I. Overview
MOA-30kV Zinc Oxide Surge Arrester DetectorIt is specifically used to detect internal defects of poor electrical contact between MOA valves in gapless zinc oxide surge arresters for 10kV and below power systems, measuring the DC reference voltage (U1mA) of MOA and leakage current at 0.75 U1mA. This instrument integrates a DC high-voltage power supply, measurement and control system, and all components are concentrated in one chassis. It has the characteristics of small size and light weight, and is an equipment for on-site testing of power systems and zinc oxide lightning arrester production plants.

2、 Technical parameters of zinc oxide lightning arrester detector
1. Measurement range: Voltage 0-30kV Current: 0-1000 μ A
2. Measurement accuracy: Voltage 1%
3. Environmental temperature: 0~+40 ℃
4. Relative humidity: ≤ 85% at 25 ℃
5. Altitude: ＜ 1000M
6. Power supply voltage: 220V ± 10%
7. Power frequency: 50 ± 1HZ

3、 Usage method of zinc oxide lightning arrester detector
1. Open the instrument box cover and firmly ground the instrument casing.
2. Insert one end of the lightning arrester into the high-voltage sleeve of the instrument (H end), and clamp the other end with a wire clamp. Alternatively, an insulated wire can be used to lead out the external test sample from the high voltage end.
3. After turning on the power switch and conducting an internal self check of the instrument, the alarm light and discharge light will turn on, and the two meter heads will indicate a value of zero ± 1 word.
4. Press the reset button once, the alarm light will turn off, and the instrument will enter the detection state for testing.
5. After pressing the detection button for about 1 second, release it and the instrument will automatically complete all the detection items of MOA.
6. Precautions
(1) If the detection button is pressed and the alarm light is on, it indicates that there is a poor contact defect inside the MOA or that the external wiring is not secure. After the discharge lamp lights up, check whether there is a problem with the external wiring, or replace the test sample and press the reset button again to perform the next detection.
(2) If the alarm light does not light up, it indicates that the internal contact of MOA is good and there is no problem with the wiring. The instrument will automatically enter the state of measuring U1mA and Id, and display the test results on the meter head. After the discharge light lights up, the test is completed, and the test wiring is removed or the test sample is replaced for the next test.

4Zinc oxide lightning arrester detectorDebugging and troubleshooting
1. Zero adjustment of instrument head
After using the instrument for a period of time, it may need to be adjusted. Remove the instrument movement from the box, start the instrument, and the alarm light will turn on (do not connect the test sample at this time). Press and hold the detection button, adjust the corresponding potentiometer on the circuit board (see the schematic diagram of the main component positions on the circuit board), until the meter head indicates "zero ± 1" for voltage and current zeroing respectively.
2. Calibration of 0.75U1mA
Set the calibration button to 0.75U1mA, connect the test sample, press the detection button, read the voltage value of U1mA, release the detection button, and the instrument voltage will immediately change to another voltage value U1, which is 0.75U1mA. Compare the two for calibration. If U1=0.75U1mA, no adjustment is required; U1≠0.75U1mA， Make appropriate adjustments by adjusting the corresponding potentiometer on the circuit board until U1=0.75U1mA. After instrument calibration, it can ensure measurement accuracy for a considerable period of time without frequent adjustments. Calibration completed, set the calibration button to U1mA state.
3. Instrument error adjustment
After using the instrument for a period of time, if any errors are found, adjustments can be made. After connecting the test sample, if the U1mA value is determined, assuming it is 27.0kV, hold down the detection button and check whether the indicated value on the voltmeter is equal to the reference voltage U1mA (27.0kV) of the tester. If not, adjust the potentiometer on the left side of the voltmeter head. After adjustment, release the detection button. (See Figure 1 below, adjustment of reference voltage)
4. Handling of Simple Malfunctions
If the ammeter head displays "[[[]" or the sum reaches zero, it indicates that the input protection level operational amplifier (CA3140E) IC1 of the current circuit is equivalent to a damaged fuse, and the configured components should be replaced.