The VLF AC Hipot Tester under Wuhan UHV can help many power workers conduct various power tests more conveniently.
Hipot test (high voltage test): This is a general term that refers to applying a test voltage much higher than its normal operating voltage to electrical equipment (such as cables, motors, transformer windings), with the aim of evaluating its insulation strength and discovering potential defects (such as cracks, air gaps, contamination, degradation).
VLF testing (very low frequency testing): This is a specific form of AC Hipot testing. It uses sine or cosine square wave voltage with a very low AC frequency (usually 0.1 Hz, which is a complete cycle every 10 seconds) for testing. VLF is essentially a special type of AC Hipot test.
1.Core Nature:
Hipot Test: An umbrella term for tests applying high voltage to verify insulation strength.
VLF Test: A specific type of Hipot test using Very Low Frequency AC (0.1 Hz).
2.Voltage Type:
Hipot (Typically DC Hipot): Uses Direct Current (DC).
VLF: Uses Very Low Frequency AC (0.1 Hz AC).
3.Defect Detection Strength:
Hipot (DC): Best for detecting concentrated "hard" defects (e.g., major cracks, voids).
VLF (0.1Hz AC): Best for detecting distributed aging defects, especially water trees in cables. Its AC stress also better simulates real operating conditions.
4.Primary Application:
Hipot (DC): Traditional field testing (finding major faults), some factory tests. Being phased out for cable testing, replaced by VLF.
VLF: The preferred method for field testing modern medium-voltage cables (especially XLPE) (acceptance & maintenance) as it effectively detects their main aging mechanism (water trees) and is portable.
Simplest Summary:
Hipot is the general term (often meaning DC), good for finding major damage quickly.
VLF is a Very Low Frequency AC Hipot test. It's better and safer for finding water tree aging in cables and is the mainstream method for field cable testing.