Development of a Compact Measurement System of Transport Characteristics in HTS Conductors by Using an HTS Current
In order to realize HTS power machines and devices with high performance, it is important to evaluate the characteristics of HTS conductors quantitatively. We developed a compact system to measure the transport characteristics of HTS conductors under various experimental conditions. This system enables us to measure the transport characteristics of straight HTS conductors up to a current capacity of 1 kA class at 77 K, 66 K, and 4.2 K. The measurement of transport current losses is done by the Poynting vector method. The distribution of Poynting vectors around the sample conductor can be obtained by using many sets of both potential leads and pickup coils. An HTS current transformer (HTS-CT) is used to feed current to the sample conductor for the measurement. A secondary current of about 1 kA at 77 K can be induced when the primary current is 40 A. The sample conductor is connected to the secondary coil of this transformer. As a sample conductor, we used a conductor consisting of 16 parallel Ag-sheathed Bi-2223 multifilamentary tapes. The joint method between the HTS-CT and sample conductors is also examined. Based on these results, the usefulness of this measurement system is discussed.
Measurement of Transport Current Losses in HTS Conductors With Large Current Capacity by Using HTS Current Transformer
In order to evaluate the transport current loss characteristics in HTS conductors with large current capacity, we developed a new compact measurement system. This system enables us to measure the transport current losses electrically in the straight HTS conductors with the current capacity of 1 kA class by using the small capacity AC power supply of about 50 A. In this system, an HTS current transformer is used to feed current to the sample conductor for the measurement. The secondary current of this current transformer can be induced at about 1 kA at 77 K when the primary current is 40 A. The current transformer is made very compactly, and the externals size is 70 mm in diameter, and 110 mm in length. The sample conductor is connected with the secondary coil of this current transformer. The loss measurement is done by the Poynting vector method. The distribution of Poynting vectors around the sample conductor can be obtained by using many sets of both a potential lead and a pickup coil. To confirm the validity of this measurement system, we measured the transport current losses in an HTS conductor. As a sample conductor, we used a parallel conductor composed of 16 Ag-sheathed Bi-2223 multifilamentary tapes. The obtained results showed that this compact system was useful for measuring AC loss characteristics of large scale HTS conductors.
La inseguridad jurídica en normas de contratación estatal
It is established by different studies that the issue of government procurement has been marred by several factors, the test objective to publicize these factors, we take as starting point the constant conflict between the branches of government to try and organize this subject; will collect and analyze diverse regulatory and case material in order to achieve evidence and demonstrate the different concepts of constant change that produces excessive regulation of the subject procurement and is in turn causing rapid changes that result in legal uncertainty for our law on the Contract Status.