High Potential Test Equipment / High Voltage Insulation Tester For The End Of Stator

Generator Surface Potential Tester , Insulation Tester For The End Of Stator , Potential External Displacement Method

I.Product Introduction and Why use the tester :

FBG-II generator surface potential tester is an insulation tester with rod type for detecting generator stator end insulation defects by surface potential method (also called potential external displacement method). By detecting the tightness and relative insulation strength of the stator end . It can goodly find the  end insulation of the stator caused from the artificial wrapping&packing and welding poorly , which not be found by the AC and DC withstand voltage test to the generator stator winding.

The surface potential measurement of the generator stator coil end is a new test item, and plays a insulation supervisory role through checking the end insulation, further improving the reliability of the safe working of the generator.

II. Main paramter of the tester :

1. Input resistance 100MΩ

2. Test voltage: DC 0-30KV

3. Voltage accuracy: 1.0%

4. Battery : 6F22 9V

III. Structure And indication of tester

1, handle             2, battery                   3, grounding column
4, the head          5, lengthened tube    6, voltage divider part
7, rod probe        8, power switch button

Note: The lengthened tubes have three pieces , so the operator can lengthen the detecting distance according to the actual field.

IV. Test  principle and using method

1 Test standard: The insulation DC test voltage of the stator coil end of the generator is 2 times the rated voltage, and the leakage

                           current is not more than 1 microamperes.

2. Test instrument: ZGF-60KV/2mA  DC high voltage hipot tester   1set

                              FBG-II  generator surface potential tester         1set

                              HV shielding microamperes

3. The test principle:

The DC voltage is applied to the stator bar through ZGF-60KV/2mA DC high voltage hipot tester, the volume resistance Pρ of the bar insulation is much larger than the surface resistance ρσ, and the ground voltage is very low. If a wire bar has defects, its voltage distribution will change significantly. When there is a defect in the insulation, Ρρ decreases, and the insulation voltage drop also decreases, causing the voltage at the defect site to increase. so the FBG-II tester can capture the voltage changing data , then judge whether there has defects.

4.The test method :

Firstly short-circuit the three-phase lead-out wire of the winding with the stator, the DC high-voltage generator injects  2 times voltage to the winding, and the voltage and current are tested by the generator potential external shift tester(FBG-II). 

Note :The ground wire of the (FBG-II) test rod must be connected to the ground wire of the high voltage generating device.

5. Precautions:

5.1. When the foil insulation paper is wrapped at the end of the stator, it must be wrapped tightly, otherwise betwwen the foil paper and the insulating surface of stator will form a capacitor. When the measuring rod of FBG-II is in contact with the winding of stator, there is a large discharge current, which causes misjudgment and influence on the test value.

5.2. When the end is wrapped, it should be divided into the line rod side and the water inlet side, and the interval of the both sides is greater than 3 cm. so that to find out  the defects problem is from one side , in fact, the main defects point  is at the root and the cone of stator, the measurement of the middle part has no significant.

5.3, The micro-ampere meter connected with the measuring rod of FBG-II tester should be digital type,  reading and protected will be easily

5.4, The end joint is in the lower part of the stator casing, it is not easy to measure, please  lead out in advance before testing.

5.5, It is important to remark the abnormal slot number and avoid mistaken.

5.6. Firstly blow off cooling water completely in the stator before the above testing.