KAIST NUCLEAR QAUNTUM Survey on Electrical Faults in

KAIST NUCLEAR & QAUNTUM Survey on Electrical Faults in the Nuclear Power Plants Young Seung LEE 03/07/2005 SEMINAR NICIEL SEMINAR 1 / 19

Table of Contents • • KAIST NUCLEAR & QAUNTUM Introduction Fault Analyses of Nuclear Power Plants Electrical Faults by Cases Electrical Preventive Maintenance Summary Further Study Reference NICIEL SEMINAR 2 / 19

Introduction l Electricity § One of our most widely used forms of energy. § No mass storage. § Electrical faults at equipment spread over power system, because components are connected through wires. l Electrical Hazards § Electric shock § Fires and explosions l KAIST NUCLEAR & QAUNTUM Electrical Fault in Power Plants § § Power outages are a tremendous loss. Fault analyses of power plants are necessary to reduce outages. NICIEL SEMINAR 3 / 19

Fault Analyses in Nuclear Power Plants KAIST NUCLEAR & QAUNTUM l Trip Causes of NPPs(2000~2005) § § § l The number of trips is totally 96. One of the whole is the electrical problem. These days, electrical fault is increased. Trip Causes of Electrical Faults in NPPs (1978~2005) § § Until now, the causes of electrical failure are gradual failure and insulation failure, transmission line failure, loose connection, overcurrent, relay failure, and disconnection. There is a close connection among the causes. NICIEL SEMINAR 4 / 19

Electrical Fault by Cases l KAIST NUCLEAR & QAUNTUM Gradual failure and Insulation Failure(40) NICIEL SEMINAR 5 / 19

Electrical Fault by Cases KAIST NUCLEAR & QAUNTUM • Transmission Line failure(33) NICIEL SEMINAR 6 / 19

Electrical Fault by Cases KAIST NUCLEAR & QAUNTUM • Loose Connection(21) NICIEL SEMINAR 7 / 19

Electrical Fault by Cases KAIST NUCLEAR & QAUNTUM • Overcurrent(18) NICIEL SEMINAR 8 / 19

Electrical Fault by Cases KAIST NUCLEAR & QAUNTUM • Relay failure(11) NICIEL SEMINAR 9 / 19

Electrical Fault by Cases KAIST NUCLEAR & QAUNTUM • Disconnection(9) NICIEL SEMINAR 10 / 19

Electrical Preventive Maintenance KAIST NUCLEAR & QAUNTUM Ultrasound Leak Detection NICIEL SEMINAR 11 / 19

Electrical Preventive Maintenance KAIST NUCLEAR & QAUNTUM Infrared Thermography With Thermography, the excessive heat can be readily noted and the temperature rise measured by the infrared system. The increased temperature indicates a potential trouble spot and possible future failure of the component. Infrared inspection is carried out while the electrical system is under load, and requires no physical contact with the system, making it an excellent preventive maintenance tool, causing no disruption to the normal operative routine of a facility. NICIEL SEMINAR 12 / 19

Electrical Preventive Maintenance KAIST NUCLEAR & QAUNTUM Transformer Oil Testing • Dissolved Gas Analysis A gas sample is extracted from the oil and nine key gas components namely: Hydrogen, Oxygen, Nitrogen, Methane, Carbon Monoxide, Carbon Dioxide, Ethane, Ethylene, and Acetylene are analyzed. When a transformer is failing, the chemical compounds in the oil break down to give off these gases. Elevated concentrations can signal corona discharge, overheating, arcing, or cellulose insulation pyrolysis. By using the Transformer Oil Analysis, the fault condition of the transformer can be known. NICIEL SEMINAR 13 / 19

Electrical Preventive Maintenance KAIST NUCLEAR & QAUNTUM Insulation Resistance • The purpose of an insulation resistance (IR) reading is to evaluate the condition of the insulation between conductors and ground. • This is done by applying a direct voltage between the conductors (windings) and the casing of the electric motor (machine) and measuring current leakage across the insulation system. • The readings are applied to Ohm's law (R=V ÷I), which provides a resistance. NICIEL SEMINAR 14 / 19

Summary KAIST NUCLEAR & QAUNTUM • Electricity can be helpful and also dangerous, if not respected. • Electrical failures are caused by gradual failure and insulation failure, transmission line failure, loose connection, overcurrent, relay failure, and disconnection. • Electrical accidents appear to be caused by a combination of some possible factors. • Electrical failures by causes were illustrated as the examples. • The existing ways of electrical preventive maintenance were explained. NICIEL SEMINAR 15 / 19

Further Study KAIST NUCLEAR & QAUNTUM • I want to study insulated materials changing colors according to temperature in order to display heated parts easily. • Also, I will study spray type materials for terminals. • I will study to easily find out the grounding point using new technology. NICIEL SEMINAR 16 / 19

Reference KAIST NUCLEAR & QAUNTUM • Korea Institute of Nuclear Safety : www. kins. re. kr • Ken Leonard and Madding Robert P. ; ”Inspecting Electrical Vaults Using Infrared Thermography”; Proc. Infra. Mation; 2003 • “ A Review of Polarization Index and IEEE Std. 43 -2000” , by Howard w. Penrose, Ph. D. , BJM Corp. NICIEL SEMINAR 17 / 19

2003 North East Blackout: OOPS!! KAIST NUCLEAR & QAUNTUM NICIEL SEMINAR 18 / 19

Major Power Outages Around the World KAIST NUCLEAR & QAUNTUM NICIEL SEMINAR 19 / 19