| 1. | Due to the adoption of frequency conversion technology, accurate measurement can be ensured under strong electric field interference. |
| 2. | The instrument uses a Chinese menu operation, and the microcomputer automatically completes the entire measurement process. |
| 3、 | This instrument is also suitable for measuring the tgδ and capacitance of high-voltage electrical equipment in workshops, laboratories, and scientific research institutions; it has the advantages of convenience, simplicity, and accuracy for insulation oil loss testing. |
| 4、 | This instrument can measure high-voltage electrical equipment that is ungrounded or directly grounded using positive or reverse connection methods. It can also measure the tgδ of capacitive voltage transformers and the capacitances of main capacitors C1 and C2. |
| 5、 | The instrument is equipped with an internal high-voltage step-up transformer and incorporates safety protection measures such as zero-crossing closing and lightning protection. During the test, it outputs high voltages of different levels from 0.5kV to 10kV, making operation simple and safe. |
Test Instrument Parameters
1. High voltage output: 0.5 to 10kV, with each step increasing by 500V, totaling 20 steps
High voltage output cable can be dragged on the ground for use
Three frequencies: 45Hz, 50Hz, 55Hz
2. Capacity: 1500VA
3. Accuracy: tgδ: ±(reading*1.0%+0.08%)
Cx: ±(reading*1.5%+5PF)
4. Resolution: tgδ: 0.01% Cx: 1pF
5. Measurement range: 0.1% < tgδ < 50%
3PF< Cx < 60000PF
At 10KV, Cx ≤30000PF
At 5KV, Cx ≤60000PF
6. Power supply: AC 220V ±10% 50 ±1Hz
7. Harmonic adaptation: ≤3%
8. Operating conditions: -15℃ to 50℃, relative humidity <80%
9. Dimensions: 460 (L) ×335 (W) ×340 (H)
10. Weight: 30 kg
Working principle:
After the variable frequency dielectric loss tester starts measurement, the high voltage set value is sent to the variable frequency power supply. The variable frequency power supply uses a PID algorithm to slowly adjust the output to the set value. The measurement circuit sends the actual high voltage to the variable frequency power supply, which fine-tunes the low voltage to achieve accurate high voltage output. According to the positive/reverse connection setting, the measurement circuit automatically selects the input and switches the range based on the test current. The measurement circuit uses Fourier transform to filter out interference, separates the fundamental wave of the signal, performs vector operations on the standard current and the test sample current, calculates the capacitance from the amplitude, and calculates tgδ from the phase difference. Multiple measurements are repeated, and a median result is selected after sorting. At the end of the measurement, the measurement circuit issues a voltage reduction command, and the variable frequency power supply slowly reduces the voltage to 0.
Precautions and Other Information
Precautions
1. This instrument can only be used on equipment that is de-energized; the grounding terminal should be reliably connected to the grounding grid,
The instrument should be used in a spacious, safe, and reliable place as much as possible.
2. The equipment under test should be disconnected from the high-voltage line from the operating state to the maintenance state, cleaned, and after a preliminary insulation test is satisfactory, the instrument can be used for testing to prevent damage to the instrument during voltage application due to poor insulation of the equipment under test.
3. Determine which connection method to use based on the installation situation of the equipment, and select the connection method in the corresponding menu option.
4. Correctly select the test voltage level according to different equipment, and select the required voltage in the corresponding menu option.
5. If a special situation endangering safety occurs during the test, the main power can be turned off urgently.
6. Only after turning off the power switch on the panel and clearly disconnecting the 220V test power supply can wiring changes be made or work be completed; when repeating a test on the same test equipment, you can press reset and then measure again, or choose to repeat after the previous test is completed.
7. To ensure measurement accuracy, especially when the loss of small capacitance test samples is small, it is necessary to ensure that the low-voltage end (or secondary end) of the equipment under test has good insulation and measure in an environment with relatively low relative humidity.
8. When conducting large capacitance test sample experiments, the grounding of the instrument and the grounding of the test sample should not be at the same grounding point to prevent the counter voltage or traveling wave from affecting the safety of the instrument during grounding discharge.
9. The instrument comes with a voltage boosting device; attention should be paid to the insulation distance of the high-voltage lead and personnel safety; 10. The instrument should be reliably grounded; poor grounding may cause machine protection or danger.
10. After the instrument is started, except for special circumstances, it is not allowed to suddenly turn off the power to avoid overvoltage damage to the equipment;
11. Although the special high-voltage wire (HVx) provided with the instrument has been tested and qualified at the factory, it should still be kept away from the human body and the low-voltage test line (Cx) during measurement; both the high-voltage core wire and the high-voltage shielding wire are not allowed to be grounded or connected to the low potential part of the test circuit.
The core wire and shielding wire of the CX input line are not allowed to contact the high-voltage part of the test circuit.
12. The instrument should be protected from moisture and severe vibration.
13. When the on-site interference is large and the power frequency cannot obtain definite results, the variable frequency measurement should be used; in other cases, the power frequency measurement should be used.
14. After issuing the measurement command, if the measurement result does not appear on the screen for a long time (1 minute), it may be caused by the test sample capacitance being too large or a system crash. Turn off the power and restart, then reduce the measurement voltage and measure again.
15. A short circuit in the test sample will prevent measurement, and the instrument will automatically protect itself. When a section of paper extends from the paper outlet above the machine head, press the button to stop paper feeding. The printing paper is allowed to be pulled outward.
