Power Transformer Winding

 Power Transformer Winding

 

 

The power transformer is a static electrical device, which is used to transform a numerical value of alternating voltage (current) into other voltage (current) with same frequency or several voltage (current) in different value. The rated voltage of the secondary winding of a power transformer refers to the no-load voltage of the secondary winding when the transformer winding is under the rated voltage.

 

When the transformer is at full load, the impedance of the primary and the secondary winding of the transformer will cause the voltage drop of the transformer itself, which is equivalent to 5% of the rated voltage of the power grid, so that the terminal voltage of the secondary winding is smaller than the no-load voltage. In order to compensate for the voltage loss in the line, the rated voltage of the secondary winding of the transformer should be higher than the rated voltage of the power grid by 5%. Therefore, the rated voltage of the secondary winding of the transformer is 10% higher than the rated voltage of the same-level power grid.

 

When the transformer is put into practice and the power supply radius is smaller, the voltage loss of the line can be ignored since the line is relatively short. At that time, the rated voltage of the transformer's secondary winding should be 5% higher than the rated voltage of the grid to compensate for the voltage loss of the transformer itself.

 

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest electrical transformer manufacturers, we provide power transformer, distribution transformer, step down transformer, oil transformer, electrical transformer and etc. Want to know more? Please contact us.

 

Pole Mounted Transformer Connections

 Pole Mounted Transformer Connections

 

When Installing this transformer, remember the transformer should be at least 3M higher than the ground. Besides, the distance between the drop fuse and the ground should be over 4.5M, and the arrester and drop fuse should keep a distance of over 0.8M. The protective grounding must use more than 25 squares of stranded copper wire. Shared copper wires are prohibited in grounding.

 

Specific descriptions are:

How do you assemble a transformer on a 15-meter pole?

 

You can choose a ring with a diameter of 300mm, M20*100 and M20*350 screw, D200 channel steel to produce framework, and choose a 63*6 equal angle steel to make crossarm. The diameter of the installation position is determined at the scene, the root of which should be more than 2.5M. The equal diameter rod can be used to support the middle part.

 

Select the electric pole as follows:                                                            

1. A complete 15cc-15m dial diameter with the tailed diameter accounts for 1.25% of the length. 15*1.25=18.75+15=33.75 (head diameter of the rod)

 

2. To weld a 19cc-9m rod, with 1.25% tail length with a equal-diameter rod with a diameter of 30cc*. Use one one of them to connect the ground pile.

 

There are also many poles that can not install transformers, such as poles below 8 meters high (8 meters in not included). Because the pole should be buried 1.5-2.0 meters deep, the base of  the transformer should keep a safe distance of 2.5M. Besides, enough room should be guaranteed for the incoming lines.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest power transformer suppliers, we provide power transformer, distribution transformer, step down transformer, oil transformer, electrical transformer and etc. Want to know more? Please contact us.

 

Overview of Various Classifications of 10kV Transformers

 1. Transformer overview

The 10kV transformer is referred to as "distribution". It refers to a kind of static electric appliance in the distribution system that converts AC voltage and current according to the law of electromagnetic induction and transmits AC electric energy. A 10kV transformer is usually a power transformer that operates in the distribution network with a voltage rating of 10-35kV (mostly 10kV and below) and a capacity of 6300KVA and below directly to the end user.

 

2. Sorted by installation location

The 10kV transformer is divided into indoor and outdoor depending on the installation location. Outdoor installation is divided into platform type, tower type and floor type (including pre-installed type).

 

2.1 pole tower

The tower type is a structure in which a transformer is mounted on a pole. It is divided into single pole and double pole.When the 10kV transformer capacity is 30KVA or less (including 30KVA), a single pole 10kV transformer gantry is generally used. Install a 10kV transformer, high-voltage drop fuse and high-voltage arrester on a cement rod. The shaft should be tilted 13°-15° in the opposite direction of the assembled 10kV transformer.

 

When the 10kV transformer capacity is between 50KVA and 315KVA, a double-pole 10kV transformer station is generally used. The 10kV transformer stage consists of a main rod cement rod and another auxiliary rod. The main pole is equipped with a high voltage drop fuse and a high voltage down conductor, and the secondary pole has a secondary reverse lead. The double pole 10kV transformer stage is sturdy with a single pole 10kV transformer.

 

The advantages of the tower type installation: the land occupation is small, the surrounding wall does not need to be fenced or covered, and the charged part is higher than the ground, which is not easy to cause accidents.

Disadvantages: The rack needs more steel and the cost is higher.

 

2.2 Pier type

The pier type is a square pier with 0.5-1 m masonry under the transformer pole, and the transformer is placed on it. Generally, a transformer of 315KVA or more is installed.

 

Pay attention to the following three points when installing a pier type transformer:

 

(1) A solid barrier or masonry wall of not less than 1.8m shall be installed around the transformer. The door shall be locked and kept by a special person.

(2) The barrier and fence should have sufficient safe operating distance from the transformer.

(3) Warning signs such as "high-pressure danger, no climbing" should be hung on poles or fences to prevent people and animals from approaching.

 

Advantages of the pier type installation: it is low in cost and easy to maintain and repair.

Disadvantages: It occupies a large area, and it is necessary to install a fence around it. Small animals are easy to climb to the charged part, which is prone to damage caused by external forces.

 

2.3 Floor type

Floor-standing means that the transformer is placed directly on the ground, and the high-voltage down-conductor, the drop-out fuse and the arrester are all on the line terminal rod. Pay attention to the following three points when installing a floor-standing transformer:

(1) A reliable fence must be installed around the transformer. The door should be locked and kept by a specific person.

(2) Warning signs such as "high voltage danger, no climbing" shall be hanged outside the fence.

(3) Since the live part of the transformer is very low from the ground, the person must enter the barrier after cutting off the power.

 

3. Classified by cooling method

According to the cooling method, it can be divided into oil-immersed and dry-type transformers.

Oil-immersed transformers rely on oil as a cooling medium, such as oil-immersed self-cooling, oil-infiltrated air-cooled, oil-immersed water-cooled, forced oil circulation, and the like. Dry-type transformers rely on air convection for natural cooling or increased fan cooling. They are used in small-capacity transformers such as high-rise buildings, high-speed toll stations, and local lighting and electronic circuits.

 

3.1 Oil-immersed transformers are divided into:

1) Non-closed oil-immersed transformer: It mainly has S8, S9, S10 and other series products, which are widely used in industrial and mining enterprises, agriculture and civil buildings.

2) Closed-type oil-immersed transformer: It mainly has S9, S9-M, S10-M and other series of products, which are mostly used in places with multiple oil and chemical substances in petroleum and chemical industries.

3) Sealed oil-immersed transformer: It mainly has BS9, S9-, S10-, S11-MR, SH, SH12-M and other series products, which can be used for power distribution in industrial and mining enterprises, agriculture, civil buildings and other places.

 

3.2 Dry type transformers are divided into:

1) Encapsulated coil type dry-type transformer: It mainly has SCB8, SC(B)9, SC(B)10, SCR-10 and other series products, suitable for high-rise buildings, commercial centers, airports, stations, subways, hospitals, factory and other places

2) Non-encapsulated coil dry-type transformer: It mainly has SG10 series products, suitable for high-rise buildings, commercial centers, airports, stations, subways, petrochemicals and other places.

 

4. Electric voltage regulation

According to the voltage regulation method, it can be divided into on-load voltage regulation and no-load voltage regulation.The so-called no-load voltage regulation and on-load voltage regulation all refer to the transformer tap changer voltage regulation mode. The difference is that the unloaded regulator switch does not have the ability to load shift gears, and the transformer must be powered off when shifting. The on-load tap-changer can be switched with load.

 

5. Phase number classification

According to the number of phases, it is divided into single-phase transformer and three-phase transformer.A single-phase transformer is a transformer in which the primary winding and the secondary winding are single-phase windings. The single-phase transformer has a simple structure, small volume and low loss, and is mainly small in iron loss, and is suitable for application and promotion in a low-voltage distribution network with a small load density.

 

Three-phase transformers are used for the rise and fall voltages of three-phase systems. For a three-phase transformer, there are generally three primary windings, which are divided into triangles and stars, and extended triangles. The voltages on the three windings are 120 degrees out of phase, which is the common three-phase 380 volt connection. The core of the iron core is a three-phase three-core column, a three-phase five-core column, and an involute shape.YueBian Electric Co.,Ltd is a professional 10kv oil transformer supplier. Welcome to purchase.

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest power distribution transformer manufacturers, we provide power transformer, distribution transformer, step down transformer, oil transformer, electrical transformer and etc. Want to know more? Please contact us.

 

Oil Filled Transformer Maintenance

 Oil Transformer Maintenance

 

 

Overhaul projects:

 

Removal of the hanging core or hanging cover for each accessory.

 

Maintenance of winding, lead devices and other equipment.

 

Maintenance of tap chargers.

 

Overhaul of iron core, core piercing screw, yoke beam, nail and ground piece.

 

Cleaning and maintenance of oil tank, casing, radiator, safe airway and expansion tank.

 

Testing of transformer equipment such as oil purifier, respirator, expansion tank capsule and releaser.

 

Inspections and maintenance of gas relay and thermometer.

 

Drying of the transformer when necessary.

 

Replacement of all seal pads and leaking test for components.

 

Inspections and cleaning for the air porcelain.

 

Oil treatment of transformers.

 

Regular inspections and test.

 

Minor repairs:

 

Clean the shells.

 

Check and eliminate defects that have been found.

 

Clean the casing and tighten the wiring bolts of each casing.

 

Inspect expansion tank and oil level gauge.

 

Check the respirator and oil purifier, and replace the silicone when necessary.

 

Repair the submersible pump and the cooling fan of coolers.

 

Check the connection of the joints, valves and seal pads.

 

Repair gas relay and thermometer.

 

Check and debug the voltage regulator, measuring device and control box.

 

Analyze samples, and adjust oil level of casings and the transformer.

 

Clean and paint oil tank as well as accessories.

 

Conduct measurement and test according to regulations.

 

Clean the air porcelain.

 

High-voltage test.

 

 

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest dry transformer manufacturer, we provide power transformer, distribution transformer, step down transformer, oil transformer, electrical transformer and etc. Want to know more? Please contact us.

 

Overhead Transformer Connections

 Overhead Transformer Connections

 

 

1. The distance between the wire of distributing line and pole or framework: at least 0.3m per 10kV and 0.1m per 0.4kV.

 

2. The net distance between lead wire, downlead in each phase and the lead wire or downlead of next phase: at least 0.3m per 10kV and 0.1m per 0.4kV.

 

3. The lapping zone of distributing line's downlead and overhead insulated line should be connected in T type clamp or insulating parallel groove and covered in insulating materials. Besides, use waterproof tape and self-adhesive insulating tape, corresponding to the voltage classes, in the joint of insulating wine and insulating cover, so that it can be waterproofed and dust-free.

 

4. The ground downlead should connect with the middle points of low voltage sides and the corresponding shells. After that, earth it again with the ground resistance below 10 ohm. In case the needs can not be met, you need to add the length of vertical and horizontal grounding objects.

 

5. The mounting height of pole distribution transformers and switch boxes should not lower than 3m.

 

6. Under the premise of satisfying the requirement of phase, the drop-out fuse should be installed on the highway side.

 

7. Before installing equipment, the mounting hole size should be checked carefully. If it doesn't match the installation drawing, you should contact with the design unit in time to let the problem properly solved.

Yuebian Electric Co.,Ltd, approved by ISO9001, is one of the largest electrical power transformer manufacturers, we provide power transformer, distribution transformer, step down transformer, oil transformer, electrical transformer and etc. Want to know more? Please contact us.