Tester Features
| 1. | Due to the adoption of frequency conversion technology, accurate measurement can be ensured under strong electric field interference. |
| 2. | The instrument is operated via a Chinese menu, 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 is especially convenient, simple, and accurate for loss testing of insulating oil. |
| 4、 | This instrument can measure high-voltage electrical equipment that is ungrounded or directly grounded using the positive or reverse wiring method. It can also measure the tgδ of capacitive voltage transformers and the capacitances of the 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 switching and lightning protection. During the test, it outputs high voltages of different levels from 0.5kV to 10kV, making operation simple and safe. |
Tester Parameters
1. High voltage output: 0.5 to 10kV, with each step increasing by 500V, totaling 20 steps
High voltage output cable can be used dragged on the ground
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, which uses a PID algorithm to slowly adjust the output to the set value. The measurement circuit sends the actual measured high voltage to the variable frequency power supply, fine-tuning the low voltage to achieve accurate high voltage output. According to the positive/reverse wiring 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. After the measurement is completed, the measurement circuit sends a voltage reduction command, and the variable frequency power supply slowly reduces the voltage to 0.
Precautions and Others
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,
and the instrument should be placed in a spacious, safe, and reliable location whenever possible.
2. The equipment under test must be disconnected from the high-voltage line and switched to maintenance status, cleaned, and after preliminary insulation tests show good results, 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 the wiring method based on the installation situation of the equipment, and select the corresponding wiring method in the menu options.
4. Correctly select the test voltage level according to different equipment, and choose the required voltage in the corresponding menu options.
5. In case of special situations that endanger safety 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 tests on the same equipment, press reset and 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 terminal (or secondary terminal) of the equipment under test has good insulation and measure in an environment with relatively low humidity.
8. When testing large capacitance samples, the grounding of the instrument and the grounding of the test sample should not be at the same grounding point to prevent the impact of back surge voltage or traveling waves from affecting the safety of the instrument during grounding discharge.
9. The instrument comes with a built-in 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, the power should not be suddenly turned off to avoid overvoltage damage to the equipment;
11. Although the dedicated 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; neither the high-voltage core wire nor the high-voltage shielding wire should be grounded or connected to the low-potential part of the test circuit.
The core wire and shielding wire of the CX input line must not contact the high-voltage part of the test circuit.
12. The instrument should be protected from moisture and severe vibration.
13. When on-site interference is large and power frequency measurement cannot obtain definite results, variable frequency measurement should be used; in other cases, power frequency measurement should be used.
14. If after issuing a measurement command, the measurement result does not appear on the screen for a long time (1 minute), it may be due to the test sample capacitance being too large or a system crash; restart the instrument and reduce the measurement voltage before measuring 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 at the top of the machine, press the button once to stop paper feeding. The printing paper can be pulled outward.
Instrument Structure
Measurement circuit: performs all calculations such as Fourier transform, complex number operations, range switching, and variable frequency power supply control.
Control panel: printer, keyboard, display, and communication relay.
Variable frequency power supply: uses SPWM switching circuit to produce high-power sine wave regulated output.
Step-up transformer: boosts the variable frequency power supply output to the measurement voltage, with a maximum reactive power output of 2KVA/1 minute.
Standard capacitor: internal Cn, measurement reference.
Cn current detection: used to detect the current of the internal standard capacitor, 10μA to 1A. Input resistance <2Ω.
Cx positive wiring current detection: only used for positive wiring measurement, 10μA to 1A. Input resistance <2Ω.
Cx reverse wiring current detection: only used for reverse wiring measurement, 10μA to 1A. Input resistance <2Ω.
Reverse wiring digital isolation communication: uses a precision MPPM digital modulation demodulator to transmit the reverse wiring current signal.
