Call us! To understand what is meant by explosion proof, we must look at the context of the term and the organization that defined it. These definitions set the criteria that must be met by all components installed in hazardous classified locations. To meet the criteria for the explosion proof rating, an enclosure must be able to contain any explosion originating within its housing and prevent sparks from within its housing from igniting vapors, gases, dust, or fibers in the air surrounding it. Therefore, explosion proof, when referring to electrical enclosures, does not mean that it is able to withstand an exterior explosion. Instead, it is the enclosures ability to prevent an internal spark or explosion from causing a much larger blast.
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Explosion Proof Electric Motor
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Register now while it's still free! Already a member? Close this window and log in. Are you an Engineering professional? Join Eng-Tips Forums! Join Us! By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click Here. Related Projects. We have a very few explosion proof motors at our plant. I'm not very experienced in the requirements related to these motors. I am aware the motor receives a certification from UL and that motor repair shops can also receive some sort of certification to work on UL motors.
I once was told that if the motor is opened up by an uncertified shop the UL explosion proof sticker must be removed. The definitive answer will come from your insurance company.
It really doesn't much matter what others say. Bill "Why not the best? I thought the leads or any electrical connection near a motor was potted with explosion proof material which anyone can install or clean out during the install?
Hi ePete, Under European rules - which probably aren't too dissimilar - any work which disturbs a flamepath must be undertaken by a 'competent person'. Removing an endshield would definitely fall into that category. In UK law 'competent person' has a specific meaning and there are accredited training courses which must be passed in order to gain the 'competent' status. It is possible for plant personnel to achieve competent status through, for example, AEMT certification, but unless it is a big facility with a lot of motors the economics don't work.
In-house overhaul of motors doesn't generally work out at all in the UK, it is almost always contracted out these days. Thanks for the replies. I have had opportunity to talk to our insurance rep about a variety of subjects. I don't think this fine level of detail is something they would be involved with or knowledgeable about. For the UL motors I have seen, the conduit is sealed where it enters the terminal box and the terminal box cover has a machined tight fit for sealing repair shop identified deviations in that machined fit requiring repair.
Regardless of what is strictly "required" if that is even defined , one could argue that it's prudent to use a certified shop to make sure something isn't missed that would compromise the original explosionproof design. Hi ePete, The primary purpose of that precisely machined fit isn't for sealing although that is certainly achieved - the main purpose is to help the casing contain the products of an internal explosion and cool them as they pass through that tight flamepath so by the time they are able to leak out of the casing they have cooled to the point where they are not an ignition risk.
Apologies if you already knew this - it wasn't apparent from the post above. Quote electricalPete I have had opportunity to talk to our insurance rep about a variety of subjects. Re-prints of the article were floating around into the late s because while dated, the information remained very useful and relevant.
I never did either until I had to take one apart one day. So it seems there is clear consensus that personnel replacing bearings require some kind of certification specific to UL motors. Now, what about removing the terminal box cover to access connections for testing …. Can this be done without the UL certification? And if so, how is this any different than removing endbells to change bearings?
A lot of this comes down to a mentality of: If there's an explosion, there will undoubtedly be an investigation. If the investigation reveals compromising work's been done there will be hell to pay and pay and pay. If the work that's been done was competent then there is no issue what-so-ever who does it. If while your people replace the bearings they scratch the flanges, leave out bolts, break sealing systems or certification seals, or alter the 'original approved design' and there is an 'event' then you will be found panddleless in a brown smelly river.
No hazardous facility can be 'legislated' into safety, it ultimately comes down to the quality and trust you have in your maintenance staff and safety engineering staff in keeping things safe in a hazardous environment. Where I'm going in this is changing the bearings in an exp motor is not rocket science and is a normal maintenance task that does not need to shopped out to some fancy outside facility any more than one needs to hire specialists to take the cover off of any other exp enclosure in a facility.
It's less of an issue than installing an exp enclosure with the correct feedthroughs, conduiting and the other tasks included. Extra care shall be taken to ensure that joints and flame paths are not damaged during the repair work. I think the manu guide below might give you some idea on the questions your asking depending on how your motors are connected.
When i was doing explosion proof assembly machines, i did not think that someone had to be qualified worker as it related to connections. As long as you followed manufacturers recommendations on the connection method. We deal with Ex gear for underground mines, and basically every piece of electrical equipment that carries an Ex rating can only be worked on by technicians with proper qualifications.
If your motors are Ex, there should be protection methods around the terminal enclosure as well either that is another Ex d enclosure, mentioning flame paths, or they're low voltage intrinsically safe connections, something like that - not sure.
If that terminal box is Ex d and has flamepath gaps between the lid and enclosure, you should have trained guys working on them. If there is potential for someone to incorrectly connect something incorrectly terminated, left a gland out, didn't torque cover bolts to the correct torque, etc , I would want someone trained to work on it.
If you don't know what you're looking for, it's easy to miss something. Electric Pete should receive all the stars given out so far in this thread. Initially, I was going to fire back an answer that YES, the maintenance personnel can open up the connection box. An electrician may understand and competently disconnect, and reconnect the motor. The thread gets tangled more. Another reader is contributing, or tying in the Bureau of Mine Safety into the topic.
We might as well have the auto industry, ships, and railroad people chime in here as well. Now what? Call EASA up and ask them about what varnish to use in rewinding your motor.
They will tell you to refer your question to the varnish manufacturer. Have a great holiday weekend everyone! I think its stating what I mean by complying with manufacturer's recommended installation instructions. Usually what happens is a distributor of the explosion proof product will demo how its implemented, to me this is what is explained below. Its kind of funny how we get wrapped up in who qualifies what in what circumstances.
To me its that simply and lets not get wrapped up in the sematics. Qualified person. One who has received training in and has demonstrated skills and knowledge in the construction and operation of electric equipment and installations and the hazards involved.
Note 1 to the definition of "qualified person:" Whether an employee is considered to be a "qualified person" will depend upon various circumstances in the workplace. For example, it is possible and, in fact, likely for an individual to be considered "qualified" with regard to certain equipment in the workplace, but "unqualified" as to other equipment.
See Note 2 to the definition of "qualified person:" An employee who is undergoing on-the-job training and who, in the course of such training, has demonstrated an ability to perform duties safely at his or her level of training and who is under the direct supervision of a qualified person is considered to be a qualified person for the performance of those duties.
Over here in the UK we have the COMPEX scheme which is a nationally-recognised qualification for those who install and inspect hazardous area equipment.
The COMPEX course covers the various types of hazardous area protection and upon completion of the course the trainee should have enough knowledge to recognise any damage with the potential to compromise safety such as a scratched flamepath. In this context 'install and inspect' would not extend to stripping and rebuilding the motor itself but would certainly cover opening up the temrinal chamber and connecting it up.
Quote: In this context 'install and inspect' would not extend to stripping and rebuilding the motor itself but would certainly cover opening up the temrinal chamber and connecting it up. The makers pick a surface that is predictable in creating a cooling flame path and big enough to limit the explosive over-pressure in the product so it doesn't crack open or grenade.
Typically that's the cover. On all regular enclosures it's just the cover. I suspect it's the terminal box cover on motors because while a motor is large in volume the rotor takes up almost every bit of that volume so the fuel volume is actually quite small.
It's likely the cover. The end-bell is part of the motor structure that has to resist and support the shaft rigidly so I doubt it is also doing flame path cooling. One more reason changing the bearings is not a big issue.
Hi Pete; I sympathize with your problem. In the jurisdiction that I work in, only a licensed electrician may remove the cover of an explosion proof enclosure. A licensed electrician may connect or disconnect the motor. Depending on the local trade jurisdictions an electrician or a millwright may remove and replace the motor.
Bearing replacement will be done in a qualified shop. What is the answer in your jurisdiction? The proper procedure is a matter of liability as determined by the level of risk that your firm is willing to accept and the ruling of the AHJ and of your insurance carrier.
Hi ePete, It has the appearance of a flamepath, with a spigot and a broad flat face to slow and cool the explosion by-products.
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ATEX electric motors
It constitutes as a company the oldest one in its objective in the Greek area, playing always a leading role, since when was founded, till nowadays on the specific branch of the Greek and Balkan market. During the first years of the enterprise operation, is included in its activities, the manufacturing and repairs of direct current motors. Later on, is extending its manufacturing activity and to alternating current generators. After the Second World War and the establishment of alternating current, starts the manufacturing of induction motors, slip ring and squirrel cage ones after special order. The main structure of the Company is consisted, of the main manufacturing section for standard and special asynchronous motors, the section for the repair and maintenance of any type and kind of motors, the test and quality control section, and the research and development section as well. The manufacturing program of our factory includes also except the 3phase squirrel cage motors, slip ring motors also, single phase motors, motors with brake, double speed motors, Ex motors, hollow shaft motors, reduction gear motors, and high and low pressure pumping units.
Staff Writer Jun 26, The majority of these mishaps can be traced to malfunctioning equipment. Electric motors, for instance, involve moving parts that generate heat and can cause arcing or sparking when overworked, posing serious fire hazards. Explosion-proof motors and hazardous location motors are specifically designed to eliminate these risks. But not all explosion-proof electric motors can handle flammable matter in the same capacity. And simply because a motor operates in a hazardous location, the motor is not necessarily explosion-proof. This quick guide breaks down what qualifies as an explosion-proof motor, outlines the various classifications for hazardous locations, and provides a simple five-step approach for choosing the best motor to meet specific application needs. The surface temperature of the electric motor increases due to heating that occurs to match the ignition temperature of the flammable matter that has accumulated in the factory or the industrial structure, causing a spontaneous explosion.
Explosion proof type electric induction motor in line with the movement of standards going global. Catalog Download. Contact Us. We also offer an air cooled heat exchanger, water cooled heat exchanger and the self cooling type model.
Хейла нигде не было. Тогда он вернулся в кабинет и прикрыл за собой дверь, затем заблокировал ее стулом, подошел к столу и достал что-то из выдвижного ящика.
- Это невозможно. Он перезагрузил монитор, надеясь, что все дело в каком-то мелком сбое. Но, ожив, монитор вновь показал то же. Чатрукьяну вдруг стало холодно. У сотрудников лаборатории систем безопасности была единственная обязанность - поддерживать ТРАНСТЕКСТ в чистоте, следить, чтобы в него не проникли вирусы. Он знал, что пятнадцатичасовой прогон может означать только одно: зараженный файл попал в компьютер и выводит из строя программу.
Все, чему его учили, свидетельствовало о чрезвычайности ситуации. Тот факт, что в лаборатории систем безопасности никого нет, а монитор был выключен, больше не имело значения. Главное теперь - сам ТРАНСТЕКСТ. Чатрукьян немедленно вывел на дисплей список файлов, загружавшихся в машину в последние сорок восемь часов, и начал его просматривать.
Когда санитары отвезли тело Танкадо в морг, офицер попытался расспросить канадца о том, что произошло. Единственное, что он понял из его сбивчивого рассказа, - это что перед смертью Танкадо отдал кольцо. - Танкадо отдал кольцо? - скептически отозвалась Сьюзан. - Да. Такое впечатление, что он его буквально всучил - канадцу показалось, будто бы он просил, чтобы кольцо взяли. Похоже, этот канадец рассмотрел его довольно внимательно.
- Стратмор остановился и повернулся к Сьюзан.
Explosion Proof Motors
Ты считаешь, что кто-нибудь готов. Это же крайне недальновидно. Ты говоришь, что наше дерьмовое правительство исходит из высших интересов людей. Но что будет, если какое-нибудь будущее правительство станет вести себя. Ведь эта технология - на вечные времена. Сьюзан слушала его безучастно, от воя сирены у нее закладывало уши.
Хейл же все время старался высвободиться и смотрел ей прямо в .
Understanding Explosion-Proof Motor Classifications
Беккер понял, что с каждой минутой дело все больше запутывается. - С подружкой. Немец был не .
- Червь преодолел уже половину пути. - Забудьте про пленку, - сказал Бринкерхофф. - Вводите ключ и кончайте со всем .
Но Танкадо… - размышляла. - С какой стати такой параноик, как Танкадо, доверился столь ненадежному типу, как Хейл. Сьюзан понимала, что теперь это не имеет никакого значения.
Нужно немедленно доложить обо всем Стратмору.
- Что еще мне остается? - Он представил Хейла на скамье подсудимых, вываливающего все, что ему известно о Цифровой крепости.
- Весь мой план рухнет. Должен быть какой-то другой выход. - Решайте! - крикнул Хейл и потащил Сьюзан к лестнице.