Introduction
VLF can be used to measure insulation loss, also known as insulation dissipation factor or Tan-delta. This is usually performed over a range of test voltages, depending on the standard or guide being followed. It can be used to perform a withstand voltage method test, where the cable is subjected to an AC voltage for a specified test time without flashover. The goal is to detect potential faults in the cable insulation during a planned outage. VLF can also be used to detect and measure partial discharges in high voltage equipment. This test is usually performed over a range of test voltages to identify different defects and their initiation and extinction voltages.
Features
- Data of current, voltage, wave form can be directly sampled at high voltage side, so the data is real and accurate.
- 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.
- 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.
- 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.
Parameters
| Type |
Output
Voltage/
Current |
Load Capacity |
Control Unit |
Booster |
Fuse
Tube |
Frequency/
Capacitance |
Dim.
(cm) |
Wt
(kg) |
Dim.
(cm) |
Wt
(kg) |
| VLF-30 |
30KV/20mA |
0.1Hz ≤ 1.1uF
0.05Hz ≤ 2.2uF
0.02Hz ≤ 5.5uF |
28× 37× 22 |
4 |
33× 18× 34 |
25 |
5A |
| VLF-40 |
40KV/30mA |
0.1Hz ≤ 1.1uF
0.05Hz ≤ 2.2uF
0.02Hz ≤ 5.5uF |
28× 37× 22 |
4 |
35× 20× 36 |
35 |
6A |
| VLF-50 |
50KV/40mA |
0.1Hz ≤ 1.1uF
0.05Hz ≤ 2.2uF
0.02Hz ≤ 5.5uF |
28× 37× 22 |
4 |
37× 24× 39 |
45 |
7A |
| VLF-60 |
60KV/50mA |
0.1Hz ≤ 1.1uF
0.05Hz ≤ 2.2uF
0.02Hz ≤ 5.5uF |
28× 37× 22 |
4 |
33× 18× 34
33× 18× 34 |
25+25 |
10A |
| VLF-70 |
70KV/55mA |
0.1 Hz, ≤ 0.5µ F
0.05Hz, ≤ 1.0µ F
0.02Hz, ≤ 2.5µ F |
28× 37× 22 |
4 |
33× 18× 34
35× 20× 36 |
25+35 |
10A |
| VLF-80 |
80KV/60mA |
0.1 Hz, ≤ 0.5µ F
0.05Hz, ≤ 1.0µ F
0.02Hz, ≤ 2.5µ F |
28× 37× 22 |
4 |
33× 18× 34
37× 24× 39 |
25+45 |
12A |
Notes
- Power supply requirement: AC50Hz, 220V, stability of frequency: fluctuation less than 0.5%.
- When using it, the capacitance of the sample should not exceed the rated capacity of the instrument. The overlow capacitance of the sample will affect the output wave form. If the capacitance is less than 0.05µF, the instrument cannot output normally.
- When using it, it is prohibited to boost voltage without load, or to connect with resistive load.
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