VLF stands for Very Low Frequency. VLF HV Tester is an AC output high voltage instrument. VLF HV Tester provides sinusoidal AC voltage but at 0.1Hz-0.02Hz, compared to the 50/60 Hz output of conventional AC test set. It is still an AC voltage with sinusoidal polarity reversals every half cycle.

VLF HV Tester is used to field test high capacitance loads like cable and rotating machinery(motor/generator). The lower the frequency of an AC source, the lower the current and power required to apply a voltage to a capacitive load.

The principal use of VLF HV Tester is testing medium and high voltage shielded power cables. It is especially valuable for verifying a cable after installation or repair. Use the VLF to cause defects to fail during the test, find the fault, make the repair or replacement, and be left with a better cable.

VLF HV Tester is also very useful for testing large rotating machinery (motor/generator), since it provides a portable and affordable method of field testing coils and is specified by the IEEE 433-2009 standard.

The main features of Very Low Frequency HV Tester VLF-50 are as follows:

●Output frequency: 0.1Hz, 0.05Hz, 0.02Hz

●Current, voltage and waveform data are directly sampled from the high-voltage side, which ensures accurate data.

●With overvoltage protection function. When the output exceeds the set voltage limit, the instrument will stop for protection, and the action time is less than 20ms.

●With overcurrent protection function for high and low voltage double protection. High voltage side can be set according to the precise stop protection value. When the current on low-voltage side exceeds the rated current, it will be stopped for protection, and the operation time is less than 20ms.

●The high voltage output protection resistor is designed in the booster body, so there is no need to connect another protection resistor outside.

●The high and low voltage closed loop negative feedback control circuit is adopted, so the output has no capacitance rise effect.

●Test results can be saved into tester.

●Test results can be printed via built-in thermal printer.

1)Output rated voltage: 50kV/30mA(peak value)

2)Output frequency: 0.1Hz, 0.05Hz, 0.02Hz

3)Load capacity:

0.1Hz, max. 1.1µF

0.05Hz, max. 2.2µF

0.02Hz, max. 5.5µF

4)Measurement accuracy: 3%

5)Voltage positive and negative peak value error: ≤3%

6)Voltage wave form distortion: ≤ 5％

7)Working condition

temperature: -10℃~+40℃

humidity: ≤ 85％RH

8)Power supply: AC220V ±10%, 50/60Hz

Very Low Frequency HV Tester VLF-50 is powerful test instrument for measuring power cable or rotating machinery(motor/generator) at 0.1Hz, 0.05Hz or 0.02Hz.