1 Overview

1.1 This tap changer is suitable for dry-type on-load tap-changing power transformers with rated voltages of 20kV and below, rated at 5000kVA for Y-connected transformers and 8000kVA for D-connected transformers.

1.2 Environmental Conditions

1.2.1 Indoor installation and use.

1.2.2 Ambient temperature: Maximum +40°C, minimum -25°C.

1.2.3 Operating altitude: Not exceeding 1000 meters.

1.2.4 Relative air humidity: Not exceeding 90%.

1.2.5 Installation sites must be free from severe explosive or corrosive gases and conductive dust.

2 Main Technical Parameters of Tap Changer

3 Schematic Diagram of Tap Switch Operation

The 20KV central (straddle-type) on-load tap changer is a key voltage regulating device in medium-voltage distribution transformers and is widely used in urban power distribution, industrial enterprises and new energy access scenarios. It can safely adjust the tap points of the transformer under load, achieve precise voltage control, and enhance the stability of the power grid and the reliability of power supply. This article will provide a detailed introduction from aspects such as product overview, working principle, structural features, installation and commissioning, operation and maintenance, and application prospects, to help users fully understand the functional advantages and application value of the 20KV central (straddle type) on-load tap changer.

I. Product Overview

The 20KV middle (straddle type) on-load tap changer is a device that can adjust the tap points of a transformer while it is energized. It adopts a straddle-type design, ensuring smooth operation and avoiding the impact of voltage fluctuations during voltage regulation on the power grid and load.

The main functions include:

Voltage regulation

The tap points of the transformer can be adjusted according to the load and grid voltage fluctuations to achieve stable control of the output voltage.

System protection

It is equipped with an internal protection mechanism that responds promptly in case of overload, short circuit or abnormal working conditions, ensuring the safe operation of transformers and distribution lines.

Improve the quality of power supply

Effectively control voltage fluctuations, reduce the impact on terminal devices, and enhance the user's electricity usage experience.

Intelligent control

Supports remote monitoring and automated operation, achieving status monitoring, alarm and remote adjustment, and improving the efficiency of operation management.

Ii. Working Principle

The 20KV middle (straddle type) on-load tap changer achieves load regulation through mechanical and electrical linkage. Its core principle is as follows:

Straddle tap design

The tap changer is connected across the main winding to ensure a smooth operation process, prevent voltage fluctuations during load regulation, and guarantee system safety.

Operation under load

It is equipped with an internal arc elimination mechanism, which can safely switch tap points under load conditions to prevent arc damage to equipment and the power grid.

Three-phase coordinated control

The three-phase transformer tap connection can be operated synchronously or independently to ensure the balance of three-phase voltage and improve the stability of the system.

Mechanical and electrical linkage

The drive mechanism controls the action of the tap changer, and at the same time, it realizes remote operation, status feedback and alarm functions through electrical signals.

Iii. Structural Features

The 20KV middle (straddle-type) on-load tap changer demonstrates high reliability and advanced nature in its structural design. Its main features are as follows:

Modular design

The drive mechanism and tap unit adopt a modular structure, which is convenient for installation, commissioning, maintenance and replacement, and is compatible with medium-voltage transformers of different capacities.

High-reliability contact system

The sub-contact points are made of wear-resistant and highly conductive materials to ensure reliable contact during long-term use and reduce resistance loss.

Straddling coil structure

The jumper design enables smooth switching during operation, avoiding tripping or instantaneous voltage surges.

Intelligent control interface

It can be connected to an automated system to achieve remote operation, status monitoring and alarm, thereby enhancing operational efficiency.

Protection and safety design

The casing is equipped with dust-proof, moisture-proof and anti-misoperation functions, adapting to various complex environments and ensuring the safe operation of the equipment.

Iv. Installation and Commissioning

Installation and commissioning are crucial steps to ensure the normal operation of the 20KV central (straddle-type) on-load tap changer. The main steps are as follows:

Selection of installation location

Installed in the middle of the transformer or at the tap position specified in the design;

Ensure that the operating mechanism is easy to maintain and leaves sufficient space for heat dissipation.

Mechanical installation

The drive mechanism is accurately and reliably connected to the tap changer, ensuring sensitive and precise operation.

Adjust the interlocking mechanism and check whether the mechanical operation is smooth.

Electrical wiring

Complete the wiring of the control power supply, status indication and protection circuit in accordance with the design drawings.

Check whether the wiring is firm to avoid loosening or short circuit.

Debugging and testing

No-load test: Operate the tap changer under no-load conditions to check the smoothness of the action and the accuracy of the indication.

Load test: Gradually increase the load to test the voltage regulation effect and system stability, and confirm the voltage regulation accuracy.

V. Operation and Maintenance

To ensure the long-term stable operation of the 20KV middle (straddle-type) on-load tap changer, regular inspection and maintenance are required

Inspection of mechanical components

Regularly check whether the tap changer, contacts and drive mechanism are worn or loose.

Replace worn parts when necessary to keep the operation sensitive and reliable.

Contact status monitoring

Use a contact resistance tester to measure the contact resistance to ensure good contact.

Regularly clean the contacts to prevent dust and oxidation from affecting the contact performance.

Maintenance of the control system

Check whether the controller, motor drive and signal lines are normal.

Update the control software or parameter Settings to maintain the stability of the automation functions.

Operation record and analysis

Record the number of tap operations, load conditions and voltage regulation effects each time to analyze the equipment lifespan and maintenance cycle.

Vi. Application Prospects

The 20KV central (straddle-type) on-load tap changer is widely used in medium-voltage distribution systems and holds significant value:

Urban distribution network

It is applicable to urban distribution networks, industrial parks and enterprise power grids, achieving voltage stability and enhancing power supply reliability.

Construction of smart grid

It can be combined with an automated system to achieve remote tap distribution operation and status monitoring, thereby enhancing the intelligence level of the power grid.

New energy access

In scenarios where distributed energy sources such as photovoltaic and wind power are connected, the voltage can be quickly adjusted to ensure the stable operation of the power grid.

Key power consumption sites

It is applicable to the power supply systems of hospitals, communication base stations and important industrial equipment, ensuring continuous and high-quality power supply.

The 20KV central (straddle type) on-load tap changer plays a key role in modern medium-voltage distribution systems due to its load regulation capability, straddle design and high reliability. Through scientific installation, commissioning and regular maintenance, tap changers can enhance the voltage regulation efficiency of transformers, ensure the stability of system voltage, extend the service life of equipment, and meet the modern power grid's demand for high-quality electricity. With the rapid development of smart grid construction and new energy, its application scope and market prospects will further expand.