HYG-3kVA/50kV light high voltage test transformer

HYG-3kVA/50kV light high-voltage test transformer is produced after extensive improvement on the basis of the original similar products according to the "Test Transformer" standard of the Ministry of Electrical and Mechanical Services. HYG-3kVA/50kV light high voltage test transformer is a new type of product which is improved on the basis of TDM (G) series test transformer according to the national standard "ZBK-41006-89". This series of products has the characteristics of small size, light weight, compact structure, complete functions, versatility and ease of use. It is especially suitable for power system, industrial and mining enterprises, scientific research departments, etc. to test the insulation strength of various high-voltage electrical equipment, electrical components and insulating materials under power frequency or DC high voltage. It is an indispensable equipment in high pressure testing.

HYG-3kVA/50kV control box

This series of control box is composed of contact type voltage regulator (electric pole type regulator of 50kVA or more) and its control, protection, measurement and signal circuits. It is to adjust the voltage regulator (that is, the input voltage of the test transformer) by connecting 220V or 380V power frequency power supply to obtain the required test high voltage voltage value.

Test transformer capacity selection

The formula for determining the nominal test transformer capacity Pn: Pn=kVn 2ωCt×10-9

Where: Pn - nominal test transformer capacity (kVA)

     Vn - the effective value (kV) of the rated output high voltage of the test transformer

k - safety factor. K≥1, when the nominal voltage Vn≥1MV, k=2; when the nominal voltage is low, the k value can be higher.

Ct——the capacitance (pF) of the test item

ω - angular frequency, ω = 2πf, f - frequency of the test power supply

The capacitance Ct of the device under test can be measured by an AC bridge. Ct varies greatly, depending on the type of device. Typical data is as follows:

Simple rod or suspension insulator

Simple grading sleeve 100~1000pF

Voltage transformer 200 ~ 500pF

Power transformer < 1000kVA ~1000pF

            〉1000kVA 1000~10000pF

High-voltage power cable and oil-impregnated paper insulation 250~300pF/m

Gas insulation ~60pF/m

Closed substation, SF6 gas insulation 100~10000pF

For different test voltages Vn, a different (appropriate) safety factor k is chosen. The k values selected for different Vn are listed below for reference.

Vn = 50~100kV k = 4

Vn = 150~300kV k = 3

Vn 〉300kV k = 2

Technical parameters, specifications and selection of control box

The capacity of the control box is nominally related to the capacity of the voltage regulator and the voltage regulator. If it is matched with the test transformer (working within 30 minutes), it can be based on the power industry standard of the People's Republic of China "DL474.4-92". "The rule: P0 = 0.75P optional. In the formula P0 - test transformer capacity; P - regulator capacity. If used in electrical professional factory products for batch testing, the regulator capacity should be equal to the test transformer capacity, ie: P0 = P.

The technical parameters of the control box are as follows
 

HYG-3kVA/50kV light high-voltage test transformer adopts single-frame core structure. The primary winding is placed on the core and the high voltage winding is external. This coaxial arrangement reduces the leakage flux and thus increases the coupling between the windings. The outer shell of the product is made of a octagonal structure with a better core, and the overall shape is elegant. The external structure diagram is shown in Figure 1, and the internal structure diagram is shown in Figure 2.

Figure 1: Single HYG-3kVA/50kV test Figure 2: Internal structure of a single test transformer

  Schematic diagram of external structure of transformer
1—short bar D 2—equal pressure ball 3—high voltage bushing 4—transformer handle
5—Oil valve 6, 7—Sub-voltage input a, x 8, 9—Measurement terminals E, F 10—Transformer housing ground
11—high pressure tail X 12—high voltage output A 13—high voltage silicon reactor 14—transformer oil
15—iron core 16—low voltage winding 17—measuring winding 18—secondary high voltage winding

In the HYG-3kVA/50kV test transformer, a and x are low voltage input terminals, E and F are instrument measuring terminals, and A and X are high voltage outputs.
 
This series of control box (set) is designed and manufactured according to the unique use range of high voltage test transformer. Its functions are:

A, closing the sound and light alarm;

B, timing sound and light alarm;

C, electronic low-voltage current protection (box type);

D, direct reading of high voltage;

E, the pressure test time is freely set (digital display);

F, mobile structure (desktop).