Tester Parameters
1. High Voltage Output: 0.5 ~ 10kV, each step increases by 500V, total 20 steps
High voltage output cable, can be used on the ground
45Hz, 50Hz, 55Hz three frequencies
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士10% 50士1Hz
7. Harmonic Adaptation: ≤3%
8. Operating Conditions: -15℃－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 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, 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 test sample current, calculates capacitance from amplitude, and calculates tgδ from phase difference. Multiple measurements are repeated, and a middle result is selected after sorting. After measurement, 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 de-energized equipment; the grounding terminal should be reliably connected to the grounding grid,
and 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 lead from the running state to the maintenance state, cleaned, and after preliminary insulation test is good, the instrument can be used for testing to prevent the equipment under test from having poor insulation, which may damage the instrument during voltage application.
3. Determine which wiring to use according to the installation situation of the equipment, and select the wiring 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. Disconnect the power switch on the panel and clearly disconnect the 220V test power supply before changing wiring or ending work; when repeating the test on the same test equipment, you can 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 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 counter voltage or traveling waves 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 still needs to 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. When the measurement command is issued, 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 crash; restart the machine and reduce the measurement voltage before measuring again.
15. A short circuit in the test sample will make measurement impossible, and the instrument will automatically protect. When a section extends from the paper outlet above the machine head, press the button to stop paper feeding. The printing paper is allowed to be pulled out.
Measurement circuit: Fourier transform, complex number operations and all calculations, range switching, variable frequency power supply control, etc.
Control panel: printer, keyboard, display, and communication relay.
Variable frequency power supply: uses SPWM switching circuit to generate high-power sine wave regulated output.
Step-up transformer: boosts the output of the variable frequency power supply to the measurement voltage, maximum reactive power output 2KVA/1 minute.
Standard capacitor: internal Cn, measurement reference.
Cn current detection: used to detect the current of the internal standard capacitor, 10μA～1A. Input resistance <2Ω.
Cx positive wiring current detection: only used for positive wiring measurement, 10μA～1A. Input resistance <2Ω.
Cx reverse wiring current detection: only used for reverse wiring measurement, 10μA～1A. Input resistance <2Ω.
Reverse wiring digital isolation communication: uses precision MPPM digital modem to transmit the reverse wiring current signal.
