Product category

VLF with dielectric loss testing

Product Description 
BVLF (Very Low Frequency) Testers are suitable for testing power cables, transformers, switchgear, rotating machinery and other electrical apparatus.
The product combines modern advanced digital variable frequency technology and micro computer control together, therefore, it can realize the full automatic voltage boost, stepdown, measurement and protection as well as the manual intervention in the process of automatic voltage boost. The full electronic design ensures the small size and light weight. The big LCD screen ensures the clear and visual display, and can display the output sinusoidal wave form. The printer outputs test reports. In addition, the product has features as follows:
1. Data of current, voltage, wave form can be directly sampled at high voltage side, so the data is real and accurate.
2. Overvoltage protection: If the output exceeds the set limit of voltage, the instrument will shut-down to protect itself, the actuation time is less than 20ms.
3. Overcurrent protection: It is high-low voltage dual protection in the design, the accurate shut-down protection can be made according to the set value at high voltage side; If the current on low voltage side exceeds the rated current, the instrument will take shut-down protection, the actuation time are both less than 20ms.
4. A high voltage output protective resistor is provided in the voltage boost body in the design and this eliminates the need of additional protective resistor connected outside.

Technical parameters:

1. Voltage (peak) 0-80kv, sensitivity: 0.1kV, accuracy: 1 %

2. Waveform: ultra-low frequency sine wave, DC voltage, positive and negative voltage peak error: ≤ 3%, voltage waveform distortion: ≤ 1%

3. Frequency range: 0.1 Hz 0.05 Hz 0.02 Hz Load range (ultra-low frequency test): 10nF-10μF

4. Current: Measurement range: 0-70 mA, sensitivity: 1 μA, accuracy: 1 %

5. Dielectric loss.

Ultra low frequency sine wave voltage range: 1-80 kVrms

Load range: 50 nF - 5 μF

Resolution: not less than 1x10-6

Accuracy: not less than 1x10-3

Measurement range: 1x10-3 - 21000x10-3

Dielectric measurement frequency: 0.1Hz

Capacitance range: 50nF-5μF

Resistance range: 30MΩ-10GΩ

Volume: 48cm*28cm*58cm

Weight: 45kg

6. Operating conditions: indoor, outdoor; temperature: -10℃～+40℃; humidity: ≤85%RH

7. Power supply: frequency 50Hz,60hz, voltage 100v -260V±5%.

8. usb communication port.

9. Use conditions: indoor, outdoor; temperature: -10℃～+40℃; humidity: ≤85%RH

10.Power supply fuse: see table 3

11. Power supply: voltage 220V±5%, 50±5Hz

12. Principle of dielectric loss test

Electrical model of cable insulation

Good insulation resistance tends to infinity; capacitive impedance is related to cable characteristics and length; resistive current is very small and in phase with the voltage; capacitive current has a fixed value and is 90° behind the voltage in phase

l The higher the resistive current, the lower the insulation capacity

l The higher the resistive current, the higher the dissipation angle δ

l The larger the angle of dissipation, the larger the tangent value

l The degree of insulation ageing can be determined by measuring the tangent of the dissipation angle