The Ultimate Guide to Dead Front Transformers

We know more about the dead front transformer is the dead pad mounted transformer, which has been widely used in North America.


Daelim Transformer is a professional transformer supplier located in China. The professional technical team can design pad mount transformer that fully complies with ANSI/EEE, DOE, CSA, AS/NZ, and other international standards. It has SGS, CESI, IEEEC 57, IEC60076, CSA C88, and other transformer test reports, as well as UL, and cUL certificates.

Table of contents
1. What is a dead front transformer?
2. Are dead front transformers fully insulated?
3. What are the types of dead-front transformers? 4. What is the difference between single-phase and three-phase dead front transformers?
5. What are the loop feed transformer and the radial type feed transformer difference?
6. What is the application of dead front transformer?
7. What is a live-front transformer?
8. What is the difference between live front and dead front transformers?
9. What are the CSA standard specifications of the pad mounted transformer?
10. Dead front transformer custom and for sale

What is a dead front transformer?

Before understanding the concept of dead front transformer, we must first understand the "partition". Due to the before death front transformer belongs to the partition type.


Pad transformer structure is composed of two parts before and after. The front end is the wiring control board of the transformer, which can adjust the voltage, switch, oil temperature, oil level, etc. On the back is the transformer mailbox containing transformer core, windings, high voltage load switches, external fuses, transformer oil, etc. The voltage grade of the product is 34.5kV, belonging to the distribution transformer.

 

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"Post-death transformer" is the radial feed that seals the high voltage bushing and current-carrying parts of the transformer with rubber material. It is usually composed of a bushing well, a break load insert,s, and a break load elbow, so it is completely insulated. Safety improvements that do not expose load current elements.


There are two kinds of the transformer before dead front transformer, one is loop feed, and the other is radial feed. The three-phase loop feed transformer is composed of 6 high voltage bushings, and the three-phase RF is 3 high voltage bushings. The single-phase dead-front transformer has two high voltage bushings. You can choose according to your actual needs.


The transformer uses the backup fuse and the Bay-O-Net fuse in series to provide protection, the backup fuse is installed in the box inside, only in the pad-mounted transformer internal phase fault action used to protect the high voltage line, and the Bay-O-Net fuse in the secondary side short circuit or overload when the fuse.
The high voltage cable is connected to the bushing with good insulation performance, the bushing is connected to the elbow-type cable plug, and the live part is sealed. The elbow-type cable plug is a fully shielded insulation plug, which can be inserted and removed with full load, equivalent to the load switch, Its dead front structure is shown below, but if it is closed to the breaking point, both the elbow-type plug and the bushing should be replaced.

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Are dead front transformers fully insulated?

My experience is that pad mounted transformers and their definitions are easy to understand. If you open the second side, you'll see an exposed busbar, which is a charged front end. If you see an insulated elbow joint, that's a blind spot.


In general, "live front" means "power on," "easily," "death," and "trying to kill the" pry "from the" master."


The live front transformer has the power supply on it and the primary cable is exposed, whereas the dead front transformer without power supply has an insulated elbow.

 

Read more: What is a Live Front 25kv Pad-Mounted and Substation Transformer Specification?


What are the types of dead-front transformers?

There are two types of dead-front transformers. Single-phase and three-phase transformer


Three-phase transformer

Three-phase transformer balanced three-phase alternating current (ac) is input, the output three-phase symmetric alternating current (ac), it can be for three-phase electric industrial electrical equipment, such as three-phase ac asynchronous motor, three-phase power supply, can only need single phase electric civil electrical appliances, such as light bulb color TV, single-phase power supply three phase four wire system to provide the power supply.


Balanced three-phase alternating current (ac) 2, the three-phase transformer is input, the output three-phase symmetric alternating current (ac), it can be for three-phase electric industrial electrical equipment, such as three-phase ac asynchronous motor, three-phase power supply, can only need single-phase electric civil electrical appliances, such as light bulb color TV, single-phase power supply three phase four wire system to provide the power supply.


Single phase transformer

However, the single-phase transformer is the input single-phase AC, the output single-phase AC, but it can only provide single-phase power supply for the load that needs single-phase electricity. If there are three single-phase transformers connected to each other, it can also provide three-phase power.
Single-phase transformer, generally refers to the primary coil designed in accordance with the single-phase single-coil, the secondary can have one or more winding coils, ideally, total secondary power is about or equal to the primary total power. For example, the standard primary power supply low voltage of 220 volts, and the core is made of mouth type, day type, ring, and R shape.

 

Learn more about dead front transformer: Single phase and Three phase pad mount dead front transformer


What is the difference between single-phase and three-phase dead front transformers?

In terms of structure, the most common is three-phase dead front transformer and single-phase dead front transformer. The high and low voltage side of the three-phase transformer needs three coils, and the three coils of the high and low voltage side are connected according to certain rules. This is the connection group of the transformer. There are many kinds, such as YNn0, Dyn11, which can provide users with the power they need.


The high and low voltage sides of the single-phase transformer only need one coil, respectively connected to the power supply and load.

 

There are three or six high-voltage bushings on the high-voltage side of a three-phase dead front transformer and only two high-voltage bushings on the high-voltage side of a single-phase dead front transformer.

 

The cover of the 3-phase dead front transformer is generally opened on the side, and the cover of the single-phase transformer is opened from the top.

 

The conventional capacity of 3-phase dead front transformers can be up to 5000kva, and the conventional capacity of single-phase transformers can be up to 250kva.

 

The voltage level of the 3-phase dead front transformer and the single-phase transformer is the same up to 34.5kV.

 

In other aspects, the iron core of the three-phase transformer is flat "day" type, providing three magnetic circuits for three-phase electricity, and the iron core of the single-phase transformer is "mouth" type, which has only one magnetic circuit.

 

Try for free: How to choose pad mounted transformer for Crypto Mining?

 

What are the loop feed transformer and the radial type feed transformer difference?

Pad mounted transformer can be divided into radial type and loop feed type according to its purpose. radial type mainly distributes electric energy to low voltage power users. The loop feed type is also used for ring network function and power distribution, Loop feed type generally has more than two incoming lines.
Loop feed and radial type pad mounted transformer difference is mainly reflected in the high voltage inlet and outlet, loop feed type transformer in addition to the high voltage outlet of the transformer itself, there is another high voltage outlet, the formation of loop feed type power supply; Radial feed pad-mounted transformer has only the high voltage outlet for its transformer.


Loop feed type pad-mounted transformer allows users to obtain power from two directions. The power supply network is usually connected to a ring to provide stability to the power supply. This power supply mode is referred to as ring power supply. Box substation with loop feed power supply is called ring box transformer, which is located at the middle-end of the bus trunk system.


Radial type pad-mounted transformer only appears for its own transformer high voltage, placed at the end of the busbar trunk system, relative to the loop feed pad-mounted transformer, the use of one inlet and outlet cabinet, and loop feed pad mounted transformer at least two outlet cabinet.


Loop feed type pad mounted high voltage using loop feed cabinet, the so-called ring network cabinet is each distribution branch set a switch cabinet, the switch cabinet bus is also a part of the loop feed trunk. The ring trunk is composed of the busbar connected by each outlet cabinet.


The number of loop feed transformer high voltage cabinets is more than that of radial feed pad mounted transformer, and the shell size of pad mounted transformer is larger, so the cost of loop feed transformer is much higher than that of radial feed transformer substation.

 

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What is the application of dead front transformer?

The dead front transformer is a kind of distribution transformer. The dead front transformer is a kind of distribution transformer.


It can be used in residential areas, shopping malls, industries, schools, encrypted mines, skid pad mounted substations, and other places.


Because they have high voltage and low voltage closed safety compartments, they operate safely and prevent the occurrence of public accidents. Pad type is an outdoor in-cabinet device with medium pressure stop head and a locking door. In order to overcome the ferromagnetic effect, a primary transformer is used as the power supply. The transformer has two main types of construction: radiation type and ring network type (depending on the type of line installed in the transformer). In the radial arrangement, the transformer is connected to the primary power supply and can not be used for the primary power supply. Grid structure. The system features a transformer connected to a primary power supply, which can provide electricity for other loads.

 

Keep reading: Skid mount transformer solution with3 phase pad mounted transformer inside


What is a live-front transformer?

To put it simply, a Live front is a cable terminal that is connected to the transformer wall outdoors with a ceramic sleeve. In Dead Front, the cable is connected to the casing well, which is a load break plug. First, bushing is a slot wall that allows a wire to pass through a transformer without electrical contact. So, what about looper? It is called Live because its terminals are actually open to the outside world. There's an electric current going through it.

 

Keep reading: How Do I Choose A 1500kva Transformer In 2022?


What is the difference between live front and dead front transformers?

A transformer is made up of many parts. Inside this is a device called bushing. These parts are attached to the innermost part of the motor to provide a supporting surface for the rotating parts. These sleeves can be Livfront or Dead Front.


Live front refers to the bolt fastening and pressure cone. When you open the door, the intermediate pressure is at the end. "Dead edge" refers to the terminal using molding; the load breaks through the elbow, and there is a real endpoint in the process.


In simple terms, the end of the cable is a porcelain sheath between the outside and the transformer. At the front end, the cable connects to the casing well, which is a load separation plug. For information only, only the high voltage end (13.2 kV) is part of this term. LV (480 V) generally adopts plug mode.


Overall, live front means the energized parts are readily accessible, and dead front means that an attempt has been made to keep prying hands from getting their owner killed. My experience is with pad-mounted transformers, and the definitions are pretty much self-explanatory.


Simply put, the difference between dead front and live front transformers is mainly the difference in high-voltage bushings. The high-voltage bushing of the dead-front transformer is fully insulated for higher safety. The high voltage bushing of the LIve front transformer is not completely insulated and there is a risk of electric shock when current flows.


What are the CSA standard specifications of the pad mounted transformer?

CSA standards for transformers are a requirement to enter the Canadian market. CSA standard for three-phase 60 Hz pad-mounted transformer. The capacity is below 3000kV•A, the insulation level is below 18kV. Transformers are suitable for outdoor mounting on mats without the need for additional protective enclosures.

 

Read my article on How To Purchase 3000kVA Transformer In USA & Canada?

 

The CSA standard has made clear instructions on the Electrical characteristics, Mechanical characteristics, Bushings, terminals, and grounding, Tests, Quality of work and finish, Markings, Optional items, Packaging, etc. of transformers.

 

1. Physical sizes of transformers

Rated kVA capacity Type of feed Transformer maximum BIL, kV Width, mm
75, 150 Radial 95 1280
75, 150, 225, 300 Loop 95 1480
75, 150, 225, 300, 500 Radial 125 1480
75, 150, 225, 300, 500 Loop 125 1480
750, 1000, 1500, 2000, 2500, 3000  Radial 125 1730
750, 1000, 1500, 2000, 2500, 3000  Loop 125 1730


2. High-voltage electrical characteristics of transformers and assembled load-break terminals

Transformer Assembled high-voltage load-break terminals, 200 A
Insulation class, kV                Preferred rated voltage, V               BIL, kV Recommended voltage rating, kV (rms) BIL, kV
5 4 160GrdY/2 400 60  8.3/14.4* 95
5 4 160 60  8.3/14.4* 95
8.7 8 320GrdY/4 800 75 8.3/14.4* 95
8.7 8 320 75  8.3/14.4* 95
15 12 470GrdY/7 200 95   8.3/14.4 95
15 12 470 95 95  8.3/14.4 95
15 13 860GrdY/8 000 95 8.3/14.4 95
15 13 860  95 8.3/14.4 95
18 24 940GrdY/14 400  125 15.2/26.3 125
18 27 600GrdY/15 935 125 16.2/28.0 125


3. Preferred low-voltage and required BIL rating

Insulation class, kV  Rated voltage, V  BIL, kV
1.2 208Y/120* 30
1.2 480Y/277 30
1.2 600Y/347 30


4. Minimum transformer impedance

Transformer size, kV•A  Minimum transformer impedance, %
0–150  1.8 
225 –300  2.0 
500 3.0 
750–1000  4.0 
>1000  5.0 

 

Read more: Knowing More about A Pad Transformer


Dead front transformer custom and for sale

Daelim is a top pad mounted transformer supplier in China. A professional technical team can design various standard dead-front transformers. The highest voltage level of conventional transformers is 34.5kV, and the capacity is 3000kva. Daelim's dead-front transformers can be customized according to your needs and technical parameters. The highest voltage level can reach 44kV, and the capacity can reach 10MVA. If you have transformer requirements or technical problems, you can contact the Daelim team to give you the most complete solution and a detailed price list.


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