Base Technology Subjects
Electric Power Engineering Research Laboratory
Brief Overview
The Electric Power Engineering Research Laboratory is engaged in the advancement of fundamental
technologies, including electrical insulation, lightning protection, fault current control and high power testing
technologies for power transmission and distribution equipment. It is also developing next generation power
equipment and new electric power technologies.

Achievements by Research Theme
High-voltage & Insulation【Objectives】
To make diagnostic technology for electric power equipment sophisticated, we address clariﬁcation ofdeterioration mechanism for various insulation and sealing materials, making external insulating technology oftransmission line advanced and improvement of accuracy of high-voltage measurement.
【Principal Results】
・We clariﬁed partial discharge properties (relation between quantity of discharge and phase angle) of delamination defects on a simulated insulating layer of electric cable junction. These properties are useful for on-site
diagnostics using small size resonance type power supply.
・The overall uncertainty of peak voltage measurement for several hundred kV lightning impulse voltage wasevaluated to be 0.3 % for the measuring system with a voltage divider, constructing as the Japanese national standard. This means the accuracy of the measuring system is the same as European national standards [H09001].
Lightning and Electromagnetic Environment【Objectives】
Developing the logical technologies for lightning protection measures and insulation coordination in theelectric power systems of ICT society is an object in this ﬁeld. In addition, this ﬁeld aims at establishing the EMC
technology in the power supply facilities and consumer facilities.
【Principal Results】
・The phenomena of lightning strikes on wind mills has become clear through observations of lightning strokes
and measurement of the peak value and electric charge of lightning currents. Furthermore, the statistical characteristics of the lightning phenomena have also become clear [H09005].
・A new calculation method using the numerical electromagnetic ﬁeld analysis was developed for analyzing
induced lightning voltages on distribution lines. The method has clearly explained the inﬂuence of the groundresistance, ground wires and lightning arresters on the induced lightning voltage [H09002].
・In light of the new guidelines issued by ICNIRP, a calculation method of the electric ﬁelds and current thatwere induced inside a human body exposed to the magnetic ﬁeld was developed. In addition, the issues to besolved for applying the calculation method were also examined [H09013].
Applied High Energy Physics【Objectives】
We will develop simulation techniques of pressure rise in electric equipment caused by fault-arc to complement high power short-circuit tests. In addition, we will also develop innovative measurement technologies
using laser or high energy particles and work on its application to diagnosis of power delivery apparatus.
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Electric Power Engineering Research Laboratory【Principal Results】
・We developed a simulation method to predict internal pressure-rise caused by short-circuit fault-arcs, whichlead to damage of electric power apparatus [H09021]. We also developed a numerical model for evaluationof pressure rise and propagation characteristics caused by arc discharge in the protective pipe of CVT cable[H09018].
・High-energy electrons ranging from 16 to 17 MeV, which is sufﬁcient level to produce positrons, were successfully generated by irradiation of ultra-short laser pulses on a gas jet target [H09012].
Electric Power Application【Objectives】
To promote electriﬁcation of transportation sector, etc., we will develop application technologies of powerelectronics related to dc power distribution and electric energy applications, an electromagnetic transient analysis
program for power system and super conductive electrical power equipment.
【Principal Results】
・ A transient analysis program for power systems shown in Fig. 1 has been put in practical use. A new steadystate initialization algorithm taking harmonics and imbalance conditions into account has been developed[H09007].
・ A prototype of bidirectional and wireless charging system for future electric vehicles was developed. Dual
directional charge and discharge were demonstrated successfully [H09015].
・ A prototype of the 2-axis Electromagnetic Stirring System with AC Superconducting Magnets was developed.
It can be applied for stirring high viscous molten metal. Strong and stable stirring was demonstrated [H09016].
High Current Technology【Objectives】
To estimate performance of electric equipment at a short-circuit fault, we improve short-circuit test techniques and establish measuring techniques for power frequency currents.
【Principal Results】
・ In cooperation with STL (Short-Circuit Testing Liaison) comparison tests of high current shunts in high powerlaboratories in Asia with an STL reference shunt were carried out and the test results showed the shunts tested
had a good performance for high current measurements.

Fig. 1 Screenshots of the transient analysis program
Schematic editor (left), line constants calculation routine (upper right) and viewer of waveforms (lower right)

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