Transformer Parts and Functions

hi John here in this video we're going to look at the dry type transformer the hermetic type transformer and the conservator type transformer we're going to look at the transformer components such as the core and windings and then we're going to look at some of the other components that you're likely to see such as the bushings gas actuated relay temperature thermometer and the dehydrator breather so let's get stuck right in and we can start by looking at the heart of the transformer which is to transform a core so here we have a 3d model of the transformer core we'll do a little spin as you can see this core has three limbs and these three limbs indicate to us that this is a three-phase transformer the top and the bottom of the transformer core are known as the yoke and these three pieces in the middle are known as the limbs each limb correlates to one phase of the transformer the core itself is clamped together usually using adhesive or some straps if we look on the bottom here you can actually see there are three straps these items here and you'll see there's also straps on the other side one two three so the transformer core is clamped together and the reason it's clamped together is because the core is not one solid block of metal it's actually a series of metal sheets that have been clamped together you'll actually call these laminate steel sheets you can see on the side here that we've got these straight lines these straight lines indicate to us that the sheets are of a different geometry and as you've clamped them together you get this wavy pattern if we can see I'll move over to another limb you can also see over here and that's because the core is not perfectly cylindrical now the reason that we clamped these very thin laminate sheets together is because we want to reduce the hysteresis and the eddy current losses so we'll clamp all of the metal sheets together to form a limb and then we'll plant the metal sheet pieces together to form the yokes as to say the top and the bottom of the transformer call now each of the sheets is insulated from its neighbor and the reason we do this is because we want to completely insulate or isolate each of these metal sheets in order that we reduce the eddy current and hysteresis losses when we have electrical current flowing through the windings and the windings wrap around each one of these limbs then we create an electromagnetic field and the call is going to become magnetized the job of the core is to direct this magnetic field in order that we can get a high magnetic field density or magnetic flux so that's what the core is doing so we've got our limbs 1 2 3 got the yokes at the top and the bottom of the core and the core itself consists of very thin steel laminations that have been clamped together and have been isolated from each other usually by using some form of lacquer or coating and then once it's all together we're going to clamp it together or perhaps glue it together and that is our transformer core the rest of the assembly that we're looking at now is simply to hold the core in position so we've seen a section at the bottom here that is to secure the core in the base of the transformer to make sure it doesn't move around and we can see it top as well we also have his installation to secure it to the top of the tank and again this stops any movement of the core within the transformer casing this type of core could be used for a dry type transformer a hermetic type transformer or a conservator type transformer the design does not change that much the only noticeable change that you will see is if you are using a single phase transformer instead of a three-phase transformer like that currently shown so now we've had to look at the transformer core let's go and have a look at the next item on the list which is going to be the windings so now you can see we're looking at a dry type transformer this is a type of transformer that is not insulated by a liquid and the liquid may be oil or perhaps some sort of synthetic oil or even a biodegradable type of oil but either way it's the dry type transformer also sometimes referred to as a cast resin type transformer we can see it's got wheels on the bottom for moving it into position and we've got these great pieces these are for cooling the transformer if we go up we can see the connections on the back of the transformer but if we break it down into its components you can see there are quite a lot of them there's that core again as we were looking at earlier I'll see if I can actually assemble it slightly we might see the actual shape of the core as it comes together you could see there there are the straps that we were talking about earlier these straps are used to clamp the core together and we should be able to see the top of the core coming down at some point okay the top of the core has now been installed unfortunately didn't get the good chance to have a look at it and there are the low voltage connections coming out of the top but let's explode it into its components again so there's a core and we can see here all of these circular items are going to be installed onto each of Limbs remember one limb is one phase so this is a three-phase transformer and within this group we're going to have low voltage windings and high-voltage windings the low voltage windings are going to be installed closest to the core so they're going to be wrapped around or very close chassé to the core immediately after the low voltage windings we're going to have high-voltage windings so we've got our primary and secondary windings installed and if we push the play button we can actually see them coming down onto the core you come back clamps that comes with some sort of insulator most likely and here comes some windings and the HV windings that go on the outside once that's all assembled it's going to look a lot like this and we can see by looking at the back what type of wiring configuration that transformer has the windings themselves are going to be made of copper or aluminium aluminium is usually used if there is no consideration to space if you have a lot of room you can use an aluminium type transformer generally they'll be bigger than transformers that use copper for the windings this is because the conductivity of copper is higher than aluminium and their ability to carry current is also higher however aluminium is cheaper and if you've got the space then you can install a transformer with aluminium windings but just remember low voltage windings they're going to be wrapped first around the core high-voltage windings are going to be wrapped second around the low-voltage windings themselves and then we're going to assemble the whole thing together the windings themselves are going to be able to copper or aluminium and that is transformer as we have it now the core and the windings are the most essential pieces of the transformer technically you can even manufacture a transformer without the core although it will not be very efficient the Drive type transformer that we're looking at now is the simplest of the three that we're going to look at and this dry toy transformer consists of only the core windings and some cooling fans on the bottom let's now have a look at a hermetic type transformer so here we are we're now looking at a hermetic liquid immersed transformer have a spin we can see on the top that we've got some low voltage bushings that sees four thick ones here the reason they are the low voltage bushings or the reason that you can tell is because the connections are very large the reason they're large is because the voltage is low and the current is high so that's a giveaway that the low voltage bushings are these four here we go on the other side we can see the high voltage bushings and that would be these three here one two three to give away for those is simply the voltage has been increased therefore the current has been reduced so we can see the current carrying pieces of the bushing that's this metal piece here and this one over here those pieces are going to be a lot of thinner because the current they carry is going to be a lot less however the voltage is going to be higher and that is why they have more insulation than the low voltage bushings so if you step up the voltage you're gonna need more insulation and if you step up the current then you're going to need a thicker conductor let's break this down into its individual components again just have a look see what is inside the box we can see there there is our transformer core again three limbs that's three-phase we've got the two yokes on at the bottom one at the top then we have our bushings and all of that can be assembled again to complete the Hermetic type transformer so essentially the hermetic type transformer is a dry type transformer but with a box around it or a casing that is full with a insulating liquid now this insulating liquid is typically mineral oil about 95% the time it's going to be mineral oil and the whole thing sits in a bath of mineral oil the reason it's called hermetic is because it is totally isolated from the atmosphere or from the external environment if you think about it another way just imagine it's a hermit all of the parts within the transformer don't want to come into contact with anything else a bit like a hermit who lives in a cave on a hill so this transformer is classed as hermetic because the internal parts don't want to come into contact with the outside once the transformer is sealed and the casing is sealed he shouldn't be reopened again however there exceptions to this such as when you perform oil analysis etc but this depends upon the manufacturer we've already discussed the pushings let's have a look at a few other items that we can see we've got a filling pipe that would be this area here we've got some lifting bolts or some lifting eyes that's one two and another two on the other side so that's for positioning the transformer or for installing it there's the other two one two and then we've got a temperature indicator zoom in we can see it here and that's going to measure the temperature of the insulating liquid which again might be mineral oil or perhaps it will be silicon or perhaps it will be some sort of synthetic Easter which is more or less a biodegradable oil manufactured from plants we zoom out we can see that the casing itself is not perfectly square it's got these fins attached to the side these fins are used for cooling the transformer what's actually going to happen is that some of the insulating liquid is going to absorb the heat generated by the transformer and it's going to pass that heat on to the fins and the things are going to pass the heat on to the air so the reason for the fins is to increase the contact surface area between the tank and the air and this means we're going to get a much higher heat transfer rate if we can keep the transformer cool then we can also load it more heavily at least up to a point important to realize that if you can keep the transformer cool then you'll also extend its youthful working life overheating is typically one of the big killers of transformers let's now have a look at the conservative type transformer which i think is the most interesting and has a lot more components compared to the dry and hermetic type transformers so here we are we're now looking at a conservator liquid immersed transformer the reason it's called a conservator type transformer is because of the tank on the back which is known as the conservator tank that is this item here we can see the bushings passing through the transformer casing and pointing upwards as you can see on the left side there are four high voltage bushings and three low voltage bushings the high voltage bushings have more insulation and the low voltage bushings have less insulation the purpose of the Bushies is simply to connect the internal windings of the transformer to the outside electrical circuit and we want to do this without raising the electrical potential of the tank itself and that's what the bushings allow us to do they allow us to pass the cable through or to connect the electrical circuit from the inside to the outside without raising the electrical potential of the transformer tank itself let's go over to our can thank again the conservative tech is installed to allow for expansion of the insulating liquid when it gets heated up or when it cools down the Transformers heavily loaded then the insulating liquids gonna heat up and it's going to expand upwards when a transformer cools down the insulating liquid is also going to cool down and then the insulating liquid level is also going to drop so as we heat up the insulating liquid it's going to expand and as we cool it down it's going to contract in order to know what the level is we install a mug and this is a magnetic hole gage we can see here the temperature at 20 degrees we should have this level so if we have 20 degrees now the level will be here as the temperature increases the level will increase this is not a temperature gauge this is a level gauge the 20 degrees Celsius is just for reference what the level should be at that temperature if we look also on the bottom we can see these two red lines or two red triangles these are used as low level and low low level alarm set points it's important that we maintain a good head of insulating liquid within the conservator tank because if that level drops down you could get a catastrophic failure of the transformer and obviously this is not what we want we look inside I can show you the working lever so there is the lever or the float and you can see that as the level would increase the float would be pushed upwards and as the level decreases the float would sink back down again so that's how it works just remember though that this lever and float is not connected directly to the outside gauge it's actually connected magnetically it's coupled magnetically that's why it's called a magnetic oil gauge so we have a form of level measurement here on the side of the conservator but there is also an interesting component fitted below the conservator and this is known as a dehydrating breather sometimes called a silica breather because it uses silica gel as the transformer heats up the liquid is going to expand the insulating liquid is going to expand and we're going to push air out of the conservator tank and it's going to come out through the silica breather just go up and see if I can find the holes where it comes out okay so we can see the holes in the side of the breather and the area is going to be pushed out through these holes because the liquid is expanding in the conservator tank and it's going to be pushed through the silica gel breather and then out of these holes to atmosphere when the liquid cools down because the transformer is perhaps not so heavily loaded we're going to draw air back in through these holes again and then it's going to be drawn into our conservator tank and that is the problem if we're drawing air directly into the conservator tank we want to ensure that it does not contain any moisture if it does we're going to get a problem this may lead to a buildup of sludge when the moisture comes into contact with oxygen not only that but a dielectric strength for our insulating liquid is going to be reduced so these are all negative effects so what we'll do we will pass the air through a silica gel breather that is this item here it's full of silica gel beads and the silica gel beads will remove the moisture from the air as they remove the moisture they're going to change color and when the color has changed by three-quarters we know it's time to change the silica gel beads so the color change is purely for a visual indicator to see how saturated the silica gel beads are once the air has been dried it's going to pass into Conservator tank there is one other interest in aspect of the silica gel breather or the dehydrating breather and that is the oil cup on the bottom and this is used to separate dust particles as the air is drawn in and through the breather so we use this oil or the oil cup to attract bits of dust and as the air bubbles through the oil we're going to separate the dust particles or foreign bodies from the airstream and that's going to ensure that we don't get any dirt or dust going into our conservator tank and mixing with the insulating liquid so the dehydrated breather consists of an oil cup for separating dust particles and other foreign bodies and a silica gel breeder or a dehydrating element which is then used to remove moisture the reason I call it a dehydrates sometimes instead of a silica gel breather is simply because the dehydrating medium may not be silica gel it might be something different so don't always assume it's going to be silica gel it's just if silica gel is used ninety percent of the time let's now have a look at one of the most important pieces of the transformer and this is the gas actuated relay the gas actuated relay is contained within this square box you may also have heard the term book called freely although the book called freely and a gas actuated relay are slightly different a gas actuated relay protects against small electrical faults within the transformer and large electrical faults within the transformer a book called relay protects against small and large electrical faults but also against a low insulating liquid scenario so if we have a small electrical fault within the transformer we're going to heat up insulating liquid and this is then going to generate small bubbles of gas the small bubbles of gas are going to slowly accumulate within the book called relay you're going to push a float downwards and then we are going to set off an alarm which tells the engineers that there is a small electrical fault within the transformer if we have a large electrical fault we're going to get a sudden increase in pressure and a large pocket of gas this pocket of gas is going to rotate a paddle and that is going to shut down our transformer those are the two functions of a gas actuated relay 2 alarm when we have slowly accumulating pockets of gas that are caused by small electrical faults and to shut down when we have sudden large increases in pressure and gas that are created by large electrical faults the book calls relay itself has a third and final feature and that is to shut down the transformer in the event the insulating liquid level becomes low we can see that it's installed between the conservative tank and the main tank if the level was to come down to here we would trip the transformer and that protects the transformer then and ensures that we do not get a catastrophic failure we zoom out you can see that we have different cooling fins on the side of the transformer this time the reason that these cooling things are larger is because we need to get rid of more heat I'll just rotate around the side you can see that we've got a entire radiator this time the liquid enters the top of the radiator it cools down and then it passes out the bottom and we'll have natural convection in order that the process continues and we can cool down the insulating liquid as much as possible we go to the end we can actually see that we've got some fans and these fans will start once the temperature of the insulating liquid becomes quite high you can see now that they're running that means the transformer is heavily loaded and we need to pass air over the heat exchanger or the radiator in order to get a greater cooling effect if the fans are running like this or if we have fans installed we will say that the type of cooling employed is forced-air the second type of cooling that is described would be their cooling associated with the insulating liquid itself in our case we have a natural convection process so this transformer is an oil natural air forced type transformer or Oh n AF as it will be written on nameplate let's go over to the end of the transformer and we can see we've got a control box his control box or control cabinet is used to house some of the associated machinery with the load tap changer the load tap changer is mounted in this section here and this type of tap changer is mounted directly within the transformer tank that's not always the case sometimes the transformer will be mounted externally or perhaps it will have its own compartment within the transformer tank the disadvantage have an attack changer directly within the tank is simply that it shares the same insulating liquid as the transformer that means that when you sample the insulating liquid and start to look for faults or telltale signs such as large amounts of acetylene or ethane you're not going to get much reliable information from your sample if the tap changer is mounted in a separate compartment or externally to the main tank then you can sample the main tank you can then send a sample away for analysis you can look at the gases that are present within the insulating liquid and that will give you a good indication as to what faults if any present within the transformer if we go this way we can actually have a look now at the final piece of the transformer or the final component and that is a temperature indicator and temperature thermometer thermometer has been mounted within the tank we can see it here and the indicator is mounted on the side in order the engineers as they walk past can look at the temperature gauge and assess what it is and if we were operating within normal conditions the red needle itself is used as an alarm set point if the black needle should come around and surpass the red needle we're going to get an alarm the other red needles that we're looking at now are mostly used for cuttings and cut outs for fans and cooling pumps so that was a very brief introduction to transformer components and the three main designs if you like this video then check out the link in the video description area the link leads to a transformer course and if you click on that link you'll be able to purchase the course at a special discount price the video course is far more detailed than the information that I've given in this video and if you really do want to learn more about transformers including theory and maintenance then I really do suggest you check out that link if you like this video then please do like it or share it on social media it really does help us out and allows us to produce more and more content thanks very much for your time [Music]

Channel: saVRee

Views: 264,788

Rating: 4.9375381 out of 5

Keywords: transformer parts and functions, distribution transformer parts and functions, parts of power transformer and their functions, different parts of transformer and its functions, electrical transformer, parts of transformer and its functions, power transformer, distribution transformer, hermetic transformer, conservator transformer, cast resin transformer, transformer types, transformer components, transformer parts, power transformers explained, parts of transformer

Id: 3osmO4FQ2Yg

Length: 27min 50sec (1670 seconds)

Published: Sun Nov 04 2018