Не запускается электродвигатель гудит: Электродвигатель гудит, но не крутится – Электропривод

Неисправности асинхронных электродвигателей | Электрик

Конденсаторный двигатель не стартует – Электропривод

10 часов назад, Вадим666 сказал:

А двигатель ,точно конденсаторный.

 

Двигатель такой. Вал 14мм, общий вес 6.1 кг. Работал с конденсатором 4 мкф. Совершенно точно был снят со старой стиралки. Краска на шильдике облезла, и видно только выбитую цифру “70”, возможно, год выпуска.

До того, как я его разобрал, он работал. Разбирал с целью замены подшипников, (они проржавели за 20 лет простоя) и переделки его на левое вращение. Для этого я планировал поставить якорь валом в хвост. Собственно, все это я и сделал, после чего мотор перестал запускаться. Можно крутануть рукой, и он будет нормально вращаться в направлении первоначальной закрутки. Можно подключить любую обмотку к сети по отдельности. Все тоже самое, только гул и вибрации сильнее.

2 часа назад, самодельщик сказал:

как вы соединяете обмотки? рабочая должна подключатся сразу в сеть. пусковая через конденсатор. один провод должен быть общим

Так и сделал. Обмотку с малым сопротивлением в сеть, с высоким сопротивлением – в сеть через конденсатор. Схема как бы стандартная.

 

2 часа назад, самодельщик сказал:

как вы описываете запуск  получается вы конденсатор подключили последовательно с обоими обмотками.

Не знаю, где вы это прочли.

 

10 часов назад, 546 сказал:

Вал крутится легко,не клинит?

Не клинит. Новые подшипники -2RS. Они, конечно, немного туже раскатанных, но с гораздо более тугими ржавыми, что стояли до, мотор прекрасно запускался.

Изменено 05.07.2019 19:02 пользователем telegraphist

Неисправности электродвигателей – ООО ПФ “КРЭДО”

Чтобы быстро определить, почему электродвигатель вышел из строя и в каких узлах произошел сбой – рекомендуется ознакомиться с перечнем наиболее популярных неисправностей. Ниже приведены характерные поломки, причины возникновения и способы их правильного устранения.

 

Неисправность: Электродвигатель сильно гудит при запуске, не набирает оборотов, или не запускается совсем.

Причина: Обрыв цепи статора, обрыв цепи одной из фаз (наконечник, кабель, контактор), перегорела защитная вставка.
Решение: Восстановить цепь питания, проверить и сменить предохранитель.

Причина: Обрыв обмотки статора.
Решение: Перемотать статор.

Причина: Обрыв в цепи фазного ротора (кабель, реостат, щетки).
Решение: Восстановить цепь ротора.

Причина: Нарушение контакта между стержнями и кольцами в короткозамкнутом роторе (дым и искры).
Решение: Ремонт ротора.

Причина: Заклинивание вала ЭД или привода.
Решение: Произвести очистку двигателя или его механизма от возможных загрязнений.

Причина: Низкий пусковой момент, который не позволяет ротору набрать обороты.
Решение: Замена на аналогичный двигатель с большим пусковым моментом.

Причина: Соединение звездой вместо треугольника
Решение: Проверить правильность схемы соединения, произвести переподключение.

 

Неисправность: Сильный нагрев в подшипниках скольжения.

Причина: Отсутствие или недостаточное количество смазки.
Решение: Произвести смазку подшипников должным образом.

Причина: В масле имеются примеси и механические частицы.
Решение: Произвести замену смазки.

Причина: Износ деталей полумуфт, дефект кольца, бой шейки вала и т.п.
Решение: Ремонт механической части двигателя.

 

Неисправность: Сильный нагрев в подшипниках качения.

Причина: Отсутствие или недостаточное поступление смазки, избыток смазки.
Решение: Произвести смазку подшипников должным образом, проследить за возможными утечками, убрать излишки смазки.

Причина: Дефекты подшипника, выраженные посторонним шумом.
Решение: Замена подшипника.

 

Неисправность: Корпус электродвигателя сильно нагревается при работе.

Причина: Слабая работа принудительной системы охлаждения.
Решение: Очистка каналов и технологических отверстий.

Причина: Забиты вентиляционные каналы для пропускания холодного воздуха.
Решение: Продувка сжатым воздухом.

Причина: Повышенная нагрузка по току.
Решение: Понизить нагрузку или заменить на ЭД большей мощности.

 

Неисправность: Искрение при работе ЭД и появление дыма.

Причина: Ротор соприкасается с поверхностью статора.
Решение: Ремонт двигателя.

Причина: Некорректная работа в защитной или пускорегулирующей системе.
Решение: Диагностика защитной или пускорегулирующей системы и устранение дефектов.

 

Неисправность: Повышенные вибрации при работе ЭД.

Причина: Износ соединительных муфт
Решение: Отсоединить муфты и проверить ЭД без подключения к механизму.

Причина: Нарушена центровка двигателя и механизма.
Решение: Проверить и затянуть крепежные детали, а также крепления к станине.

Причина: Износ подшипников, разбалансировка ротора, взаимное смещение положения ротора и статора.
Решение: Ремонт ЭД.

 

Неисправность: Колебания потребления тока статора ЭД в процессе его работы.

Причина: Плохое соединение в цепи – для фазного ротора, для короткозамкнутого ротора – плохое соединение между стержнями и кольцами.
Решение: Ремонт ЭД (при больших колебаниях – незамедлительно, при небольших скачках – чем раньше – тем лучше).

 

Неисправность: Искры из коллекторно-щеточного узла. Сильный нагрев и обгорание соответствующей арматуры.

Причина: Щетки плохо отшлифованы.
Решение: Отшлифовать щетки.

Причина: Недостаточный зазор для свободного движения щеток в щеткодержателях.
Решение: Выставить допустимый зазор в пределах 0.2-0.3 мм.

Причина: Загрязнение контактных колец или щеток.
Решение: Произвести очистку, устранить источник распространения загрязнения.

Причина: На контактных кольцах имеются борозды и неровности.
Решение: Проточить и произвести шлифовку колец.

Причина: Слабый прижим щеток.
Решение: Отрегулировать усилие нажатия.

Причина: Отсутствует равномерное распределение тока между щетками.
Решение: Отрегулировать усилие нажатие щеток и их свободный ход в щеткодержателях, проверить состояние контактной группы Траверс, оценить состояние токопроводов.

 

Неисправность: Активная сталь статора перегревается равномерно по всей поверхности.

Причина: Повышенное напряжение питания.
Решение: Организовать дополнительное охлаждение электродвигателя и понизить напряжение электросети до штатного уровня.

 

Неисправность: Сильный нагрев активной стали статора в отдельном месте на холостом ходу при штатном напряжении в сети.

Причина: Местное КЗ между отдельными листами активной стали.
Решение: Очистить и прошлифовать место соприкосновения листов, покрыть их диэлектрическим лаком.

Причина: Нарушена изоляция в местах стяжки активной стали.
Решение: Восстановить изоляцию на данных участках.

 

Неисправность: ЭД с фазным ротором при загрузке не выходит на номинальные обороты.

Причина: Некачественное соединение в пайке контактного кольца ротора.
Решение: Произвести контроль надежности пайки визуально и «проверкой с падением напряжения».

Причина: Слабый контакт обмотки ротора с контактным кольцом.
Решение: Проверить и восстановить токопроводящие соединения.

Причина: Слабое соединение в щеточном узле и механизме КЗ ротора.
Решение: Произвести шлифовку и регулировку усилия прижатия щеток.

Причина: Слабое соединение контактных проводов в пусковой аппаратуре.
Решение: Восстановить целостность и надежность контактов на соответствующем участке.

 

Неисправность: Двигатель с фазным ротором запускается при незамкнутой цепи ротора, а под нагрузкой не может выйти на номинальный режим.

Причина: КЗ в обмотке якоря, соединительных хомутах лобовых соединений.
Решение: Изолировать соприкасающиеся хомуты, Устранить КЗ и произвести замену поврежденной обмотки якоря.

Причина: КЗ обмотки ротора по двум участкам одновременно.
Решение: Устранить КЗ и произвести замену обмотки неисправной катушки.

 

Неисправность: Двигатель с короткозамкнутым ротором не набирает штатное количество оборотов.

Причина: Отработало тепловое реле, вышли из строя предохранители или автомат.
Решение: Проверка и устранение данных неисправностей.

 

Неисправность: При запуске электродвигателя электрическая дуга перекрывает контактные кольца.

Причина: В щеточном узле или на контактных кольцах присутствует пыль, грязь.
Решение: Провести чистку.

Причина: Высокая влажность в месте эксплуатации ЭД.
Решение: Нанести дополнительный слой диэлектрика или произвести замену ЭД на другой, пригодный для эксплуатации в текущих условиях.

Причина: Обрыв в контактных соединениях реостата или ротора.
Решение: Провести диагностику всех соединений, устранить неисправности.

Неисправности асинхронных электродвигателей

Неисправность	Причина	Способ устранения
Двигатель не запускается, не вращается и не издает шума.	1. Не включается магнитный пускатель.	Проверить напряжение на питающих проводах, включая выход магнитного пускателя.
	2. К двигателю не подходят все три или подходят только две фазы питающего напряжения.	Проверить, нет ли обрыва в в обмотке статора. При обнаружении неисправности заменить статор или двигатель целиком.
	3. Вышла из строя обмотка статора.	Заменить статор
Двигатель не отключается	Не отключается магнитный пускатель или другой пусковой аппарат	Измерить напряжение на питающих проводах, включая выход магнитного пускателя
Двигатель не вращается и ненормально гудит	1. Подходят только две фазы питающего напряжения	Проверить напряжение на питающих проводах, включая выход магнитного пускателя
	2. Обгорел зажим в коробке двигателя	Разобрать, почистить и снова собрать зажим или сделать отдельное соединение, которое необходимо заизолировать
Двигатель не вращается	Вышел из строя подшипник	Заменить подшипник
Двигатель работает неустойчиво	Магнитный пускатель включается неустойчиво и искрит	Устранить неисправность в цепи катушки магнитного пускателя или в его магнитной системе
Двигатель запускается и останавливается	Слабое нажатие контактов магнитного пускателя	Устранить неисправность в цепи катушки магнитного пускателя или в его магнитной системе
Двигатель не развивает нормальных оборотов и нагревается	1. Двигатель работает с перегрузкой	Устранить перегрузку двигателя
	2. Вышел из строя подшипник	Заменить подшипник
Двигатель гудит и не развивает номинального момента	Витковое замыкание одной фазы в обмотке статора, межфазное замыкание в обмотках статора	Найти место повреждения обмотки и устранить замыкание, в случае необходимости, перемотать поврежденную часть обмотки
Равномерный перегрев всего электродвигателя	Неисправен вентилятор	Снять защитный кожух и отремонтировать вентилятор
Сильный нагрев подшипников	1. Неправильно установлены подшипники	Отремонтировать с устранением неполадок
	2. Плохое состояние масла	Долить или заменить масло
	3. Подшипники износились	Заменить подшипники
Выход из строя двигателя, полное или частичное обугливание изоляции обмотки	Большой, выше номинального ток в обмотке двигателя появляется из-за длительной перегрузки механизма, его заклинивания, при несимметрии напряжения в питающих проводах, при аварийных режимах	Заменить двигатель

Виды неисправности электродвигателя

01.04.2015

Электродвигатель нагревается, гудит, стучит или вовсе не включается. Вот наиболее распространенные виды неисправностей электродвигателей. Причины таких поломок могут быть самые разные.

Асинхронный двигатель не включается

Одна из причин — закороченные положения пускового реостата или контактных колец. Если причина первая, то необходимо привести пусковой реостат в нужное положение. Если проблема в кольцах, то нужно поднять приспособление, поддерживающее их. Также нарушить работу электродвигателя может короткое замыкание в цепи статора. Обнаружить его можно на ощупь по повышенному нагреву обмотки. Не забудьте, предварительно отключить электродвигатель от сети. Если предположение подтвердилось и обмотка нагрелась, то ремонт и т.о электродвигателя неизбежно.

Асинхронный двигатель не трогается с места

Обрыв фаз питания (одной или двух) может стать причиной такой неисправности. Распознать его удастся при помощи внешнего осмотра, либо выполнив измерения мегомметром. Если обрыв случится во время работы электродвигателя, он не остановится, но начнет гудеть сильнее обычного.

Асинхронный двигатель гудит во время работы

Помимо обрыва одной фазы, другой причиной излишнего шума может стать перегрузка электродвигателя. Чтобы в этом убедиться, достаточно разобщить его с приводным механизмом и запустить вхолостую.

Нагревается подшипник

У такой неисправности несколько причин. Это может быть недостаточная величина зазора между шейкой вала и вкладышем подшипника, слишком мало или слишком много масла в подшипнике, а также загрязнение или применение масла несоответствующих марок.

Электродвигатель искрит и дымит во время работы

Скорее всего причина кроется в задевании ротора за статор. Также искры под щетками могут появиться из-за неправильно подобранных щеток, их слабого нажатия на коллектор, его недостаточно гладкая поверхность или неправильное расположение щеток. Чтобы устранить такие неполадки достаточно расположить щетки на нейтральной линии.

При перемотке электродвигателей, ремонте сварочного оборудования и устранении неполадок обращайтесь за помощью к профессионалам. Они в кратчайшие сроки приведут любой электродвигатель в рабочее состояние!

Другие события 90000 Starting Motor With Auto-transformer 90001 90002 90002 Starting Motor With Auto-transformer 90004 Circuit and function 90005 90006 An auto-transformer starter makes it possible to start squirrel-cage induction motors with reduced starting current, as the voltage across the motor is reduced during starting. 90007 90006 In contrast to the star-delta connection, only three motor leads and terminals are required. On starting, the motor is connected to the tappings of the auto-transformer; transformer contactor K2M and star contactor K1M are closed.90007 90006 90011 90012 The motor starts at the voltage reduced by the transformer, with a correspondingly smaller current. 90013 90014 90007 90006 By this means the feeding current in comparison to direct starting would be 90011 90012 reduced by the square of the transformer voltage ratio 90013 90014; nevertheless, it is in most cases noticeably higher, as it also covers the 90011 90012 relatively high transformer losses 90013 90014. 90007 90006 Depending on the tapping and starting current ratio of the motor, the 90011 90012 starting current 90013 90014 lies at 90011 90012 (1 … 5) · Ie 90013 90014.In contrast, the motor torque falls with the square of the voltage across the windings. Auto-transformers usually have three available taps in each phase (90011 90012 for example 80%, 65%, 50% 90013 90014), so that the motor starting characteristic can be adjusted to the load conditions. 90007 90006 If the motor has reached 90011 90012 80 … 95% of its rated speed 90013 90014 (90011 depending on the desired reduction of the current surge after switching-over 90014), the 90011 90012 star contactor K1M 90013 90014 on the transformer is opened.90007 90006 Now the transformer part-windings act as chokes. The motor voltage is only reduced by the chokes below the supply voltage and the motor speed does not fall. The 90011 90012 main contactor K3M 90013 90014 closes via auxiliary contacts of the star contactor and applies the full supply voltage to the motor. 90007 90006 For its part, the main contactor K3M drops out the 90011 90012 transformer contactor K2M 90013 90014. 90007 90006 90011 90012 The entire procedure is thus uninterrupted.90013 90014 90007 90070 90070 Figure 1 – Auto-transformer starter with uninterrupted switching over (Korndörfer starting method) 90072 90072 90074 Rating of the starter 90075 90006 90011 90012 The main contactor K3M and the motor protective device F1 are selected according to the motor rated operational current I 90079 e 90080. 90013 90014 Transformer contactor and star contactor are only briefly closed during starting. 90007 90006 Their rating is determined by the 90011 90012 required contact breaking capacity 90013 90014, as they must reliably cope with any unforeseen disconnection during start up.90007 90006 The star contactor also operates with every start-up during switching-over. The values ​​of the rated operational currents for the transformer contactor K2M, depending on the start time and starting current, are between 90011 90012 (0.3 … 1) · I 90079 e 90080 90013 90014, for the star contactor between 90011 90012 (0.45 … 0.55 ) · I 90079 e 90080 90013 90014. 90007 90072 90074 Testing AC Motors and Working on Westinghouse Generator 90075 90006 90108 90109 90007 90006 90011 90012 Resource: 90013 Allen Bradley – Low Voltage Switchgear and Controlgear 90014 90007 .90000 Brushed DC motor 90001 90002 By Dmitry Levkin 90003 90004 Brushed DC electric motor 90005 is a rotating DC electric machine that converts DC electric power into mechanical energy, in which at least one of the windings involved in the main process of energy conversion is connected to a commutator. 90002 Figure 1 – Permanent magnet DC motor in the section 90003 90002 90004 Rotor 90005 is rotating part of the electric machine.90003 90002 90004 Stator 90005 is a fixed part of the motor. 90003 90002 90004 Inductor 90005 (excitation system) is part of the DC commutator machine or synchronous machine, creating magnetic flux for the formation of the torque. The inductor includes either 90004 permanent magnets 90005 or a 90004 field winding 90005. The inductor can be part of both the rotor and the stator. In the motor shown in fig. 1, the excitation system consists of two permanent magnets and is part of the stator.90003 90002 90004 Armature 90005 is a part of a DC commutator machine or a synchronous machine in which an electromotive force is induced and a load current flows [2]. As the armature can act as a rotor and stator. In the motor shown in fig. 1, the rotor is an armature. 90003 90002 90004 Brushes 90005 is a part of the electrical circuit through which the electric current is transmitted from the power source to the armature. Brushes are made from graphite or other materials. The DC motor contains one pair of brushes or more.One of the two brushes is connected to the positive and the other to the negative terminal of the power supply. 90003 90002 90004 Commutator 90005 is a part of the motor in contact with the brushes. With the help of brushes and a commutator, the electric current is distributed across the coils of the armature winding [1]. 90003 90002 According to the stator construction, the brushed motor can be with permanent magnets and with wound stator. 90003 90038 Permanent magnet DC motor 90039 90002 Permanent magnet DC motor scheme 90003 90002 Permanent magnet DC motor (PMDC motor) is the most common among the brushed DC motor.The inductor of this motor includes permanent magnets that create a magnetic field of the stator. Permanent magnet DC motors are usually used in tasks that do not require high power. PMDC motors are cheaper in production than wound field DC motors. At the same time, the torque of the PMDC motor is limited by the field of permanent magnets of the stator. The PMDC motor reacts very quickly to voltage changes. Thanks to the constant field of the stator, it is easy to control the speed of the motor.The disadvantage of a PM DC motor is that over time the magnets lose their magnetic properties, as a result of which the stator field decreases and the motor performance decreases. 90003 90044 90004 Advantage: 90005 90047 best price / quality ratio 90048 90047 high torque at low speed 90048 90047 fast voltage response 90048 90053 90044 90004 Disadvantage: 90005 90047 permanent magnets over time, as well as under the influence of high temperatures lose their magnetic properties 90048 90053 90038 Wound field DC motor 90039 90002 Separately excited DC motor scheme 90003 90002 Shunt wound DC motor scheme 90003 90002 Series wound DC motor scheme 90003 90002 Compound wound DC motor scheme 90003 90070 Separately excited and shunt wound motors 90071 90002 In separately excited electric motors, the field winding is not electrically connected to the armature winding (figure above).Usually, the excitation voltage U 90073 FW 90074 differs from the voltage in the armature circuit U. If the voltages are equal, then the field winding is connected in parallel with the armature winding. The use in the electric drive separately excited or shunt wound motor is determined by the electric drive scheme. Properties (characteristics) of these motors are the same [3]. 90003 90002 In shunt wound brushed DC motors, the currents of the field winding (inductor) and the armature are independent of each other, and the total motor current is equal to the sum of the field winding current and the armature current.During normal operation, 90004 increasing the supply voltage 90005 increases the total current of the motor, which leads to an increase in the stator and rotor fields. With an increase in the total motor current, the speed also increases, and the torque decreases. 90004 When the motor load increased 90005, the armature current increases, with the result that the armature field increases. As the armature current increases, the inductor (field winding) current decreases, resulting in a decrease in the inductor field, which leads to a decrease in motor speed and an increase in torque.90003 90044 90004 Advantage: 90005 90047 almost constant torque at low speed 90048 90047 good adjusting properties 90048 90047 no loss of magnetism over time (since there are no permanent magnets) 90048 90053 90044 90004 Disadvantage: 90005 90047 more expensive than PMDC motor 90048 90047 the motor goes out of control if the inductor current drops to zero 90048 90053 90002 Shunt-wound DC motor has the torque / speed characteristic with decreasing torque at high speeds and high, but more constant torque at low speeds.The current in the inductor winding and the armature does not depend on each other, thus, the total current of the electric motor is equal to the sum of the currents of the inductor and the armature. As a result, this type of motor has excellent speed control characteristics. Shunt-wound brushed DC motor is commonly used in applications that require a power of more than 3 kW, in particular in automotive applications and industry. In comparison with PMDC motor, the shunt wound DC motor does not lose its magnetic properties with time and is more reliable.The disadvantages of the shunt wound brushed DC motor is higher cost and the possibility of the motor runaway if the inductor current decreases to zero, which in turn can lead to motor failure [5]. 90003 90070 Series wound DC motor 90071 90002 In series wound brushed DC motors, the field winding is connected in series with the armature winding, and the excitation current is equal to the armature current (I 90073 e 90074 = I 90073 a 90074), which gives the motors special properties. Under small loads, when the armature current is less than the rated current (I 90073 a 90074 & lt I 90073 rat 90074) and the magnetic system of the motor is not saturated (Ф ~ I 90073 а 90074), the electromagnetic torque is proportional to the square of the current in the armature winding: 90003 90002, 90003 90044 90047 where 90120 M 90121 is the motor torque, N ∙ m, 90048 90047 90120 з 90073 М 90074 90121 is a constant coefficient determined by the design parameters of the motor ,, 90048 90047 Ф is main magnetic flux, Wb, 90048 90047 90120 I 90073 a 90 074 90121 is armature current, A.90048 90053 90002 With load increasing, the magnetic system of the motor is saturated and the proportionality between the current I 90073 a 90074 and the magnetic flux Ф is disturbed. With significant saturation, the magnetic flux Ф with increasing I 90073 a 90074 practically does not increase. The graph of the dependence M = f (I 90073 a 90074) in the initial part (when the magnetic system is not saturated) has the shape of a parabola, then, when saturated, deviates from the parabola and in the region of large loads turns into a straight line [3].90003 90002 Performance characteristic of series wound DC motor 90003 90002 Electromechanical characteristic of series wound DC motor 90003 90002 90004 Important: 90005 It is unacceptable to include a series wound brushed DC motor in the power grid at idle (no load on the shaft) or with a load of less than 25% of the rated, as at low loads the armature speed increases dramatically, reaching values ​​at which mechanical damage to the motor is possible, therefore in drives with series wound DC motors, it is unacceptable to use a belt drive, if it is broken, the motor goes to idling mode.An exception is made for series wound DC motors with a power of up to 100-200 W, which can operate in idle mode since their mechanical and magnetic losses at high speeds are commensurate with the rated motor power. 90003 90002 The ability of series wound DC motors to develop a large electromagnetic torque provides them with good starting properties. 90003 90044 90004 Advantage: 90005 90047 high torque at low speed 90048 90047 no loss of magnetism over time 90048 90053 90044 90004 Disadvantage: 90005 90047 low torque at high speed 90048 90047 more expensive than PMDC motor 90048 90047 poor speed control due to the series connection of the armature and inductor windings 90048 90047 the motor goes out of control if the inductor current drops to zero 90048 90053 90002 Series wound brushed DC motor has a high torque at low speed and develops high speed with no load.This electric motor is ideal for devices that need to develop a high torque (cranes and winches), as the current of the stator and the rotor increases under load. Unlike PMDC motors and shunt wound brushed DC motors, the series wound DC motors does not have the exact characteristics of speed control, and in case of a short circuit of the field winding it can become uncontrollable. 90003 90070 Compound wound DC motor 90071 90002 Compound wound brushed DC motor has two field windings, one of them is connected in parallel with the armature winding, and the second is connected in series.The ratio between the magnetizing forces of the windings can be different, but usually one of the windings creates a large magnetizing force and this winding is called main, the second winding is called auxiliary. If the windings are connected such that the series field aids the shunt field, then the motor is called 90004 Cumulative compound brushed DC motor 90005. On the other hand, if the windings are connected such that the two fields oppose each other, then the motor is called the 90004 Differential compoud brushed DC motor 90005.The speed characteristics of cumulative compound brushed DC motor are located between the speed characteristics of shunt wound and series wound DC motors. Opposite connection of the windings (differential compounding) is used when it is necessary to obtain a constant rotational speed or an increase in the rotational speed with increasing load. Thus, the performance characteristics of a compound wound DC motor is close to those of a shunt or series wound brushed DC motor, depending on which field winding plays the main role [4].90003 90044 90004 Advantage: 90005 90047 good speed control 90048 90047 high torque at low speed 90048 90047 motor runaway less likely 90048 90047 no loss of magnetism over time 90048 90053 90044 90004 Disadvantage: 90005 90047 more expensive than other brushed DC motors 90048 90053 90002 Compound brushed DC motors has the performance characteristics of shunt and series wound brushed DC motors.It has a high torque at low speed, as well as a series wound brushed DC motor and good speed control, like, a shunt wound brushed DC motor. Compound wound brushed DC motor runaway is less likely, because the shunt current should decrease to zero, and the serial field winding should be short-circuited. 90003 90002 The performance properties of brushed DC motors are determined by their operating, electromechanical and mechanical characteristics, as well as their adjustment properties. 90003 90002 Torque-speed curves of brushed DC motors 90003 90038 Torque constant 90039 90002 For a brushed DC motor, the torque constant is determined by the formula: 90003 90002, 90003 90044 90047 where Z is total number of conductors, 90048 90047 Ф is magnetic flux, Wb [1] 90048 90053 90222 Also read 90223 .90000 Single-phase induction motor 90001 90002 By Dmitry Levkin 90003 A 90004 single-phase induction electric motor 90005 is an induction electric motor that operates from a single-phase AC power grid without using a frequency converter and which, in the basic mode of operation (after starting), uses only one winding (phase) of the stator. 90002 90004 Split-phase motor 90005 is a single-phase induction motor having an auxiliary (starting) winding on the stator, offset from the main one, and a squirrel-cage rotor [2].90003 90010 Construction of Single-phase Induction Motor with auxillary or starting winding 90011 The main components of any electric motor are the rotor and the stator. The rotor is the rotating part of the electric motor, the stator is the fixed part of the electric motor, with the help of which a magnetic field is created for the rotation of the rotor. 90002 The main parts of a single-phase induction motor: rotor and stator 90003 90002 The 90015 stator 90005 has two windings located at an angle of 90 ° relative to each other.The main (working) winding usually occupies 2/3 of the slots of the stator core, the other winding is called auxiliary (starting) and usually takes 1/3 of the slots of the stator. 90003 90002 The motor is actually two-phase, but since only one winding is working after starting, the electric motor is called single-phase. 90003 90002 The 90021 rotor 90005 usually represents itself a short-circuited winding, also called “squirrel cage” due to the similarity. Whose copper or aluminum rods are closed with rings at the ends, and the space between the rods is often filled with an aluminum alloy.The rotor of a single-phase motor can also be made in the form of a hollow nonmagnetic or hollow ferromagnetic cylinder. 90003 90002 Single-phase induction motor with auxiliary winding has two windings located perpendicularly relative to each other 90003 90010 Working principle of single-phase induction motor 90011 90002 To better understand the working of a single-phase induction motor, let’s consider it with only one turn in the main and auxiliary windings. 90003 90002 Analysis of the case with two windings having one turn 90003 90002 Consider the case when no current flows in the auxiliary winding.When the main stator winding is turned on, the alternating current, passing through the winding, creates a pulsating magnetic field, stationary in space, but varying from + Ф 90033 max 90034 to-Ф 90033 max 90034. 90003 90002 Start 90003 90002 Stop 90003 90002 Fluctuating magnetic field 90003 90002 If you place a squirrel-cage rotor having an initial rotation in a fluctuating magnetic field, it will continue to rotate in the same direction.90003 90002 To understand the working principle of a single-phase induction motor, we separate the fluctuating magnetic field into two identical rotating fields having an amplitude equal to Ф 90033 max 90034/2 and rotating in opposite directions with the same frequency: 90003 90002, 90003 90052 90053 where n 90033 90055 f 90056 90034 is the rotational speed of the magnetic field in the forward direction, rpm, 90058 90053 n 90033 90055 r 90056 90034 is the rotational speed of the magnetic field in the opposite direction, rpm, 90058 90053 f 90033 1 90034 is stator current frequency, Hz, 90058 90053 p is a number of poles pairs, 90058 90053 n 90033 1 90034 is the rotational speed of magnetic flux, rpm 90058 90075 90002 Start 90003 90002 Stop 90003 90002 The decomposition of the fluctuating magnetic flux into two rotating 90003 90082 The action of the fluctuating field on a rotating rotor 90083 90002 Consider the case when the rotor in a fluctuating magnetic flux has an initial rotation.For example, we manually spun the shaft of a single-phase motor, one winding of which is connected to an AC power grid. In this case, under certain conditions, the motor will continue to develop torque, since the rotor 90004 slip 90005 relative to the forward and reverse magnetic flux will be unequal. 90003 90002 Assume that the forward magnetic flux Ф 90033 f 90034, rotates in the direction of rotor rotation, and the reverse magnetic flux Ф 90033 r 90034 in the opposite direction. Since, the rotational speed of the rotor n 90033 2 90034 is less than the rotational speed of the magnetic flux n 90033 1 90034, the slip of the rotor relative to the flux Ф 90033 f 90034 will be: 90003 90002, 90003 90052 90053 where s 90033 90055 f 90056 90034 is rotor slip relative to the forward magnetic flux, 90058 90053 n 90033 2 90034 is rotor speed, rpm, 90058 90053 s is induction motor slip 90058 90075 90002 Forward and reverse rotating magnetic flux instead of fluctuating magnetic flux 90003 90002 The magnetic flux Ф 90033 r 90034 rotates counter to the rotor rotation, the rotor rotation speed n 90033 2 90034 relative to this flux is negative, and the slip of the rotor relative to Ф 90033 r 90034 90003 90002, 90003 90052 90053 where s 90033 90055 r 90056 90034 is rotor slip relative to reverse magnetic flux 90058 90075 90002 Start 90003 90002 Stop 90003 90002 Rotating magnetic field penetrating the rotor 90003 90002 Current induced in the rotor by an alternating magnetic field 90003 90002 According to the law of electromagnetic induction, the forward Ф 90033 f 90034 and reverse Ф 90033 r 90034 magnetic fluxes generated by the stator winding induce EMF in the rotor winding, which, respectively, in the short-circuited rotor generate currents I 90033 2f 90034 and I 90033 2r 90034.The frequency of the current in the rotor is proportional to the slip, therefore: 90003 90002, 90003 90052 90053 where f 90033 2f 90034 is frequency of the current I 90033 2f 90034 induced by the forward magnetic flux, Hz 90058 90075 90002, 90003 90052 90053 where f 90033 2r 90034 is frequency of the current I 90033 2r 90034 induced by the reverse magnetic flux, Hz 90058 90075 90002 Thus, when the rotor rotates, the electric current I 90033 2r 90034 induced by the reverse magnetic field in the rotor winding has a frequency f 90033 2r 90034 much higher than the frequency f 90033 2f 90034 of the rotor current I 90033 2f 90034 induced by the forward field.90003 90004 Example: 90005 for a single-phase induction motor working from the mains with a frequency f 90033 1 90034 = 50 Hz at n 90033 1 90034 = 1500 and n 90033 2 90034 = 1440 rpm, 90002 slip of the rotor relative to the forward magnetic flux s 90033 f 90034 = 0.04; 90195 the frequency of the current induced by the forward magnetic flux f 90033 2f 90034 = 2 Hz; 90195 slip of the rotor relative to the reverse magnetic flux а s 90033 r 90034 = 1,96; 90195 the frequency of the current induced by the reverse magnetic flux f 90033 2r 90034 = 98 Hz 90003 90002 According to Ampere’s law, a torque occurs as a result of the interaction of the electric current I 90033 2f 90034 with the magnetic field F 90033 f 90034 90003 90002, 90003 90052 90053 where M 90033 90055 f 90056 90034 is the magnetic torque created by the forward magnetic flux, N ∙ m, 90058 90053 з 90033 90055 M 90056 90034 is constant coefficient determined by the motor construction 90058 90075 90002 The electric current I 90033 2r 90034, interacting with the magnetic field Ф 90033 r 90034, creates a braking torque M 90033 r 90034 directed against the rotation of the rotor, that is, opposite to the torque M 90033 f 90034: 90003 90002, 90003 90052 90053 where M 90033 r 90034 is magnetic torque created by reverse magnetic flux, N ∙ m 90058 90075 90002 The resulting torque acting on the rotor of a single-phase induction motor, 90003 90002, 90003 90002 90004 Note: 90005 Due to the fact that in a rotating rotor forward and reverse magnetic field will induce a current of different frequency, the torques acting on the rotor in different directions will not be equal.Therefore, the rotor will continue to rotate in a fluctuating magnetic field in the direction in which it had an initial rotation. 90003 90082 The braking effect of the reverse field 90083 90002 When a single-phase motor is operating within the rated load, that is, at small slip values ​​s = s 90033 f 90034, the torque is generated mainly due to the torque M 90033 f 90034. The braking effect of the torque of the reverse field M 90033 r 90034 slightly. This is due to the fact that the frequency f 90033 2r 90034 is much higher than the frequency f 90033 2f 90034, therefore, the inductive reactance of the rotor winding а х 90033 2r 90034 = x 90033 2 90034 s 90033 r 90034 to the current I 90033 2r 90034 is much more than its active resistance.Therefore, the current I 90033 2r 90034 having a large inductive component has a strong demagnetizing effect on the reverse magnetic flux Ф 90033 r 90034, significantly weakening it. 90003 90002, 90003 90052 90053 where r 90033 2 90034 is rotor rods resistance, Ohm, 90058 90053 x 90033 2r 90034 is reactive impedance of rotor rods, Ohm. 90058 90075 90002 If we consider that the power factor is small, then it will become clear why the M 90033 r 90034 under the load of the motor does not have a significant braking effect on the rotor of a single-phase motor.90003 90002 With one phase, the rotor can not be started. 90003 90002 The rotor having the initial rotation will continue to rotate in the field created by the single-phase stator 90003 90082 The action of a fluctuating field on a fixed rotor 90083 90002 With a stationary rotor (n 90033 2 90034 = 0) slip s 90033 f 90034 = s 90033 r 90034 = 1 and M 90033 f 90034 = M 90033 r 90034, therefore the initial starting torque of a single-phase induction motor M 90033 f 90034 = 0.To create the starting torque, it is necessary to bring the rotor in rotation in one direction or another. Then s ≠ 1, the equality of the torques М 90033 f 90034 and М 90033 r 90034 is violated and the resulting electromagnetic torque acquires some value M = M 90033 90055 f 90056 90034 – M 90033 90055 r 90056 90034 ≠ 0. 90003 90010 Starting of a single-phase induction motor. How to create an initial rotation? 90011 90002 One way to create a starting torque in a single-phase induction motor is to position the auxiliary (start) winding B, which is offset in space relative to the main (run) winding A at an angle of 90 electrical degrees.In order that the stator windings to create a rotating magnetic field, the currents I 90033 A 90034 and I 90033 B 90034 in the windings must be out of phase relative to each other. To obtain a phase shift between the currents I 90033 A 90034 and I 90033 B 90034, the auxiliary (start) winding B is connected to a phase-shifting element, which is resistance (resistor), inductance (choke) or capacitance (capacitor) [1]. 90003 90002 After the motor rotor accelerates to a rotational speed close to steady, the starting winding B is disconnected.The auxiliary winding is disconnected either automatically using a centrifugal switch, a time delay relay, a current or a differential relay, or manually using a button. 90003 90002 Thus, during start-up, the single-phase induction motor operates as two-phase, and after the start-up, as single-phase. 90003 90010 Single-phase induction motor connection 90011 90082 Resistance start induction motor 90083 90002 90004 Resistance start 90005 induction motor is a split-phase motor, in which the auxiliary winding circuit is distinguished by increased resistance.90003 90002 Ohmic phase shift, bifilar starting winding 90003 90002 Different resistance and inductance of the windings 90003 90002 To start a single-phase induction motor, you can use a starting resistor, which is connected in series to the starting winding. In this case, it is possible to achieve a phase shift of 30 ° between the currents of the main and auxiliary windings, which is quite enough to start the motor.In a motor with starting resistance, the phase difference is explained by the different complex impedance of the circuits. 90003 90002 Also, a phase shift can be created by using a start winding with a lower inductance and higher resistance. For this, the starting winding is done with a smaller number of turns and using a thinner wire than in the main winding. 90003 90082 Capacitor start induction motor 90083 90002 90004 Capacitor start 90005 induction motor is a split-phase motor, in which the auxiliary winding circuit with a capacitor is switched on only for the duration of the start.90003 90002 Capacitive phase shift with a starting capacitor 90003 90002 To achieve the maximum starting torque, it is required to create a circular rotating magnetic field, this requires that the currents in the main and auxiliary windings are shifted relative to each other by 90 °. The use of a resistor or choke as a phase-shifting element does not allow for the required phase shift. Only the inclusion of a capacitor of a certain capacity allows for a phase shift of 90 °.90003 90002 Among phase shifting elements, only a capacitor allows achieving the best starting properties of a single-phase induction electric motor. 90003 90002 Motors in the circuit of which a permanently switched on capacitor use two phases for operation and are called capacitor ones. The working principle of these motors is based on the use of a rotating magnetic field. 90003 90002 90004 Shaded pole induction motor 90005 is a split-phase motor in which the auxiliary winding is short-circuited.90003 90002 The 90004 stator 90005 of a shaded pole single-phase induction motor usually has salient poles. Each stator pole is divided into two unequal sections by an axial groove. A smaller section of the pole has a short-circuited turn. The 90004 rotor 90005 of a shaded pole single-phase motor is short-circuited in the form of a squirrel cage. 90003 90002 When the single-phase stator winding is turned on to the power grid, a fluctuating magnetic flux is created in the motor magnetic circuit.One part of which passes through unshaded Ф ‘, and the other Ф “along the shaded section of the pole. Flow Ф” induces EMF E 90033 k 90034 in a short-circuited turn, resulting in a current I 90033 k 90034 lagging from E 90033 k 90034 in phase due to the inductance of the coil. The current I 90033 k 90034 creates a magnetic flux Ф 90033 k 90034, directed oppositely to Ф “, creating the resulting flux in the shaded section of the pole Ф 90033 s 90034 = Ф” + Ф 90033 k 90034. Thus, in a motor, the flows of the shaded and unshaded sections of the pole are shifted in time by a certain angle.90003 90002 The spatial and temporal shear angles between the flows Ф 90033 s 90034 and Ф ‘create conditions for a rotating elliptical magnetic field to appear in the motor, since Ф 90033 s 90034 ≠ Ф’. 90003 90002 Starting and working properties of the considered motor are low. Efficiency is much lower than that of capacitor start induction motors of the same power, which is associated with significant electrical losses in a short-circuited coil. 90003 90002 The 90004 stator 90005 of such a single-phase motor is made with salient poles on a non-symmetrical laminated core.The 90004 rotor 90005 has squirrel-cage winding. 90003 90002 This motor for an operation does not require the use of phase-shifting elements. The disadvantage of this motor is low efficiency. 90003 90415 Also read 90416 .90000 The basics of Built-in Motor Protection for Beginners 90001 90002 Why is motor protection necessary? 90003 90004 In order to avoid unexpected breakdowns, costly repairs and subsequent losses due to motor downtime, it is important that the motor is fitted 90005 with some sort of protective device 90006. 90007 90008 90008 The basics of Built-in Motor Protection for Beginners (on photo: View of installed thermostat inside motor; credit: johndearmond.com) 90004 This article will deal with 90005 built-in motor protection 90006 with thermal overload protection to avoid damage and breakdown of motor.The built-in protector always require an external circuit breaker while some built-in motor protection types even require an overload relay. 90007 90014 Internal protection // Built into the motor 90015 90004 Why have built-in motor protection, when the motor is already fitted with overload relays and fuses? Sometimes the overload relay does not register a motor overload. 90007 90004 90005 Here are a couple examples of this // 90006 90007 90022 90023 If the motor is covered and is slowly warmed up to a high damaging temperature.90024 90023 In general, high ambient temperature. 90024 90023 If the external motor protection is set at a too high trip current or is installed in a wrong way. 90024 90023 If a motor, within a short period of time, is restarted several times, the locked rotor current warms up the motor and eventually damages it. 90024 90031 90004 The degree of protection that an internal protection device provides is classified in the IEC 60034-11 standard. 90007 90034 90035 TP designation 90036 90004 TP is the abbreviation for thermal protection.Different types of thermal protection exist and are identified by a 90005 TP-code (TPxxx) 90006 which indicates: 90007 90041 90023 The type of thermal overload for which the thermal protection is designed (1 digit) 90024 90023 The numbers of levels and type of action (2 digit) 90024 90023 The category of the built-in thermal protection (3 digit) 90024 90048 90004 90005 When it comes to pump motors, the most common TP designations are: 90006 90007 90041 90023 90005 TP 111 90006 – Protection against slow overload 90024 90023 90005 TP 211 90006 – protection against both rapid and slow overload.90024 90048 90063 90063 Internal protection built into windings 90004 90005 Indication of the permissible temperature level when the motor is exposed to thermal overload. Category 2 allows higher temperatures than category 1 does. 90006 90007 90069 90070 90071 90072 Symbol 90034 (TP) 90074 90072 Technical overload with variation 90034 (1 digit) 90074 90072 Number of levels and function area (2 digits) 90074 90072 Category 90034 (3 digits) 90074 90083 90071 90072 TP 111 90074 90087 Only slow (i.e. constant overload) 90074 90089 1 level at cutoff 90074 90072 1 90074 90083 90071 90072 TP 112 90074 90072 2 90074 90083 90071 90072 TP 121 90074 90089 2 levels at emergency signal and cutoff 90074 90072 1 90074 90083 90071 90072 TP 122 90074 90072 2 90074 90083 90071 90072 TP 211 90074 90087 Slow and fast (i.e. constant overload and blocked condition) 90074 90089 1 level at cutoff 90074 90072 1 90074 90083 90071 90072 TP 212 90074 90072 2 90074 90083 90071 90072 TP 221 90074 90089 2 levels at emergency signal and cutoff 90074 90072 1 90074 90083 90071 90072 TP 222 90074 90072 2 90074 90083 90071 90072 TP 311 90074 90089 Only fast (i.e. blocked condition) 90074 90089 1 level at cutoff 90074 90072 1 90074 90083 90071 90072 TP 312 90074 90072 2 90074 90083 90160 90161 90004 Information about which type of protection has been applied to a motor can be found on the nameplate using a TP (thermal protection) designation according to 90005 IEC 60034-11 90006. 90007 90004 90005 In general, internal protection can be implemented using two types of protectors: 90006 90007 90022 90023 Thermal protectors or 90024 90023 Thermistors.90024 90031 90034 90035 Thermal protectors – built into the terminal box 90036 90004 Thermal protectors or thermostats use a snapaction, bi-metallic, disc type switch to open or to close the circuit when it reaches a certain temperature. Thermal protectors are also referred to as Klixons, (trade name from Texas Instruments). 90007 90004 When the bi-metal disc reaches a predetermined temperature, 90005 it opens or closes a set of contacts in an energized control circuit 90006. Thermostats are available with contacts for normally open or normally closed operation, but the same device can not be used for both.90007 90004 Thermostats are precalibrated by the manufacturer and can not be adjusted. The discs are hermetically sealed and are placed on the terminal board. 90007 90187 90187 Top nameplate: TP 211 in a MG 3.0 kW motor equipped with PTC; Bottom nameplate: TP 111 in a Grundfos MMG 18.5 kW motor equipped with PTC. 90034 90190 90190 Motor thermal switch symbols 90004 90005 Symbols (left to right): 90006 90007 90022 90023 Thermal switch without heater 90024 90023 Thermal switch with heater 90024 90023 Thermal switch without heater for three-phase motors (star-point protector) 90024 90031 90004 A thermostat can either 90005 energize an alarm circuit 90006, if normally open, or 90005 de-energize the motor contactor 90006, if normally closed and in series with the contactor.90007 90004 Since thermostats are located on the outer surface of the coil ends, they sense the temperature at that location. In connection with three-phase motors, thermostats are considered unstable protection against stall or other rapidly changing temperature conditions. 90007 90004 90005 In single phase motors thermostats do protect against locked-rotor conditions. 90006 90007 90004 Go back to Index ↑ 90007 90034 90035 Thermal switch – built into the windings 90036 90004 Thermal protectors can also be built into the windings, see the illustration below.They operate as a sensitive power cut-out for both single and three-phase motors. In single-phase motors, up to a given 90005 motor size around 1.1 kW 90006 it can be mounted directly in the main circuit to serve as an on-winding protector. 90007 90225 90225 Thermal protection symbol 90004 Thermal protection to be connected in series with the winding or to a control circuit in the motor. 90007 90229 90229 Thermal protection built into the windings 90004 Klixon and Thermik are examples of thermal switch These devices are also called PTO (Protection Thermique à Ouverture).90007 90034 90234 90234 Current and temperature sensitive thermal switches: Top: Klixons; Bottom: Thermik – PTO 90034 90035 Internal fitting 90036 90004 In single-phase motors one single thermal switch is used. In three-phase motors 2 thermal switches connected in series are placed between the phases of the motor. In that way all three phases are in contact with a thermal switch. 90007 90004 Thermal switches can be retrofitted on the coil end, but the result is an increased reaction time.The switches have to be connected to an external monitoring system. In that way the motor is protected against a slow overload. The thermal switches do not require an amplifier relay. 90007 90004 Thermal switches CAN NOT protect against locked- rotor conditions. 90007 90004 Go back to Index ↑ 90007 90034 90014 How does a thermal switch function? 90015 90004 The curve on your right-hand side shows the resistance as a function of the temperature for a typical thermal switch. Depending on the thermal switch manufacturer, the curve changes.90007 90004 90005 TN is typically around 150 – 160 ° C. 90006 90007 90256 90256 Resistance as a function of the temperature for a typical thermal switch 90004 Go back to Index ↑ 90007 90034 90035 Connection 90036 90004 Connection of a three-phase motor with built-in thermal switch and overload relay. 90007 90034 90035 TP designation for the diagram 90036 90004 Protection according to the IEC 60034-11 standard: 90005 TP 111 (slow overload) 90006. In order to handle a locked-rotor, the motor has to be fitted with an overload relay.90007 90272 90272 Automatic reclosing (left) and manual reclosing (right) 90004 Where: 90007 90041 90023 90005 S1 90006 – On / off switch 90024 90023 90005 S2 90006 – Off switch 90024 90023 90005 K 90006 1 – Contactor 90024 90023 90005 t 90006 – Thermal switch in motor 90024 90023 90005 M 90006 – Motor 90024 90023 90005 MV 90006 – Overload relay 90024 90048 90004 90005 Thermal switches can be loaded as followed: 90006 90007 90004 U 90307 max 90308 = 250 V AC 90034 I 90307 N 90308 = 1.5 A 90007 90004 90005 I 90307 max 90308 90006 = 5.0 A (cut-in and cut-out current) 90007 90004 Go back to Index ↑ 90007 90034 90035 Thermistors – also built into the windings 90036 90004 The second type of internal protection is the thermistors or 90005 Positive Temperature Coefficient sensors (PTC) 90006. The thermistors are built into the motor windings and protect the motor against locked-rotor conditions, continuous overload and high ambient temperature. 90007 90004 Thermal protection is then achieved by monitoring the temperature of the motor windings with PTC sensors.If the windings exceed the rated trip temperature, the sensor undergoes a rapid change in resistance relative to the change in temperature. 90007 90004 As a result of this change, the internal relays de-energize the control coil of the external line break contactor. As the motor cools and an acceptable motor winding temperature has been restored, the sensor resistance decreases to the reset level. 90007 90004 At this point, the module resets itself automatically, unless it was set up for manual reset.When the thermistors are retrofitted on the coil ends, the thermistors can only be classified as 90005 TP 111 90006. The reason is that the thermistors do not have complete contact with the coil ends, and therefore, it can not react as quickly as it would if they were fitted into the winding originally. 90007 90336 90336 Thermistor / PTC 90004 The thermistor temperature sensing system consists of 90005 positive temperature coefficient sensors (PTC) embedded in series of three 90006 – one between each phase – and a matched solid-state electronic switch in an enclosed control module.A set of sensors consists of three sensors, one per phase. 90007 90342 90342 PTC protection built into windings 90004 90345 Only temperature sensitive. The thermistor has to be connected to a control circuit, which can convert the resistance signal, which again has to disconnect the motor. Used in three-phase motors. 90346 90007 90004 The resistance in the sensor remains relatively low and constant over a wide temperature band and increases abruptly at a pre-determined temperature or trip point.90007 90004 When this occurs, the sensor acts as a 90005 solid-state thermal switch 90006 and 90005 de-energizes a pilot relay 90006. 90007 90004 The relay opens the machine’s control circuit to shut down the protected equipment. When the winding temperature returns to a safe value, the module permits manual reset. 90007 90004 Go back to Index ↑ 90007 90004 90345 90005 Reference // 90006 Grundfos – Motor Book (Download here) 90346 90007 .