What Are the Advantages and Disadvantages of oil Type power transformer and Dry Type Transformer?

 Transmission and distribution transformer oil type transformers are more common in our daily lives. Some power poles, roadsides, etc. have transformers for distribution. The operating conditions of these power transformers are generally relatively simple. Fully sealed oil type power transformers are placed in the open air.

 

The oil type distribution transformer is the same as the dry type transformer. It is a power transformer, and there will be a core for the magnetic circuit to make the winding of the circuit.

 

The biggest difference is in "oil filled" and "dry". That is to say, the cooling medium of the two is different. The former uses transformer oil (and of course other oils such as beta oil) as the cooling and insulating medium, and the latter uses air or other gases such as SF6 as the cooling medium. Oil filled transformer is to place the body consisting of iron core and winding in a fuel tank filled with transformer oil. Dry type transformer often encloses the core and windings with epoxy resin. There is also a kind of non-encapsulated type that is used nowadays. The windings are impregnated with special insulating paper with special insulating paper to prevent the windings or core from getting wet. (Because the two are derived from different categories due to different methods of process, use, and structure, we are narrowly speaking.) In terms of production and usage, the current dry type transformer's voltage rating is only 35kV. The capacity is small compared to oil filled transformer, about 2500kVA. Moreover, since the dry type transformer manufacturing process is complicated and costly with respect to the oil filled transformer of the same voltage level and the same capacity, the oil filled transformer is still much more in terms of the amount of oil. However, due to the environmental protection of dry change, flame retardant, impact resistance and so on, it is often used in indoor and other high-demand power supply and distribution sites, such as hotels, office buildings, high-rise buildings and so on. If you are just a transformer user, it should be enough to understand this.

 

YueBian is one of

oil type power transformer suppliers

in China. Welcome to buy our products.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest dry type transformer manufacturer in China. We provide electrical transformer, oil transformer and etc. Want to buy transformer? Contact us.

 

Utility Transformer Connections

  

Utility Transformer Connections

The transformer can be directly thrown into the transformer room by the car crane, or seting up a temporary track with the daewood, use a three-step and suspension chain to carry the transformer to the temporary track, and then use the chain to pull into the suitable position in the room.

When the transformer is in place, it should be noticed that its direction and distance away from the wall should be in line with the drawing with a permissible error to be ±25 mm. When the drawing is unmarked, the vertical position shall be in place as the track, and the transverse distance from the  wall shall not be less than 800 mm, and the distance from the gate shall not be less than 1000 mm.

 

The shell of power transformer should be reliably grounded. The working zero line and neutral grounding line should be laid separately, and the working zero line can not be buried underground. The place where the neutral grounding loop of the transformer closes to the transformer should be made detachable joint bolts.

 

The transformer with valve type arrester should meet the grounding requirements: the transformer neutral point, transformer shell and arrester should be connected to a common place to ground.

 

The grounding resistance should be ≤4 ohms. The zero line and ground line of the transformer shall be connected separately and shall not be together. The ground line of the transformer is next to the transformer base, and the zero line of the transformer is the N line of the low pressure pile.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest distribution transformer manufacturers in China. We provide step down transformer, oil transformer and etc. Want to buy transformer? Contact us.

Transformer Testing Methods

 Transformer Testing Methods

Different capacity transformers, different measurement methods, different voltage grades, different core structures and so on, their measurement time is different. If the single phase measurement is directly on the low pressure side, it takes 40~50 minutes to measure a phase. For a 150 MVA transformer magnetometer, it takes approximately 3~5 minutes to measure each phase. And if without saturable magnetic circuit, it takes about 30 minutes for each phase. For the high voltage power transformer with a voltage rating of 35 KV, the measurement time of the transformer is greatly reduced and it's not necessary to use the saturable magnetic circuit method. For the three core transformers below 120 MVA, the saturable magnetic circuit method is not used, too. The measurement can be carried out directly within 20 minutes generally. For star connection, measurement data shows that it is stable.

 

Resistance experience: check the resistance of the coils to determine the veracity of the data before DC resistance test. For example, for a large of 240 MVA or 360 MVA, its low voltage side resistance is generally about 1 M Omega or 2M Omega. If without saturable magnetic circuit method, the initial measurement data is about 4 m Ω ~ 10 m Ω and very stable. After about 10 minutes the date begins to get small.

 

The change law of data: in the case of the direct resistance measurement of the low-voltage side of large distribution and power transformers, the first data is far away from the real value, and it is stable for a period of time. Then the date gradually starts to change, bigger or smaller, and the change gets fast. And then the date gradually changes slowly to achieve almost no change finally and get the real resistance. This change tends in one direction, for example, getting smaller and smaller until the real value. If the date is erratic or remains (almost) unchanged for a long time and it's far away from the real value, we should check whether the wiring is wrong.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest oil filled transformer manufacturers in China. We provide distribution transformer, oil transformer, distribution transformer testing, power transformer testing, transformer testing and etc. Want to buy transformer? Contact us.

 

Transformer Megger Test

 Transformer Megger Test

 

The megger has three terminal posts: one for "L", one for "E" and one for "G" (shield). L is connected to the wires, E is connected to the cable, and the "G" is attached to the insulated paper of the cable. The following points should be noted when measuring:

The power must be cut off first.

The megger must be kept flat when used.

Before we use the megger, we need to rotate several times to see whether the pointer is at the largest location. Then we will short-circuit the two terminals of "L" and "E", then slowly turn the hand of mega ohmmeter to see whether the pointer is at zero.

The megger cable must be insulated well, and the two lines shall not be twisted together.

When measuring the megger, the reading should be based on the number after a minute of rotation.

During the measurement, the number of meters should be transferred to 120 revolutions per minute.

The megger has a range of several thousand megaohm, with a minimum scale of about 1 trillion euro, which is not suitable for measuring the resistance below 100 kiloohm.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest power transformer suppliers in China. We provide power transformer, oil transformer and etc. Want to buy transformer? Contact us.

 

Winding Resistance Test Of Transformer

 Winding Resistance Test Of Transformer

The measurement for the temperature of winding

 

The temperature in the channel between the high and low pressure winding passages which is measured by dry type transformer is seen as the temperature of winding;

 

The average temperature between the top and the bottom oil measured by the oil—immersed transformer is seen as the temperature of winding.

 

The selection of measuring current

 

The measuring current can not be over 15% of the rated current of the tested winding;

 

The measuring current should be selected within the range of the testing resistance as stipulated by instrument;

 

The tester for the DCR of transformer:

 

5A       1mΩ—4Ω

 

10A       0.2mΩ—2Ω

 

20A       0.1mΩ—1Ω

 

The measurement of winding resistance

 

According to the point 7 to connect the test line, when we use the magnetic circuit method, the current direction of magnetic winding should be in accordance with that of the same end of the tested winding. On the basis of the point 9.2 of technical conditions of products, when it comes to the power switch of instrument, we should select the measuring current by pressing the mode button and press the start key to measure the winding resistance. After the result becomes stable, record the value. Then press the reset key to discharge off and the measurement ends.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest electrical transformer manufacturers in China. We provide dry transformer, oil transformer and etc. Want to buy transformer? Contact us.

 

Winding High Voltage Transformer

 Winding High Voltage Transformer

In a word, a transformer is a high voltage winding, composed of a copper core or an aluminum core, and a low voltage winding and a core, the high voltage winding is subjected to high pressure, and it has the insulation level under high pressure. Low voltage windings bear and output low voltage, and the principle of electromagnetic induction is known to all.

 

The transformer's high voltage windings are relative to the low-voltage windings, and the primary coils may be high voltage windings or low-voltage windings. Mainly look at the function of transformer. There are many layers of windings because no matter the high pressure area or the low pressure area is determined by the length of the winding conductor of the corresponding thickness, this is also an important factor in determining the volume of the transformer.

 

The input voltage is 10 kV, and the output voltage is 0.22/0.4 kv.

The input end is the high voltage winding, and the output end is the low voltage winding. An ultra high voltage transformer with an input voltage of 500 kV, its output voltage is 110 kV; The input end is the high voltage winding, and the output end is the low voltage winding. The input voltage is 220 V, the output voltage is 12 V, 6 V and so on. The input end is the high voltage winding and the output end is the low voltage winding.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest power transformer manufacturers in China. We provide dry type transformer, oil transformer and etc. Want to buy transformer? Contact us.

 

Transformer Maintenance Guide

 Transformer Maintenance Guide

Check the cleanliness of the casing and magnetic road, and clean up in time to keep them clean and prevent flashover.

When the cooling device is running, make sure that the butterfly valve in the inlet and outlet of the cooler is open and the radiators are open with entrance clean. The steering of the submersible pump and the running condition (no abnormal sound and obvious vibration) should also be checked as well as the operation of fans. Make sure that the automatic power switch of cooler control box is well closed with no vibration and abnormal voices; and the cooler doesn't leak oil.

Ensure that electrical connections are tight and reliable.

Check the tap-charger regularly and check the fastening, burns, scars, rotation flexibility and connecting positions of the contact.

The coil, casing and lightning arrester should be tested every 3 years.

The reliability of the lightning arrester is checked every year. The grounding of the arrester must be reliable, with the lead as short as possible. The ground resistance should be detected in dry seasons, which can not exceed 5 Omega.

Replace the desiccant of respirators and oil used in the oil bath.

Test fire facilities regularly and record the their maintenance and performances in detail.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest power distribution transformer manufacturers in China. We provide power transformer, oil transformer and etc. Want to buy transformer? Contact us.