Урок 7. Unit 7.

1. Прочитайте и запомните следующие слова.

protective relaying – реле защиты, релейная защита;

fault tripping – отключение повреждения;

a bus – (электрическая) шина;

an auxiliary relay – промежуточное реле;

a plunger type – тип реле со втяжным сердечником;

a hinged armature type – электромагнитное реле с подвижным якорем;

a lock-out device – реле блокировки, запирающее (стопорное) реле;

a magnetic flux – магнитный поток;

a unit – элемент, компонент, прибор, устройство, агрегат, аппарат, установка,

блок, узел, модуль, секция, энергоблок, единица;

a back-up relay – реле резервной защиты;

a phase to ground fault – однофазное КЗ;

a phase to phase fault – меж(ду)фазное КЗ;

a ground relay – реле защиты от замыкания на землю;

a torque compensator – насыщающий трансформатор тока;

a saturating transformer – насыщающий трансформатор тока;

a disc – диск, пластина;

a time-overcurrent induction disc relay – индукционное реле времени

максимального тока;

a torque – крутящий момент, вращающий момент;

a lever – рычаг, рукоятка;

a differential relay – дифференциальное реле;

a trip setting – уставка на отключение;

a condenser – конденсатор;

a reactor – (электрический) реактор, катушка индуктивности, дроссель,

элемент с реактивным сопротивлением;

a percentage differential type – дифференциальное реле с заданным

относительным параметром срабатывания,

процентно-дифференциальное реле;

an overcurrent type – реле максимального тока;

a harmonic restraint type – реле с торможением токами высших гармоник;

a voltage type – реле напряжения;

emergency response – меры, предпринимаемые для ликвидации аварии,

восстановления работы;

a movement – движение, передвижение, перемещение, шаг, ход, такт,

действие, манипуляция, управление;

a hinged armature – шарнирный, шарнирно закрепленный якорь;

a relay target – указатель (срабатывания) реле;

a moving – движение, перемещение, передача;

to dampen – демпфировать, успокаивать, тормозить, смягчать, уменьшать,

гасить;

2. Прочитайте текст 7 «Protective Relays». Найдите в тексте примеры

определений, выраженных причастиями.

5. PROTECTIVE RELAYS

A specific knowledge of protective relaying is necessary to operate an electrical system effectively when emergency response is required subsequent to fault tripping. Protective relays provide protection against undesired line, bus or equipment conditions. Control relays provide control or regulating functions. Auxiliary relays provide more contacts, varied functions and/or greater capacity than do protective relays. An auxiliary relay is one which is controlled by another relay.

The three basic types of electro-mechanical relay movements are the plunger type, the hinged armature type and the induction type. The auxiliary relays are usually of the hinged armature type. Many protective relays are of the induction type. Auxiliary relays have more contacts and/or higher contacts current carrying capability than the “primary” relays which cause them to operate. Actually the “86” device functions as an auxiliary relay in order to trip circuit breakers.

Some utilities use the “86” hand reset tripping lock-out devices. Never attempt to hold the reset handle to reset if the device will not “latch” to reset. Doing so could quickly burn up the trip coil if the trip circuit remains energized to the “86”. Instantaneous relays are those that have no inherent time delay. They may be “plunger” or “hinged armature” types. These relays operate by the “solenoid principle”. That means the hinged armature is pulled into a “trip” position by the sufficient magnitude of magnetic flux. If the current is great enough, the flux causes the armature to pull into place, tripping. The instantaneous units in most AC overcurrent relays are of this type.

Primary protective relays provide protection for equipment or circuits. “Back-up” relays normally operate only if primary protective relays have failed. A “back-up” relay action should call immediate attention to this fact.

“Phase” relays are those that protect a given phase. A phase relay provides protection against phase to phase faults. A phase relay may also provide protection against a phase to ground fault but normally will not operate as fast a “ground” relay for that type of fault. A “ground” relay protects any of the three phases from phase to ground faults.

The operation of the AC induction disc element is the basis upon which many electro-mechanical relays function. Alternating current is supplied to the lower pole and subsequently linked to the upper pole by means of a torque compensator. The term “torque compensator” here only means a “saturating transformer”. The upper pole induces current in the disc. Now the current in the disc reacts with the flux produced by the lower pole. The current setting is adjusted by means of changing the distance through which the moving must rotate in order to close.

This description serves to explain the basic operation of a time-overcurrent induction disc relay. This AC overcurrent relay is the type utilized in systems. The numerical designation for this type of relay is device “51”.

The above explanation covered how rotation of the disc could be achieved; however, there is more to be said about an overcurrent relay. Torque is maintained on the disc in the open direction by means of a spring. This spring also serves as a moving conductor like the moving contact with the circuit thereon. Trip time is adjusted by means of a time lever. The time lever determines how much the distance the moving contact must travel through in order to reach the stationary contact. The maximum travel would be through slightly less than 180 degrees. “Minimum trip” is a term which refers to the minimum number of amps which can be passed through the circuit of the relay and still provide enough torque to overcome the spring restraint and slowly rotate the disc and moving contact to the closed (trip) state. “Inverse time characteristic” is a term which refers to the fact that the more amps that pass through the overcurrent relay, the less time it will take to close the contacts. “The more the amps, the less the time to trip.” This electro-mechanical device can only develop so much torque in the closed (trip) direction once it reaches the saturation point. Therefore, regardless of how many amps are passed through, it never becomes an instantaneous device. A permanent magnet acts to dampen disc movement.

Relay target (flag) refers to the visual indicator (when provided) on a relay which is energized when relay contacts close and is unlatched by the magnetic field (solenoid principle) increased by current flow through the trip circuit. The target is only an indication that the relay has operated and otherwise is not affecting the operation of equipment. Just because the target is reset does not indicate the fault is gone. If that circuit were re-energized, the problem may occur again. Conversely, if the targets were not reset, and the problem still existed, it could trip out again and you would not know why it trip the second time. For this reason, always check and record all targets, making certain they are reset prior to energizing the equipment. Time targets are usually operated by DC (trip) current, while many instantaneous targets are dropped by AC secondary current flow.

The overcurrent relay (51) can operate very fast on great quantities of current compared to the minimum tripping amps, but since it never becomes instantaneous, another trip coil is sometimes added to the current of an overcurrent relay. It is an “IT” coil (instantaneous trip) and is set for many times the minimum trips amps of the time overcurrent element.

3. Найдите в тексте английские эквиваленты следующим русским

сочетаниям:

являясь результатом отключения поврежденного участка (повреждения);

обеспечивают больше контактов в отличие от реле защиты;

которые приводят их в действие;

для того, чтобы отключить выключатели цепи;

быстрое выполнение этого могло бы;

это означает, что;

регулируется посредством (за счет) изменения;

относится к тому факту, что;

чем больше ток, тем меньшее время нужно для отключения;

одно только восстановление индикатора в начальное положение не указывает

на то, что;

4. Выберите соответствующий перевод причастий.

undesired замкнутый, включенный

varied включенный, подключенный

given нежелательный

produced увеличенный, усиленный

utilized различный, разнообразный

closed данный

energized повторно включенный

increased используемый применяемый

re-energized произведенный

5. Переведите текст на русский язык.

6. Выберите из текста информацию и расскажите о принципе работы и

назначении релейной защиты.