2. Capacitor
This type of voltage transformer is equipped with a capacitive potential divider connected between the main-line phase and ground. It combines a capacitive voltage divider with a magnetic transformer, making it a hybrid device. In the industry, these transformers are often referred to as intermediate converters with a relatively small transformation ratio.
Composed of a series stack of high-voltage capacitors, this type of transformer can be used both for voltage metering and for protection purposes. The capacitors first reduce the voltage level, after which a magnetic transformer further steps down the reduced voltage to a secondary voltage suitable for measurement and protection systems.
3. Optical
Optical voltage transformers are a relatively new type of transformer that can be used for safety and metering applications as an alternative to traditional electromagnetic converters. Their advantages have been widely discussed in scientific and technical literature, and their commercial applications have gradually gained recognition in the market.
However, many power plant operators tend to avoid using them due to their high cost and the relatively recent development of the technology. In many regions, there is still limited local technical expertise available, which often requires extensive cooperation or service agreements with manufacturers for operation and maintenance.
Although optical technology has demonstrated both advantages and disadvantages, research into improved optical solutions remains a major focus in advanced laboratories and continues to be an important direction for ongoing technological development.
Difference Between Voltage Transformer and Current Transformer
Definition
A voltage transformer is an electrical device used to convert a high voltage into a lower voltage value. The primary winding of the potential transformer is connected in parallel with the power line in order to measure the line voltage.
The transformer reduces the high voltage to a smaller, standardized level that can be safely measured using a voltmeter or other measuring instruments.
On the other hand, a current transformer is a device designed to convert a high current value into a lower, proportional current. It is commonly used in AC systems to measure large currents safely and accurately.
Since the current flowing in power systems can be very high and difficult to measure directly, a current transformer converts the large primary current into a smaller, proportional secondary current suitable for measurement and protection equipment.
Core
In both voltage transformers and outdoor low-voltage transformers, the type of core used can support operation at both high and low voltages. The core is made from high-quality materials and is designed to magnetize small currents efficiently at low flux density.
For current transformers, the core is typically constructed from laminated stainless steel sheets to handle high currents effectively. In contrast, the core of a voltage (potential) transformer is designed for high-performance operation at low current levels, allowing it to function efficiently in voltage measurement and protection applications.
Primary Winding
Voltage transformers generally have multiple turns in the primary winding, but the conductor used is relatively thin. For current transformers, the primary winding is usually a single thick turn, capable of carrying high currents without overheating.
Secondary Winding
In voltage transformers, the secondary winding uses a thinner conductor and has fewer turns, suitable for measurement devices. Current transformers, however, use a thinner conductor with multiple turns, capable of delivering standard secondary currents, typically in the range of 5A to 20A.
Applications
Voltage transformers, whether low-voltage or high-voltage, are primarily used for power supply monitoring, voltage measurement, and operating protective relays. Current transformers, on the other hand, are focused on current measurement, power monitoring, and providing safe, proportional current signals to protection and control equipment within the power grid.
Conclusion
Voltage transformers and current transformers are both equally essential in the generation, transmission, and distribution of electricity. Each type has its subcategories, such as low-voltage and high-voltage transformers, as well as specialized versions like constant voltage transformers and outdoor low-voltage transformers.
With ongoing technological advancements, innovative solutions—continue to enhance efficiency and reliability in the power industry. After all, even electricity deserves an upgrade!
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