Several Types of Transformer

Laminated Core Transformer

This is the most common type of transformer, widely used in appliances to convert mains voltage to low voltage to power electronics. 1.Widely available in power ratings ranging from mW to MW 2.Insulated lamination minimizes eddy current losses 3.Small appliance and electronic transformers may use a split bobbin, giving a high level of insulation between the windings 4.Rectangular core 5.Core laminate stampings are usually in EI shape pairs. Other shape pairs are sometimes used 6.Mu-metal shields can be fitted to reduce EMI (electromagnetic interference) 7.A screen winding is occasionally used between the 2 power windings 8.Small appliance and electronics transformers may have a thermal cut out built in



Toroidal Transformer

Doughnut shaped toroidal transformers are used to save space compared to EI cores, and sometimes to reduce external magnetic field. These use a ring shaped core, copper windings wrapped round this ring (and thus threaded through the ring during winding), and tape for insulation. Toroidal transformers compared to EI transformer: 1.Lower external magnetic field 2.Smaller for a given power rating 3.Higher cost in most cases, as winding requires more complex and slower equipment 4.Less robust 5.Central fixing is either 6.Overtightening the central fixing bolt may short the windings 7.Greater inrush current at switch-on

Autotransformer

An autotransformer has one winding which is tapped at some point along the winding. Voltage is applied across a portion of the winding, and a higher (or lower) voltage is produced across another portion of the same winding. The power rating of the autotransfomer is lower than the load power rating. For example, an auto transformer used to adapt a 1000 VA load to a 240 volt supply is rated at: (240V-120V)/240V x 1,000VA = 500VA. For voltage ratios not exceeding about 3:1,an autotransformer is cheaper, lighter, smaller and more efficient than an isolating (two-winding) transformer of the same rating.[2] Large three-phase autotransformers are used in electric power distribution systems, for example, to interconnect 33 kV and 66 kV sub-transmission networks.

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Daily Maintenance of Transformer

Installation and Operation of Transformer

The installation place of the transformer should adapt their design and construction standards. If it is placed outdoor, you should determine if the EI transformer is suitable for outdoor running. You should protect the transformer from lightning, and the risk of external damage. In addition to ensure that the load is within the allowable range in the design of the transformer. In addition, the top oil temperature in the oil-cooled transformers needs to be carefully monitored. And in the usual running operation, it should be strictly performed in accordance with run operating procedures to prevent misoperation. In the operation of the transformer, we should prevent the phenomenon of overvoltage. Regular checks and inspections are needed to find out the problems, and the problems should be solved timely.

Inspection of the Oil in Transformer

The dielectric strength of the transformer oil decreases sharply with the increase of moisture. One ten thousandth of the water in the oil can reduce nearly half its dielectric strength. Except small distribution circuit board transformer, all transformer oil samples should be kept for puncture test to ensure proper detection of moisture and it should be removed by filtration. Fault gas analysis should be carried out in oil. Eight kinds of faults gas monitor in the application of transformer oil should continuously measure the oil content dissolved in the oil, the type of fault can be determined by analysis of the gas type and content. The physical properties of the oil should be tested every year to determine its insulation properties, and tests include the dielectric breakdown strength, acidity, interfacial tension, and so on.

Regular Maintenance of Transformer

Firstly, maintain the porcelain casing and insulators clean. Secondly, ensure electrical connection reliable and fastening. Thirdly, check the tap regularly. And inspect the contact fastening, burns, scars, rotation flexibility and positioning of contact. Fourthly, in the oil cooling system, check whether there are radiator leaks, rust, dirt or any mechanical damage of on restrict the free flow of oil. Fifthly, test the reliability of arrester annually. Grounding must be reliable, and the leads should be as short as possible. The grounding resistance should be detected during the dry season, and its value should not exceed 4Ω. Sixthly, dielectric loss of the transformer coil, casing and arrester detection should be tested every three years. Seventhly, online detection system should be considered to be used in the most critical transformers. Currently there are a variety of online detection systems on the market and the suppliers will assemble different detectors and sensors, and connect them to the data acquisition device. We should combine the system with the real gas content to guarantee the safe operation of transformer.

This article is come from:http://cell.battery-products.com/ei-transformer/daily-maintenance-of-transformer.htm

Tips for Buying Mains Transformer

The mains transformers are widely applied to convert mains voltage to lower voltages, low voltage lighting in particular. You may find that there are huge amount of makes and models for your option when you purchase your EI transformer. Here we would like to give you some tips before your purchase.

Firstly, ensure the transformer outputs the low voltage you demand. A very widespread type is definitely the 12v transformer (one that outputs 12v) but a lot of other voltages can be found. You won't do any damage if the voltage is lower than that necessary for your purpose, but it may not operate very effectively. On the other hand, in the event you feed 24v to something that demands 12v, you may damage the electronics heavily, so this is advice to get ideal mains transformers.

Secondly, know the energy rating of something you want to power. If it's halogen light bulbs, determine the amount of watts are consumed by each bulb and multiply that with the number of bulbs you are going to be making use of. That is definitely the minimum electrical power rating on the mains transformers you require. An excellent rule of thumb will possess small headroom in the electrical power, meaning that you could possibly have no less than 50% more energy out there in the transformer than you think you need. If your light bulbs consume 100 watts, then get a 150 watt transformer at the extremely least. You never know if someone in the long term will put more electrical power hungry bulbs in the technique, without the need of taking the capabilities of the transformer into consideration.

Thirdly, make sure what type of voltage you may need - AC or DC? A transformer only can output AC voltage, so if you require DC, what you truly want is actually what is called an energy supply. This can be a mains transformer and some added electronics. Also, do you need bipolar or unipolar outputs? A bipolar transformer has 3 output pins, which are known as the positive, the negative and common (ground). A unipolar transformer only has the positive and the common - this style is what's generally sold as a lower voltage lighting transformer, among other things.

Last, safety is another factor to be considered when installing the electronically appliance. The perfect solution is to ask a trained electrician or technician to install the transformer for you, however many people also can get the installing EI transformer done. Except one aspect – You should employ a professional to connect the transformer to the mains voltage. You must be careful that the mains voltages are lethal and very thick to function with components with low voltages.

This article is come from: http://cell.battery-products.com/mains-transformer/tips-for-buying-mains-transformer.htm