Maternal Effects of Japanese Shorthorn Cows on the Growth of Embryo-transferred Japanese Black Calves in a Cow-calf Grazing System

The growth performance of embryo-transferred Japanese Black calves that were born from, and suckled by, Japanese Shorthorn cows in a cow-calf grazing system (BS-group, n = 5) was compared to that of Japanese Black calves from Japanese Black cows in a cowshed (BB-group, n = 5). The daily weight gain from birth to 1 month was higher in the BS-group than in the BB-group (p0.05) was observed between the groups. These results suggest that the maternal effect of Japanese Shorthorn cows was positive for embryo-transferred Japanese Black calf growth during the early suckling stage. As Japanese Black calves are traded at a high price on the Japanese market, we conclude that this proposed production system is likely to improve the profitability of herd management in upland Japan

X-ray Irradiation Induced Discharge of Spherical Void in Epoxy Resin

It is crucial for proper insulation design of cast resin transformer to consider voids and delamination which might exist in cast molding process and/or under long-term operation because of several surface boundaries between resin and conductor. Should such defects in the insulation system exist, it would lead to reduction of the life of the apparatus. In this report, we investigate the relation between the void size and apparent charge of partial discharge (PD) occurring in a model simulating the insulation system of cast resin transformer. It is also important to determine necessary PD detection sensitivity of PD test in a factory as well as in a field. In addition, we investigate X-ray irradiation induced discharge of spherical void in epoxy resin. Physical consideration of the effect of X-ray irradiation on void discharges in epoxy resin was also made. Time lag of void discharges in epoxy resin was also made with attenuation of X-ray irradiation dose considered.2011 Electrical Insulation Conference (EIC), 5-8 June 2011, Annapolis, M

AC Partial Discharge Characteristics and Accumulation Charge after Lightning Impulse in Cast Resin Transformer

Cast resin transformer (voltage transformer: VT) composed of solid insulation might cause insulation performance degradation by defects such as void existing in the insulation system. In a factory, AC PD test is usually conducted after applying a number of applications of standard lightning impulse voltage to practical VT. Lightning impulse voltage test is made in the power equipment to guarantee surge insulation performance. However, it is reported that withstand lightning impulse voltage test may give influence on AC partial discharge characteristics, especially partial discharge inception voltage (PDIV). This effect is considered to arise from the charge accumulated in the void by the impulse voltage pre-stress. This paper deals with the influence of lightning impulse application on subsequent AC partial discharge characteristics with accumulated charge by the pre-stress considered. An attempt is made to measure impulse partial discharge, and estimate the accumulated charge. Investigation is also made on the impulse pre-stress effect on the subsequent AC PD characteristics for a model specimen simulating insulation system of a cast resin transformer. An attempt is also made to estimate the accumulated surface charge density after the impulse voltage application. Moreover, we measure impulse PD current and then estimate the charge of impulse PD so as to examine the correlation between the impulse PD charge and the accumulated charge estimated from the reduction of the first AC PDIV.20th International Symposium on High Voltage Engineering, August 28 - September 01, 2017, Buenos Aires, Argentin