Traditional coil testing machines are produced using SCR pulse generator, comparing the tested coil resonance waveform with the master waveform, and then judging it as good or bad coil according to the difference area of both waveform’s comparison. But we are convinced that the resonance waveform changing is not only from layer-short happened, so it is not correct completely to say < Waveform changing = Coil layer-short happened>
The view of full waveform comparison method means to compare all data that are inside the two coil waveforms, which data include 3 factors such as layer-short happened, pulse voltage instability and core permeability inconsistency. However, the core permeability is totally unrelated to the coil characteristics, so it is very hard to find out the layer-short coil with the waveform comparison method.
Almost all coil testing machines on the market has been using SCR circuit generating pulse waveform and the full waveform comparison method. Almost all manufacturers did not do their effort trying to analysis the complex coil waveform and trying to find out the real coil layer-short phenomenon, they just simply used the full waveform comparison method.
We have been doing much effort on the method of Power MOSFET circuit generating pulse waveform, after 20 years of hard work, finally it has been commercialized. The Power MOSFET pulse generator now can completely remove the disadvantages of SCR pulse generator and achieving a new method for testing coil.
The new coil layer short testing method is based on the method of Power MOSFET generating pulse wave, applying the pulse wave to the coil and turning off immediately, then the self-resonance wave will generate in the coil.
We measure the first peak wave value (A) and the second peak wave (B) from the self-resonance wave, then defining it as Quality data=B/A by "Q=**.*%" expression.
|SCR Pulse Generator||Power MOSFET Pulse Generator|
As described in Power MOSFET pulse waveform test, Q value comparison judgment method is not affected by applying voltage changes, and also not affected by core permeability, which are unrelated to coil layer short. This method can greatly improve the accuracy of judgment, at the same time it ruled out the shortcoming of big current that happened in SCR pulse generator method, so we do not need to worry again if the impulse test will damage the coil. The left waveform shows the smaller Q value caused from one turn layer shorted of coil by simulated.
Black waveform: Normal coil, Green waveform: one turn layer short simulation.
The reducing Q value of about 9.2% is enough to determine the motor coil is good or bad.
In the real test, we could set the effective Q value for detecting the bad coil, the effective Q value are from real testing on the coils sampling from producing line and layer short simulation data. Testing the motor coils, we do need to assess the factors of the air magnetic field and the core material uncertainty to confirm if it will affect the Q value measurement.
|Corona occurred between U-V coil
It can be seen clearly to determine Corona phenomenon occurred in the vicinity of 2.5kV. This method can be applied to determine quality assessment of motor coil at the stage of product development, can also be effectively used for quality control after mass producing.
Via USB interface, each individual test data can be stored on the PC, such as the following data table
|No||Vap kV||Vres kV||Qual %||Peri uS||Cor 1/0||Cor kV||NG Code|
In the column
For example with Corona high limit setting as 0.1kV, the test value will be 0.01,0.02, .......... 0.1kV.
Such test data for qualified products, the tested data relative to the Corona high limit are still very reliable security space gap, so it can be an effective quality control of the data.
|Green wave: Coil Self-resonance Wave
Yellow Wave: Corona gate time status and Corona measured data
The 6160 comes with a CD to install the software on the Windows PC as a waveform can be displayed on the left.
The attenuating shock wave of around 100Hz continuous sine wave
|6160HV+ Boosting transformer Becoming a Corona instrument|
|Green wave: Leakage and Corona Current
Yellow wave: Corona time gate status and Corona data
6160 can be used to assess the insulating properties of the insulating film of two electrodes, such as insulation properties owned small capacitance between the wires of cable, or between the coil and the core.
|Low Limit Control||Resonant Voltage (Current).................................□.□□||kV (A)|
|High/Low Limit Control||Quality (Q Value)................................................□□.□||%|
|Low Limit Control||Wave Period (Current)................................□□□□.□||uS|
|High Limit Control||Corona Quantity (Peak Voltage or A)................□.□□||kV (A)|
|Impulse Voltage||-0.1~-6.00kV/Variable setting by 0.01kV step High accuracy electronic servo-amplifier controller, no influence from power supply||±0.2kV or ±20% for small one|
|Output Current||100A Max.||-----|
|Pulse wave width||0.6~ 4uS by manual selection||Within ±20% of setting|
|Pulse output interval time||40mS fixing time||Within ±10%|
|Test speed||Pass or Fail result comes out in 50mS after start-command, then will have test result in 40mS for next test-command coming||-----|
|Output Voltage Measurement||0.00~9.99kV for Apply Voltage,
Resonant Voltage and low limit Voltage, Resolution: 0.01kV
|Quality Measurement (Q value)||0.00~99.9% setting for High/Low limit||within ±3% for tested wave data, the specimen is for 100H~100uH|
|Wave Period Measurement
|0.10~9999uS setting for Low limit||within (±0.1%±1digit) for tested wave data, the specimen is for 100H~100uH|
|Corona Quantity Measurement (Corona Voltage)||0.01~3kV(0-p) setting for High limit by 4Mhz,8Mhz Chebyshev approximation HPF||Calibrated by the experiment data of pseudo corona generator and the calculated data|
|Test conditions setting operation||Manual mode: All test conditions could be set by 3 manual keys and 4 arrow keys on panel. PC mode: Selecting the preset test conditions that copied from PC through SD card.|
|Test data saving method||1. Real time data saving in PC by USB I/F 2. Real time data saving in SD card|
|Corona graphic generation||The corona graph could be generated automatically from PC with Apply Voltage range and Corona data range setting|
|Wave Monitoring software||Shipping along the software that could monitor real time testing wave
(for Windows-XP and Windows-7)
|DC~20MHz with +1,-3dB, Voltage divider=1/1000|
|Power Supply||AC 90~240V, 50/60Hz||Within 70VA|
|Weight and Size||Machine Weight: 7.5kg, Accessories: 0.5kg (W)370mm/(H)150mm/(D)355mm, 410mm for Handle width||Accessories: HV Coaxial cable, Signal Coaxial cable, Power Cable and remoter|
|NOA CORPORATION Co., Ltd.|
4-31-9 Nakanokamicho, Hachioji-city, Tokyo, 192-0041, JAPAN
| Satake Asia Sales & Services Co., Ltd.|
No. 21, Lane 86, Wugong 3rd Rd, Xinzhuang Dist, New Taipei City (24889), Taiwan, R.O.C.