Fig, 1. Waveform of the short-circuit current peculiar to a metal. Fig. 2. Waveform of arc short-circuit current. 398 T. IEE Japan, Vol. 113-B, No. 4,

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しおりわたぬき
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1 Development of a Quick-Acting Type Fuses for Protection of Low Voltage Distribution Lines Terukazu Sekiguchi, Member, Masayuki Okazaki, Member, Tsuginori Inaba, Member (CRIEPI), Naoki Ikeda, Member, Toshiyuki Kobayashi, Non-member, Yoshinori Takakuwa, Non-member (Osaka Fuse) A short-circuit fault current in a low voltage distribution line from a branch point to a house is usually reduced with time by increasing resistance of conductors due to temperature rise and also by arc voltage. Bacause of features mentioned above, the operating time of conventional fuses may be remark ably prolonged. In order to eliminate that defect a bypass type of the quick-acting fuse has been developed. The main results are as follows : (1) A bypass type of the quick-acting fuses short-circuits the fault line at the branch point by utilizing the large electro-magnetic force due to the fault current. (2) In order to protect almost low voltage distribution lines the minimum operating current of the fuses is settled to be 1,000 A. (3) The bypassing time of the fault line by the newly developed fuse is only 6 ms and 10 ms in case of a fault current of 2 ka in the metallic contacting faults, and the arc short-circuit faults, respectively, those being about 1/100 in comparison with the operating time of the conventional fuses. (4) The operating time of the new fuses is 140 ms in case of the same fault current in the metallic contacting fault, which is only about 1/4 of that of the conventional fuses.

2 Fig, 1. Waveform of the short-circuit current peculiar to a metal. Fig. 2. Waveform of arc short-circuit current. 398 T. IEE Japan, Vol. 113-B, No. 4, '93

3 Fig. 3. Example of distribution lines. Fig. 4. Basis constitution of device. Fig. 5 Example of the operating time calculation result of bypass device.

4 Fig. 6. Short-circuit current calculation result on V -connection transformer. 400 T. IEE Japan, Vol. 113-B, No. 4, '93

5 Fig. 8. Test circuit. Fig. 7. Structure of bypass fuse.

6 Fig. 10. Compared actuation of wide use Fig. 9. Compared actuation of wide use fuse and bypass fuse in metal short-circuit fault. fuse and bypass fuse in arc short-circuit fault. 402 T. IEE Japan, Vol. 113-B, No. 4,193

7 Fig. 11. Bypass fuse.

8 404 T. IEE Japan, Vol. 113-B, No. 4, '93

Fig. 1. Relation between magnetron anode current and anode-cathod voltage. Fig. 2. Inverter circuit for driving a magnetron. 448 T. IEE Japan, Vol. 11

Fig. 1. Relation between magnetron anode current and anode-cathod voltage. Fig. 2. Inverter circuit for driving a magnetron. 448 T. IEE Japan, Vol. 11 High Frequency Inverter for Microwave Oven Norikazu Tokunaga, Member, Yasuo Matsuda, Member, Kunio Isiyama, Non-member (Hitachi, Ltd.), Hisao Amano, Member (Hitachi Engineering, Co., Ltd.). Recently resonant