High voltage test transformer

1High voltage test transformerTechnical Requirements:

1. Environmental requirements for the use of test transformers:
1.1 Input voltage: AC 220V 50Hz;
1.2 Environmental temperature: -40 ℃ to 40 ℃;
1.3 Relative humidity: ≤85% (at an ambient temperature of 25 ℃);
1.4 In an environment free from chemical gases and vapors;
1.5 In non explosive gases;
1.6 In situations where rainwater does not infiltrate.

2. Technical parameters:

Note:

1. Our factory's test transformer can achieve AC communication for a single unit300kV,capacity300kVA；
2. If the user needs, the test transformer produced by our factory can be extracted200VThe cascade tap can cascade two or three units into AC100kVThe150kVThe200kVThe300kVThe high voltage. It can also be extracted from the high-voltage winding according to the user's needs5～15kVThe medium voltage tap is used for AC withstand voltage testing of high-voltage motors;
3. in the table'DC high voltage output'One column shows the DC high voltage output value of the dual-purpose test transformer for both AC and DC;
4. Our factory can also customize various special specifications of test transformers according to user requirements.

IIHigh voltage test transformerOperation steps:

1Connect the leads according to the wiring schematic and reliably ground the transformer and control box;

2Before the experiment, check whether the wiring of each part is in good contact and whether the voltage regulator of the control box is adjusted'zero'Position;
3Connect the power supply, the green indicator light will turn on. Press the start button, and the red indicator light will turn on, indicating that the transformer has been powered on and is waiting for voltage to increase;
4Rotate the regulator handle clockwise at a constant speed to increase the pressure, and pay close attention to the instrument indication and the condition of the test sample;
5After the experiment is completed, the voltage should be quickly reduced to zero and the stop button should be pressed, then the power should be cut off and the test lead should be disconnected.

3、 Attention:

1. When conducting high-voltage tests, two people or2More than one person shall participate, and clear division of labor and communication methods between each other shall be established. And there is a dedicated person to monitor on-site safety and observe the test status of the test samples;
2Transformers and control boxes should have reliable grounding;
3During the experiment, the boosting speed should not be too fast, and sudden full voltage power on or off is not allowed;
4If any abnormal conditions are found during the boost or withstand voltage test, the voltage should be immediately reduced, the power should be cut off, the test should be stopped, and the cause should be identified before conducting the test.①The pointer of the voltmeter swings greatly;②Discovering the odor and smoking phenomenon of burnt insulation; ③ There is abnormal sound inside the tested object.
5In the experiment, if the test sample is short circuited or breaks down due to a fault, the overcurrent relay in the control box will work. At this time, the voltage regulator should be returned to zero and the power should be cut off before the test sample can be removed.
6. When conducting capacitance tests or DC high-voltage leakage tests, after the test is completed, the voltage regulator should be lowered to zero and the power should be cut off. Then, a discharge rod should be used to discharge the high voltage end of the test sample or capacitor to the ground to avoid the risk of electric shock caused by the potential remaining in the capacitor.

4Capacity selection of test transformer:

Nominal test transformer capacityPnThe formula for determining:
Pn=kVn²WCt10^-9
Where:Pn-Nominal test transformer capacity（kVA）；
k -Safety factor;
Vn-The effective value of the rated output high voltage of the test transformer（kV）；
W -Angular frequency,W=2πf,fTo test the frequency of the power supply;
Ct-The capacitance of the test sample（PF）.
For different test voltagesVnChoose an appropriate safety factorkWhen the nominal test voltage is low,kThe value can be higher; The following lists different test voltagesVnThe selected safety factorkValue, for reference:

Vn=50～100kV k=4；
Vn=150～300kV k=3；
Vn≥300kV k=2；
Vn≥1MV k=1.
The capacitance of the tested equipmentCtIt can be measured by an AC bridge.CtThe changes are significant and should be determined by the type of equipment. The typical data is as follows:
Rod shaped or suspended insulator Several tens of microfarads;
voltage transformer 200～500PF；
Graded casing 100～1000PF；
Power Transformer ＜1,000 kVA, I'm sorry, I'm sorry.～1000PF；
Power Transformer1,000 kVA, I'm going to go in and I'll go in 1000～10000PF；
High voltage power cables and oil immersed paper insulation 250～300PF/m；
Gas insulation ～60PF/m；
Closed substation,SF6Gas insulation 100～10000PF.