Condition monitoring system installation in Korean substations covers the transformer and GIS monitoring units that watch sensor signals from main transformers and gas-insulated switchgear in real time, store and analyze the data, and flag signs of trouble. Substation maintenance has moved from repair after failure, through time-based inspection, to condition-based maintenance that acts when equipment condition calls for it — and this system is what makes that possible. This guide covers two stages: transformer monitoring and GIS monitoring.
Contents
- Common Pre-Work Review
- 1. Transformer Monitoring
- 2. GIS Monitoring
- Monitoring System Components
- FAQ
- Reference Standards
- Summary
Common Pre-Work Review
Review the manufacturer’s layout drawings, power and I/O wiring diagrams, software guide and the client’s monitoring installation standard. The system consists of an HMI server, coaxial cable, a main unit (server), local units (DAU, CU) and sensors. Confirm communication follows IEC 61850 (TCP/IP), and prepare partial discharge test equipment and a torque wrench. Workers wear insulated helmets, flame-resistant clothing, insulated boots and harnesses, and carry proximity alarms.
1. Transformer Monitoring
- Review the architecture of the substation monitoring system and the function of each device.
- Check manufacturer drawings, assembly drawings and operating manuals.
- Install the transformer monitoring unit and sensors and connect signal wiring.
- Commission online, linked with the monitoring software.
Transformer monitoring can cover acoustic and UHF partial discharge, combustible gases, leakage current, OLTC operating data, moisture, cooling pumps and fans, oil and winding temperature and load current. Dissolved gases are chosen from H₂, CH₄, C₂H₂, C₂H₄, C₂H₆, CO, CO₂ and TDCG; common systems include Hydran (combustible gas) and Calisto AMS (dissolved hydrogen).
2. GIS Monitoring
- Review the contractor’s installation drawings, manuals and diagnostic software.
- Check internal and external sensor positions on the GIS, with overlapping coverage.
- Install the GIS monitoring unit, partial discharge (PD) sensors and noise sensors, and connect signal wiring.
- Measure noise around the equipment and plan shielding.
- Carry out online adjustment tests across the whole PD system.
Measure the substation’s noise environment and apply shielding before installation to reduce false alarms.
Monitoring System Components
| Component | Role |
|---|---|
| Sensors (UHF, acoustic, etc.) | Detect UHF emissions or sound from partial discharge; GIS sensors are internal (in tank) or external |
| Local unit (DAU, CU) | Amplifies sensor signals and converts them to optical signals for the main unit |
| Main unit | Collects local unit signals and sends them to the analysis server |
| HMI server | Shows operators whether PD is present, its type and magnitude |
| Local LCD and laptop | Real-time waveforms and events; data storage |
Related standards include KS C 3700 (UHF PD measurement), KS C 2301/2101 (oil analysis and tests), IEC 61000 (EMC) and IEC 61850 (communications).
FAQ
What does the system monitor?
It receives transformer and GIS sensor signals in real time and analyzes changes in partial discharge, dissolved gas, temperature and leakage current to flag abnormalities.
How are GIS partial discharge sensors installed?
They detect UHF emissions from partial discharge and are either internal (inside the tank) or external. Place them so coverage overlaps.
Why measure noise first?
Ambient electromagnetic noise can be mistaken for partial discharge and cause false alarms, so measure it and plan shielding before installing.
Reference Standards
- Electricity Business Act (전기사업법) — law.go.kr
- Electrical Safety Management Act (전기안전관리법) — law.go.kr
- Electric Technology Management Act (전력기술관리법) — law.go.kr
- Electrical Construction Business Act (전기공사업법) — law.go.kr
- Occupational Safety and Health Act (산업안전보건법) — law.go.kr
- Korea Electro-technical Code (KEC, 한국전기설비규정) — law.go.kr
- Technical Standards for Electrical Equipment (전기설비기술기준) — law.go.kr
- KEPCO design standards and substation construction practice; Korean Industrial Standards (KS)
- NCS competency unit Substation Condition Monitoring System Installation (예방진단시스템 설치공사, 1901070316_22v2; NCS is Korea’s National Competency Standards) — ncs.go.kr
Summary
The most common mistakes are installing sensors without measuring noise, leading to frequent false alarms, and leaving blind spots between sensor coverage zones. Transformer monitoring depends on choosing diagnostic items and commissioning with the software; GIS monitoring on sensor layout, noise measures and online adjustment tests. Related guides: Main Transformer Maintenance, Switchgear Overhaul Maintenance, Digital Substation System Installation. A Korean version of this guide is available here.
This article restructures the Korean NCS competency unit ‘Substation Condition Monitoring System Installation’ (예방진단시스템 설치공사, code 1901070316_22v2) as a practical reference. Actual work must follow applicable standards and the judgment of qualified professionals; always confirm specific values, deadlines and criteria against the latest regulations and client standards.
Written/reviewed by VOLT · Last updated 2026-10-26