2024-12-27

Application and Purpose Analysis of Grounding Transformers

The Necessity of Grounding Transformers In power systems, proper grounding of various components is of great significance. It can significantly improve the availability, basic insulation level, overvoltage withstand capability and short-circuit withstand capability of components. However, some system parts may lack the neutral connection required for grounding. In such cases, auxiliary components like grounding transformers are needed to achieve the grounding function.   Grounding transformers create grounded neutral connections for ungrounded three-phase systems, such as delta-connected and ungrounded star-connected systems. When a single-phase ground fault occurs in such isolated or ungrounded three-phase systems, since there is no grounding path, the zero-sequence fault current will not be able to return. At this time, although the system can still continue to operate, the fault will cause the voltage of the unfaulted lines to increase by a factor of √3 (1.73), which will subject the insulation of transformers and other components of the system to 173% overstress. Moreover, although solid-state devices such as metal oxide varistors (MOVs) are often used to suppress voltage spikes, under fault conditions, even without sufficient flashover voltage, the thermal effect generated by the leakage current may damage these devices.   Obviously, if the system lacks sufficient fault tolerance,...

2024-12-27

How to Distinguish between Power Transformers and Distribution Transformers

In the field of electricity, power transformers and distribution transformers are two important components that play different roles in the power system. To clearly understand the differences between them, let’s first get to know the definitions, application ranges, and working principles of these two types of transformers. Definition and Characteristics of Power Transformers Power transformers are mainly used to change the voltage and current characteristics of power signals, thereby ensuring that electricity can be smoothly transmitted in circuits with different power requirements and ratings. Like other transformers, it belongs to static electrical machines because there are no moving parts inside (although tap changers and protective valves will operate under certain circumstances, but not during the stable operation of the transformer). Power transformers can be used as step-up or step-down transformers according to actual needs to adjust the voltage and current levels of electrical signals. Its working principle is based on mutual induction, and during the voltage and current conversion process, the power and frequency on both sides of the transformer remain unchanged, which means that equivalent power transmission can be achieved between circuits with different voltage and current levels.   In practical applications, power transformers are usually installed in power...

2024-11-22

Conductors for Low Voltage Dry Type Transformers: Aluminum vs. Copper

Low voltage dry type transformers can have windings made of either copper or aluminum. They have a primary winding to get power from the source and a secondary winding to supply power to the load. These windings, made of insulated conductive wires, function the same regardless of the material.   Regional Differences in Application In North America, transformers of 15 kVA or higher usually use aluminum for windings. In most other parts of the world, copper is more common. There are two main reasons for choosing aluminum. First, it has a lower initial cost. Copper’s price has fluctuated a lot more historically, making it more expensive to buy. Second, aluminum is very ductile and easier to weld into windings, cutting manufacturing costs. But copper is more reliable for connections, while the reliability of aluminum connections depends on the installer’s skill.   Comparison of Material Properties (1) Coefficient of Expansion When heated to the same temperature, aluminum expands nearly one-third more than copper. If bolted connections aren’t done right, this can cause problems like loose joints. To fix this, we can use spring-loaded connections and special washers for aluminum windings. With the right hardware, aluminum joints can be as good as copper ones....

2024-11-22

Key Points for Transformer Selection

Transformers transfer electrical energy between circuits and are used differently in various industries, mainly for adjusting voltage. For example, they can step down voltage for low-voltage equipment or step up voltage for long-distance power transmission.   When buying a transformer, it’s important to consider carefully and check its specifications for optimal and efficient functions. Here are key factors for selection: Phase Number Before choosing a transformer type, determine the equipment’s application and type. Single-phase transformers are common in household appliances, while three-phase ones are for large enterprises with heavy loads. Manufacturers list compatible phase numbers and equipment types in manuals, which you should refer to for a proper match.   Operating Environment The operating environment matters a lot in transformer selection. Its parameters should fit the environment for stable operation. In open areas exposed to weather, liquid-filled or oil-cooled transformers are better as they protect windings from weather risks like humidity and temperature changes. For dry-type transformers in harsh environments like salty air and high temperatures, anti-corrosion paint coatings are needed to ensure stability and a long service life.   Power Characteristics and Protection Ideally (ignoring losses), the KVA on the primary and secondary sides of a transformer is equal....

2024-09-29

Scott Transformer: Principle, Advantages, and Applications

Principle: The Scott transformer, also known as the Scott-T transformer, is a special transformer design used to convert single-phase power to two-phase power or two-phase power to three-phase power. In a Scott transformer, two single-phase transformers are connected together, with one set of windings referred to as the primary winding and the other as the auxiliary winding. The phase difference between the primary and auxiliary windings is 90 degrees. By properly designing the turns ratio and phase relationship of the transformer, the Scott transformer can effectively convert two-phase power into three-phase power. Advantages: Phase Conversion Capability: The Scott transformer efficiently converts two-phase power to three-phase power, increasing the flexibility and versatility of the power system. Simplicity and Reliability: Its relatively simple structure ensures reliable operation and ease of installation and maintenance. Cost-Effective: Compared to other phase conversion devices, the Scott transformer is a more economical solution. Versatility: Suitable for a wide range of applications, including power systems, distribution networks, and laboratory environments. Disadvantages: Power Limitation: The power conversion capability of the Scott transformer is limited, making it unsuitable for high-power applications. Space Requirements: Additional space is needed to accommodate two transformers, which may be a constraint in space-limited environments. Phase...

2024-09-29

Electric furnace transformer: principles, advantages and applications

Principle: An electric furnace transformer is a specialized transformer used for electric furnaces. Its working principle is similar to that of a standard transformer. The main function of the electric furnace transformer is to step down the high voltage from the main power supply to the low voltage required by the heating elements of the furnace. Electric furnace transformers typically have a high current capacity to meet the furnace’s high power demands and are equipped with an appropriate insulation system to ensure safe and reliable operation. Advantages: High Efficiency: Electric furnace transformers are highly efficient, effectively converting high voltage to the required low voltage, thus reducing energy consumption. Precise Control: These transformers have precise voltage control capabilities, providing stable voltage output based on the heating requirements of the furnace. High Reliability: Professionally designed and manufactured, electric furnace transformers are highly reliable and durable, capable of long-term stable operation. Versatility: Electric furnace transformers are suitable for various types of furnaces, including induction furnaces, arc furnaces, and resistance furnaces, making them widely applicable. High Safety: Equipped with multiple safety protection devices, electric furnace transformers effectively prevent electrical faults such as overload and short circuits, ensuring the safety of both equipment and personnel....