Product Details

Cascade High-Voltage Test Transformer Manufacturer

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The main features of the cascade high-voltage test transformer: the entire test device is composed of several single test transformers, each with small capacity, low voltage, and light weight, making it easy to transport and install.

Overview

The main operational characteristic of the cascade high-voltage test transformer is that it is composed of several single test transformers. Each single test transformer has the characteristics of low voltage, small capacity, and light weight, making it extremely easy to install and transport. This also gives the cascade high-voltage test transformer its own unique features. It can either be used in combination by connecting several single test transformers in series to achieve a voltage several times higher, or it can be directly separated into several sets of single test transformers for independent use. 

Basic Principle of Cascade Transformers

If the voltage of a single transformer exceeds 500kV, the cost of voltage will rise rapidly and increase, and it will have a great impact on the insulation performance of the mechanical structure. In addition, it will also cause difficulties in installation and transportation. Based on this situation, the rated power of a single transformer currently used in China generally does not exceed 750kV. Therefore, in specific applications, when voltage requirements above 500kV or 750kV are needed, it is achieved through transformer series connection. Usually, connecting several test transformers in series involves winding operations on several transformers to achieve voltage superposition, and then optimally simplifying the insulation structure of each single transformer as a whole. The autotransformer cascade transformer is the most common type of cascade transformer. 

Measures to Reduce the Short-Circuit Reactance of Test Transformers

In specific tests, in order to ensure that the test object does not have the problem of too small short-circuit current under flashover conditions, it is necessary to effectively reduce the short-circuit reactance of the test transformer to a certain extent. The voltage level of a single-high-ratio bushing test transformer is relatively low, so when reducing its short-circuit reactance, the low-voltage windings can be evenly wound on the left and right core rods, and then the two low-voltage windings can be connected in parallel to effectively strengthen the closure between the high and low voltage windings. The cascade operation of a double-high-voltage-bushing transformer is mainly to effectively save insulation, so that the secondary low-voltage winding and the secondary voltage winding are not mounted on the same core limb. If reasonable and effective methods and measures are not taken, the short-circuit reactance of the transformer will increase. In response to this situation, balancing windings can usually be wound on the two core limbs.

1. Number of turns

Assume that the number of turns of the balancing windings on the left and right limbs are NP₀ and NP₁ respectively, and the number of turns of the two is in the same state, and in specific operations, the number of turns generated during the winding process of the primary low-voltage winding is the same, assuming that the same number is N₀. Based on this, we can obtain NP₀=NP₁=N₀.

2. Connection

The balancing windings on the left and right limbs can be connected through the polarity terminals. If there is a problem of different winding directions in the balancing windings of the two limbs, it should be corrected to achieve normal head-to-head and tail-to-tail connection; but if the winding directions are consistent, head-to-tail connection can be achieved. To ensure overall standardization and reasonable effectiveness.

3. Current

Due to some operational reasons, a certain current may pass through the balancing windings. This is mainly because in the entire core circuit, the magnetomotive forces of the two windings are equal in magnitude but opposite in direction, which makes it difficult to generate magnetic flux in the entire core circuit.

4. Magnetic flux

When the magnetic flux linked by the balancing windings on the left and right sides is not equal, the electromotive forces induced by the two will be different in magnitude, and only under such basic conditions will current flow through.



Note: The above information and technical parameters are compiled and released by Yangzhou Darui Electric Co., Ltd.