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....

2024-08-29

Common problems of dry-type transformers

Zero insulation resistance of the core to ground When the resistance is zero, it indicates a direct connection between metals (possibly due to burrs, metal wires, etc., carried into the core by the varnish, with both ends touching between the core and the clamp; base insulation damage causing a connection between the core and the base; or a metal object falling into the low-voltage coil, causing a connection between the pull plate and the core). Solution: Use lead wire to probe down the channel between the low-voltage coil and the core, and make sure there is no foreign object. Then check the base insulation. If the problem persists, the following method can be used: Connect the ground lead of a welding machine to the grounding plate, and tap the base with a welding rod (current about 250A); a single tap can solve the problem. Limit switch failure or abnormal operation The limit switch is a protective device for operators when the transformer is live. If the transformer is energized, the contacts of the limit switch should immediately close when any enclosure door is opened, triggering the alarm circuit and causing an alarm. Common faults when the temperature controller is running...

2024-07-30

Core Losses in Transformers

Any electrical equipment experiences losses over prolonged operation, and power transformers are no exception. 1.Definition and Principle Unlike copper losses, core losses in transformers are independent of the windings and current magnitude. Core losses, also known as “no-load losses,” are related to the transformer’s iron core and occur whether the transformer is under full load or no load. These losses are a fixed component of transformer losses. However, during operation, power loss decreases as the electric field intensity reduces.   2.Classification Core losses in transformers can be categorized into hysteresis losses and eddy current losses. Hysteresis Losses: The transformer’s operating principle is based on electromagnetic induction, facilitating voltage transformation and current variation. The magnetic flux flows through the iron core, which presents magnetic resistance to the flux, similar to how a conductor resists electric current. This resistance generates heat, resulting in losses known as “hysteresis losses.” Eddy Current Losses: When the primary winding of a transformer is energized, the magnetic flux it generates flows through the iron core. Since the iron core is also a conductor, an induced electromotive force (emf) is generated in the plane perpendicular to the magnetic lines. This emf forms a closed loop in the cross-section of the...