compromise system performance.
Clamp-on testing techniques may be used where disconnection is impractical, provided site conditions allow reliable measurements.
Documentation and Compliance
Accurate record-keeping is essential for long-term system reliability. MS-Plus Ltd maintains and updates detailed inspection records to support compliance, maintenance planning, and future assessments.
- Lightning protection system drawings
- Soil and geological information
- Earth electrode locations and types
- Test conditions and measured results
- Details of repairs, upgrades, or modifications
- Responsible person or authority
Commitment to Safety
All lightning protection and earthing systems must be tested by skilled professionals using calibrated equipment. MS-Plus Ltd prioritises safety at all times, ensuring testing is never performed during storm conditions and that systems are verified as safe before disconnection.
Comprehensive lightning protection testing includes resistance measurement, continuity testing, soil resistivity assessment, and detailed visual inspections. Clients receive a clear technical report outlining findings, compliance status, and recommendations for improvement where required.