Focused Practice

I. Answer the following questions:

1. What is an ionizing potential wave (IPW)?

2. What do the ionizing potential waves arise from?

3. What class of IPW is discussed in this paper?

4. What have recent developments in diagnostic techniques allowed?

5. Why have analytical investigations been restricted to one spatial dimension?

6. What do numerical simulations and experiments show?

II. Analyse the grammar structures underlined in the above text.

III. Speak on: The structure and dynamics of streamers.

Unit 37 Grammar: The Present Progressive Tense Word List:

1. series reactor	сглаживающий дроссель
2. power transformer	трансформатор питания
3. fault current limiter	ограничитель аварийного тока
4. device impedance	полное входное сопротивление устройства
5. the superconducting to resistive state transition	переход из сверхпроводящего состояния в резистивное состояние
6. the low inductance air core reactor	воздушный (без железного сердечника) дроссель, имеющий низкую индуктивность
7. the composite reaction textured material	материал, полученный в результате сложной реакции
8. air core	воздушный сердечник
9. HTSC high-temperature superconductivity	высокотемпературная сверхпроводимость
10. system efficiency	эффективность использования системы
11. system performance	показатели работы системы
12. triggering	пуск, запуск, инициирование

High Temperature Superconducting Current Limiting Series Reactor

Modern Power Generators and Electric Utilities are facing a changing environment characterized with continual demand for increasing loads and emphasis on better utilization of existing assets. Increasing environmental concerns present powerful opposition to building large centralized generation plants and new transmission lines.

In order to utilize existing assets better, we are witnessing very intensive development efforts in the area of the plant or system performance monitoring, life management and new FACTS (Flexible AC Transmission System) technology. Both technologies are already offering very effective algorithms, techniques and concepts to work the existing equipment harder. These technologies have limitations in terms of being based on conventional conducting, magnetic and insulation materials.

Further radical improvement of the already optimized equipment and system efficiency can only be based on new materials.

A new design concept of Superconducting Current Limiting Series Reactor has been developed utilizing the characteristics of the composite reaction textured Bi-2212 HTSC material. The current limiting effect has been achieved by the almost instantaneous increase in the device impedance due to the superconducting to resistive state transition of the HTSC material, triggered by combined effect of magnetic field and fault current in excess of the critical levels for selected material. The concept is hybrid (inductive/resistive) with the SC elements placed inside the low inductance air cored reactor which is used to generate an external triggering magnetic field. The device was designed to provide a magnetic field in a way to assist uniform quenching of SC material and minimize electromagnetic forces on SC elements.

Experience gained during this development work is generally applicable for other power engineering equipment, in particular SC POWER transformers which may inherently incorporate the fault current limiting function.

The present practice for limiting fault currents, based on conventional technology, is costly and reduces the reliability and flexibility of power system operation.

At this point, superconductors offer an attractive potential as the basis for a SCCL SR, due to their intrinsic characteristics of transition from superconducting to resistive states.