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High-voltage test transformers are essential testing equipment used by power plants, power supply bureaus, and scientific research institutions for AC withstand voltage tests. They meet the standards of the National Quality Supervision Bureau and are used for insulation strength tests at specified voltages on various electrical products, components, and insulating materials, assessing the insulation level of products, detecting insulation defects in test objects, and measuring overvoltage capability.
- Chinese Name
- Light High-Voltage Test Transformer
- Rated Capacity
- 1～300KVA
- Transformation Ratio Error
- ≤±1.5%
- Impedance Voltage
- <10%
Table of Contents
Test transformers are divided into three types by medium
YD Oil-immersed test transformer: Large capacity, low cost, easy maintenance, mainstream product.
YDQ Gas-filled test transformer: Good arc extinguishing performance, light weight.
GTB Dry-type test transformer: Light weight, small volume, can be placed upside down, expensive.
YD(C) Cascade high-voltage test transformer: Small capacity, low voltage, light weight, easy to transport and install.
YD Oil-immersed High-Voltage Test Transformer
This series of products features a single-phase core type iron core, laminated with high-quality cold-rolled grain-oriented silicon steel sheets, and fastened with steel clamps. The high-voltage coil is a cylindrical multi-layer tower type, wound with high-quality polyester enameled wire and high withstand voltage insulating materials. The low-voltage coil is on the outside, and the instrument coil is an independent winding, typically 100V. The shell is octagonal, and test transformers above 10KVA are equipped with movable iron wheels. It has the characteristics of light weight, small size, easy movement, and superior performance.
Oil-immersed AC/DC Test Transformer
Working Principle
1. AC, AC/DC test transformer:
Input the power frequency power supply into the operation box (or console), adjust the voltage through the auto-transformer and input it to the primary winding of the test transformer. According to the principle of electromagnetic induction, power frequency high voltage can be obtained at the secondary (high-voltage) winding. This power frequency high voltage can be rectified by a high-voltage silicon stack and filtered by a capacitor to obtain DC high voltage, whose amplitude is 1.4 times the effective value of the power frequency high voltage. However, when using DC, the short-circuit rod should be pulled out; when using AC, the short-circuit rod should be inserted.
2. Test transformer with taps:
To simultaneously satisfy the contradiction between higher voltage with lower current and lower voltage with higher current, the high-voltage winding is divided into two windings: one with a larger current and the other with a smaller current. The two windings are then connected in series and led out separately. Schematic diagram.
3. Cascade test transformer:
To obtain a higher voltage test transformer, a cascade method can also be used to achieve higher voltage. Figure 2 shows the principle wiring diagram of a three-stage cascade test transformer. The capacity and voltage relationships of the three transformers satisfy: P1=2P2=3P3, U(total)=1U+2U+3U.
Main Technical Indicators
>Rated capacity: 1～300KVA
>Single unit rated output voltage:
(AC) 50, 100, 150, 200, 300KV
(DC) 70, 140, 210, 280KV
>Rated input voltage: 200V, 400V
>Transformation ratio: 500/1, 1000/1, 1500/1, 2000/1, 3000/1
>Transformation ratio error: ≤±1.5%
>Impedance voltage: <10%
YDQ Gas-filled Test Transformer
Gas-filled test transformer
With the development of China's power industry, the voltage level requirements for test transformers are getting higher and higher, while traditional oil-immersed test transformers are increasingly unable to meet the requirements of on-site work in terms of volume and weight. Gas-filled test transformers reduce volume and weight, making it more convenient for customers to carry to the site for testing
With the progress of basic scientific research in China and the application of new materials and processes, the new medium sulfur hexafluoride gas has been introduced into the application field of power equipment. Due to the excellent insulation and arc extinguishing performance of sulfur hexafluoride gas, as well as its non-flammability, it has been widely used as a new insulating medium.
Structure
1. The design concept, material selection, and process flow of the YDQ series products are all new. Therefore, not only are they small in size, light in weight, and beautiful in appearance, but all technical indicators also meet the requirements of the <
The YDQ series products use high-quality cold-rolled DQ-151 oriented silicon steel sheets laminated into a multi-stage cylindrical frame iron core, and use QZ type wires to continuously wind the high-voltage tower coil directly on a specially made high-strength insulating cylinder. The shell is of suitable size and filled with SF6 gas.
2. The difference between YDQ (JZ) products and YDQ products is that the high-voltage rectifier silicon stack is cleverly installed inside the high-voltage bushing. By inserting or pulling out the short-circuit rod, the YDQ can be switched between power frequency high-voltage AC output and high-voltage DC output.
3. The difference between YDQ (C) products and YDQ products lies in the internal structure of the bushing.
3. Main Features
>This product is small in size and light in weight (40%-65% lighter than oil-immersed test transformers of the same level).
>Clean, no oil stains, no maintenance required.
>Unaffected by harsh climate conditions, can be tested immediately after on-site handling without needing to rest.
>Insulation strength is significantly higher than oil-immersed test transformers, with minimal corona.
4. Technical Parameters
>Voltage level: 10——600KV
>Capacity range: 1——600KVA
>No-load current: <7%
>Impedance voltage: <8%
>Partial discharge at rated voltage: <5PC
GTB Dry-type Test Transformer
Overview
This series of products has the characteristics of light weight, small size, beautiful appearance, stable performance, and easy portability, especially suitable for on-site operation. It is a new type of AC/DC dual-purpose high-voltage test transformer for domestic upgrades. This series of products is suitable for on-site testing of insulation performance of various electrical equipment in power systems and various power users, as well as high-voltage power sources in various voltage systems or devices with DC high voltage and small current for electrical products.
Dry-type Test Transformer
Structure
This series of transformers uses advanced production equipment, adopts new processes of coil winding epoxy vacuum casting and CD-type iron core. Compared with similar oil-immersed transformers, it significantly reduces weight and volume, improves insulation strength and moisture resistance in quality, and effectively reduces magnetic flux leakage, greatly enhancing performance.
Technical Indicators
>Impedance voltage: 12%
>Output voltage waveform: power frequency, sine wave
>Surface temperature rise: <55℃
>No-load loss: 0.2%~0.35%
>Allowable continuous overrun time: 1/hour
>Intermittent operation time: continuous
YD (C) Cascade High-Voltage Test Transformer
