This article aims to introduce power transformers. We will introduce power transformers through several common questions. Power transformers are indispensable electrical equipment in power systems (click to learn about the history of transformers). They transmit electrical energy between two or more circuits through electromagnetic induction: electricity generates magnetism and magnetism generates electricity.
power transformer
some questiones you may have interested in
the principle that power transformer work with:
The working principle of the transformer is electromagnetic induction, but strictly speaking, it is because of the mutual induction phenomenon. The following is an explanation of the induction law and the mutual induction phenomenon:
Principle of electromagnetic induction: When the magnetic flux associated with the coil changes (or we can understand that the magnetic flux passing through or through the coil changes), the coil will induce an electromotive force (electromotive force is a physical quantity used to characterize the power supply, commonly known as current), and when the magnetic flux passing through the coil keeps changing continuously, this induced electromotive force (induced current) will be generated continuously accordingly. This is the most intuitive explanation of "electromagnetism".
Specifically, according to Faraday's electromagnetic induction principle, the amplitude of the induced electromotive force (induced current) is proportional to the rate of change of the magnetic flux passing through the coil. We can explain this statement more intuitively in a mathematical way, 
, where E is the induced electromotive force, N is the number of turns of the coil, and 
is the rate of change of the magnetic flux.
Let's look at mutual inductance: the changing alternating current in the primary coil generates a changing magnetic field, and the changing magnetic field passes through the secondary coil, which induces an electromotive force in the secondary coil, that is, an induced current: EMF. Mutual inductance is a direct result of Faraday's law.
Transformers are the best example of mutual inductance, and we define it as follows: when a changing current in one coil induces an electromotive force (current) in another adjacent coil, the phenomenon that occurs is called mutual inductance (which is what we commonly call "electricity generates magnetism, magnetism generates electricity").
In detail, according to Lenz's law, the current generated by the mutual inductance between two coils is affected by the mutual inductance coefficient (the mutual inductance coefficient (M) quantifies the degree of mutual inductance between the two coils), which is measured in Henry (H) according to electronic data. The mutual inductance of the two coils is the same. 
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The main functions of power transformers include:
Voltage conversion: Power transformers meet the needs of different power systems by stepping up or down. Compared with low-voltage current, high-voltage current has the characteristics of low loss and fast transmission speed in the same transmission medium. Therefore, in long-distance transmission circuits, we always use step-up transformers to increase the current voltage, and then send it to the power consumption area, and then step down the voltage through step-down transformers, and then the distribution lines supply power to nearby lines.
Isolation: Due to its internal insulation characteristics, power transformers determine that it can provide electrical isolation between different parts of the power system, thereby improving the safety of the entire power system and reducing the risk of electrical failures.
Efficiency: Power transformers are designed to achieve high efficiency and minimize energy losses during voltage conversion (click to learn why power transformers have low losses).
Structure: The two main structures of power transformers are the core (usually made of laminated silicon steel sheets) and the winding (made of copper or aluminum). The core is responsible for magnetic flux in the power transformer, while the winding is responsible for induced voltage. Compared with aluminum, copper has lower current loss, but due to price reasons, transformers with aluminum windings still occupy a large share in the market.
Application: Power transformers are used in various applications, including substations, industrial plants, and power generation facilities. Due to the rise of virtual currencies such as Bitcoin, the role of power transformers in the "mining industry" cannot be ignored. At the same time, the application and demand for power transformers in industries such as artificial intelligence are also expanding. Yawei Transformer can provide you with professional technical application consulting services.
In short, a power transformer is a static power conversion device that is critical to the reliable distribution and transmission of electrical energy in power systems.
What does a power transformer look like?
Hare the pictures about the power transformers:
What does a power transformer do?
Let me talk about the specific functions of power transformers:
Long-distance power transmission: When we want to transmit electricity over long distances, it is definitely not possible to use low-voltage current, because low-voltage current in the circuit is not only slow, but also has higher heat loss due to the slow speed and resistance in the circuit. In order to avoid this result, we can use power transformers (step-up transformers) to increase the voltage to reduce the current on the transmission line, thereby reducing the energy loss caused by resistance during transmission. By using step-up transformers, we can enable electricity to be efficiently transmitted from power plants to power consumption areas far away from the power source. (Regarding the issue of enameled copper wire and enameled aluminum wire, Yawei transformers are also trustworthy)
Adapt to load requirements: Different electrical equipment and systems have different voltage requirements. Power transformers can convert high-voltage electrical energy into low-voltage electrical energy (step-down transformers) suitable for specific equipment or systems to ensure the normal operation of the equipment. For example, low-voltage equipment and high-voltage poles used in daily life are good reference objects: high-voltage poles are part of the power system, and their voltage is usually higher than the voltage of our daily electrical equipment due to transmission requirements, but our daily electrical equipment does not need such a high voltage. So we need to step down the current. The act of distributing the electricity from the high-voltage transmission line into the transformer and then stepping it down is also called distributing electricity. In the distribution network system, the transformer can convert the high-voltage electricity from the main line (usually from the high-voltage pole) into low-voltage electricity suitable for home and industrial use. By using step-down power transformers, we can ensure the safe use of electricity resources by end users. (Yawei Transformer can provide free, professional power engineering consulting services)
Improve system stability: In the power system, power transportation usually has voltage fluctuations and other situations. Appropriate voltage conversion through transformers can improve the stability of the power system and reduce the risk of equipment damage or unstable operation caused by voltage fluctuations. Achieve improved power quality because proper voltage conversion can reduce harmonics and other power quality issues, thereby improving the overall performance of the power system.
How to test a transformer without power?
There are several methods for testing power transformers without power, mainly focusing on insulation resistance and continuity testing. Here are some common methods for testing power transformers:
1. Insulation resistance test
Purpose: Check the insulation reliability between the power transformer winding and the iron core to determine whether it meets the safety standards.
Equipment: Use a megohmmeter (insulation tester).
Steps:
Connect the megohmmeter wires to the primary and secondary terminals and the ground wire of the transformer respectively. Then use the megohmmeter to measure the insulation resistance values and read them. Based on the safety factor, the displayed value on the megohmmeter should be greater than 1 megohm. Accordingly, the higher the resistance value displayed by the megohmmeter, the better the insulation performance between the winding and the iron core, and the higher the insulation reliability of the transformer. (The quality of Yawei transformers is always worthy of your trust)
2. Continuity test
Purpose: Check whether the conductivity of the winding is consistent with the requirements shown in the technical parameters.
Equipment: Use the resistance (Ω) position of the multimeter.
Steps:
First, use a multimeter to measure the resistance between the primary terminals of the power transformer, and then measure the resistance between the secondary terminals. Make sure that the resistance reading of the multimeter is within the expected range (this is related to the specifications of the transformer and there is no absolute reference value).
3. Turns Ratio Test
Purpose: To check the turns ratio between the primary and secondary windings of the power transformer and verify that the result is consistent with the turns ratio shown in the technical data sheet.
Equipment: Use a turns ratio tester or multimeter.
Steps:
First, similar to the second continuity test, use the resistance range of the multimeter to measure the resistance of the primary (high voltage) winding and the secondary (low voltage) winding. Then calculate the expected turns ratio of the winding based on the rated voltage and compare the measured value with the expected turns ratio to get the result: Check whether the turns ratio of the power transformer is qualified.
4. Core Grounding Check
Purpose: To ensure that the core is properly grounded.
Steps:
Check the ground connection of the transformer.
In this inspection test, we want to ensure that the core of the transformer is properly grounded to prevent leakage and danger to personnel.
5. Visual Inspection
Purpose: Observe the appearance of the power transformer for any signs of physical damage or whether the equipment is overheating.
Steps:
Inspect the power transformer's housing, accessories, oil tank, oil pillow and other parts for any visible signs of damage, such as cracks, corrosion or burnt areas.
Inspect the transformer for wear or loose connections.
Of course, the power transformer test items include but are not limited to the above tests, such as no-load tests and other power-on tests. If you are not convenient to perform other tests, Yawei Transformer Company can also provide various testing services for transformers below 550 kV. Welcome to consult!
FAQ
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A: Always a pre-production sample before mass production; Always final Inspection before shipment;
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