Each part of your equipment has its own purpose.
For instance, when it comes to generators – the engine provides energy, the exhaust, cooling and lubricating systems ensures overheating doesn’t occur while the fuel system powers the generator.
No matter which component of the equipment it will be – they all play a part. Likewise, a stator core is just as important as any of the parts mentioned above.
While you may know a stator core roughly works, it is always best to know it thoroughly to fully understand your equipment and have it operate for maximum efficiency. For instance, once you spot a problem in the stator core – it might mean that electric motor or generator rewinding is necessary.
Below, you will understand what stator core lamination is and discover its advantages for your equipment.
How does a standard core lamination go about
A typical stator core is made up of countless individual steel laminations – from thousands up to even hundreds of thousands.
As of now, laminations are created by computer-controlled laser cutting machines or stamping/punching dies.
The process of building a stator core goes like this: laminations are continuously placed side-by-side with the objective to attain a ringed or complete circular layer. As such the following layer will continue being laid out – offsetting each layer like a cinder block wall or brick until the desired length and layer is achieved. Generally, a stator core will be estimated to be about 0.014” to 0.018” for each layer – while the length can range from ten to twenty feet.
All these segments/layers are aligned properly and fastened together under compressive loads with parts like finger plates, building bolts, key bars, through bolts and compression rings.
Why is the stator core laminated?
In a case scenario where the stator core is made from solely one solid piece of material – the associated heat produced and currents will amount to a large sum – resulting in a melted stator core.
As such, there is a need to laminate the stator core and insulate each layer. Reason being that the circulating currents will be brought down to a size that is much more smaller and controllable. Hence, allowing the heat generated by the currents to be managed by pumping cooling gases (hydrogen or air) through and/or across the stator core structure.
Simply put, this makes sure that the stator core’s performance is not compromised or even driven to the point of terminal malfunction.
The pros of stator core lamination
Lessens eddy currents (circulating currents)
The stator core comprises an electromagnetic field which produces a voltage, known as circulating current or eddy current.
In most cases, this type of current will result in decreased performance and power loss – caused by several factors like the density of magnetic flux and frequency of electromotive force (EMF).
By insulating the core with stator laminations – there will be lesser eddy currents. Layers of plates are placed on top of one another right in the middle to prevent eddy current flow.
As a result, the reduced eddy current will mean that the stator core is able to keep its constant power and operate efficiently.
Reduces hysteresis loss
Other than producing eddy currents, the electromagnetic field also magnetizes the stator core, also known about as hysteresis.
The continuous cycle between magnetization and demagnetization forms a loop – the bigger it is, the higher the accumulated energy consumed to magnetize and demagnetize the stator core. In other words, when the core produces heat – hysteresis is being lost as well – leading to huge sums of energy and power loss.
Here is where lamination plates come in to prevent such an incident with its narrow hysteresis loops which do the job of magnetizing and demagnetizing the core – by using lesser energy. Which also translates to more efficient equipment.
Cools down the stator core
Having only a solid piece of steel or iron stator core does not only produce huge amounts of eddy currents but also causes it to overheat til melting becomes a guaranteed possibility.
As said earlier on, laminating the stator core reduces the eddy current but also lowers down the heat produced as well.
So, this means that the stator is cooled from time to time – allowing it to function properly without melting.
When should you seek repair or restack?
As time passes, the stator core’s performance will slowly deteriorate. Once you spot signs such as oil contamination or loose bars and wedges in your equipment such as generator – you should get a professional engineer to do generator overhauling – either doing a repair or restacking the stator core’s lamination. Moreover, doing a repair does not only solve any existing issues with the stator core but also boosts the overall efficiency of your equipment.
The key to ensuring maximum efficiency for your equipment at all times is by understanding how your equipment – be it transformer, electric motor or generator – works. In this case, the stator core is a crucial component – that if not looked after properly – will result in a complete malfunction of your equipment. So, know how stator core lamination goes about; you will understand your equipment better and know when its time to do generator maintenance.