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What is a Very Low Frequency Withstand Test?

A Very Low Frequency (VLF) Withstand Test is an AC Withstand Test usually carried out at a frequency between 0.1 Hz and 0.01 Hz. This kind of test is suited for testing high capacitance loads such as cable and rotating machinery. This is a pass fail test i.e. bad cable will fail during testing rather than in service.

Introduction:

VLF Tester is designed and manufactured for electrical equipment very low frequency withstand voltage test.

Very low frequency withstand voltage test is essentially an alternative of power frequency withstand voltage test. It is much smaller, lighter and portable than power frequency withstand voltage tester. It is proved home and abroad that 0.1Hz ultra-low frequency withstand voltage test can replace power frequency withstand voltage test.

It can be applied for 10kV, 35kV, 300MW thermal power machine, 10kV, 35kV power transformer and other electrical equipment

Features:

Data of current, voltage and wave form can be directly sampled at high voltage side, so the data is real and accurate;

Over-voltage protection: If the output exceeds the set limit of voltage, the instrument will shut-down to protect itself; the actuation time is less than 15ms;

Over-current 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 15ms;

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;

As a result of high and low voltage closed-loop negative feedback control circuit, the output without capacities rise effect;

High-voltage control part adopts innovative light control HV switching unit, control is accurate, safe and reliable;

With color man-machine interface touch control plus controls modular software operating system, precise and intuitive;

Specifications:

Max voltage output: refer to following table;

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

Measurement accuracy: 2.5%;

Positive and negative voltage peak errors < 2.5%RDG+0.3%FS;

Voltage wave form distortion:<3%;

Insulation resistance measurement error:<2.5%;

Leakage current measurement error:<2.5%;

Power supply:AC220V ± 10%, 50Hz/60Hz;

Environment temperature: 0~50°C;

Humidity:≤85%RH;