Portable Partial Discharge Detector

HMJFD-3A Portable Partial Discharge Detector

HMJFD-3A Portable partial discharge detector is a new type of digital partial discharge detector developed by our company. It retains the advantages of HMJFD-3A partial discharge detector, reduces the volume and optimizes the performance. It uses 10.1 inch touch screen to replace the traditional operation mode of oscillograph and physical knob, making it more convenient to use.

The instrument adopts full touch screen operation, which not only improves the service life of the operation, but also has the following functions: one key automatic correction; high voltage test voltage divider ratio can be set; serial communication upload test data. The instrument has the characteristics of high sensitivity, wide application range, wide dynamic range of amplification system, multiple frequency bａnd combinations (nine kinds), and strong anti-interference ability. It is a practical partial discharge testing instrument widely used by electric power departments, manufacturers and scientific research institutes.

1. The equivalent capacitance ranges from 6pF to 250 μ F

2. Number of channels: single channel

3. Measurement range: 0.1pc-10000nc

4. Detection sensitivity and allowable current (see Table 1)

Table 1. Detection sensitivity and allowable current value of input unit

5. Elliptic scan time base

(1) Frequency 50/60, 100, 150, 200, 400Hz

(2) Rotation: 30 ° as the first gear, and can rotate 120 °

(3) Working method: ellipse sine wave straight line

6. Display unit

10.1 inch capacitive touch screen is used.

7. Amplifier

(1) 3dB low frequency fl:10, 20, 40KHz optional

(2) 3dB high frequency fh:80, 200, 300kHz optional

(3) Gain adjustment, rough adjustment 6, inter gear gain difference 20 ± 1dB, fine adjustment range >20db

(4) Asymmetry of positive and negative pulse response ＜ 1dB

8. Time window

(1) Window width: adjustable, 5 ° ~ 170 ° at 50Hz

(2) Window position: each window can rotate 0 ° ~ 170 °

(3) Two time windows can be opened separately or simultaneously.

9. Peak pulse display

The touch screen displays 1 decimal place (10pc or more), 2 decimal places (less than 10pc), error: ± 3% (in full scale)

10. Test voltage display

(1) Range 150kV

(2) Input impedance: >1m Ω

(3) Display: touch screen display, display 1 decimal place

(4) Error: ± 1%

11. Test frequency display

Error: less than ± 1%

12. Zero standard system

Zero sign is consistent with all ellipse scanning frequencies

13. Structure

(1) Dimensions: 370mm (width), 460mm (depth), 215mm (height)

(2) Weight: about 12.5kg

When the sample CX produces partial discharge under the test voltage, the pulse current is generated through the coupling capacitor Ck, and the pulse signal is picked up by the input unit. After being amplified by low noise preamplifier, filter amplifier and main amplifier (reaching the required amplitude), the visible discharge pulse is generated on the elliptical scanning baseline of the touch screen, and the pulse peak value is displayed at the same time. The time window unit selects the working time of the pulse peak meter in each cycle of the test voltage, and marks the corresponding display area of the touch screen in red during this working time, which can avoid the interference of fixed phase, which is a conventional discharge test method.

When using JZF calibration pulse generator to inject the known electric quantity of sample CX, through automatic correction, the display value of discharge capacity is consistent with the injected electric quantity, so the discharge quantity of the tested object can be read out directly on the touch screen during the voltage test without calculation, which is very convenient.

The instrument is a desktop standard cabinet structure. The operation surface of the instrument is divided into two parts: front panel and back panel. The positions of each component are shown in Fig. 2a and 2b

Figure 2a HMJFD-3A Schematic diagram of front panel of Portable partial discharge detector

Figure 2b HMJFD-3A Schematic diagram of back panel of Portable partial discharge detector

Description Of Front Panel And Rear Panel Components

1. Touch screen: display the measured PD waveform, PD, test voltage, test frequency and other parameters;

2. Power switch button: press once to turn on; press again to turn off;

3. Partial discharge input: partial discharge measurement signal input,HMJFD-3A single channel, signal can be connected from any channel;

4. High voltage voltage divider, voltage range: 150V;

5. Grounding bolt: reliable grounding is required during test;

6. RS232 port: through this serial port, the parameters of partial discharge instrument can be uploaded to other equipment;

7. External power supply input;