What Is a Dielectric Withstand Tester?
A dielectric withstand tester, also known as a withstand voltage tester or dielectric strength tester, is a device used to test the insulation of electric products or components against high voltages. This tester is crucial for verifying that the insulation can prevent electrical breakdown, protect users from electrocution, or prevent fire hazards.
Safety laws specify required withstand voltages for devices to mitigate such risks. Unlike insulation resistance testers, which measure insulation performance quantitatively, dielectric withstand testers qualitatively assess the presence of dielectric breakdown by applying voltages high enough to potentially cause failure.
Uses of Dielectric Withstand Testers
Dielectric withstand testers are integral to safety standards globally, ensuring that electrical products do not suffer from dielectric breakdown. They are employed alongside insulation resistance testers and protective continuity tests in the final quality assurance stages to confirm the absence of electrical shock or leakage risks.
Principle of Dielectric Withstand Testers
Dielectric withstand testers are utilized for various tests, including:
1. AC/DC Withstand Voltage Test
A high voltage is applied for a specific period to detect even minimal current leakage, confirming the product’s safety and quality. The test involves applying voltages 10 to 20 times higher than normal operational levels to identify any sudden increases in current indicating dielectric breakdown.
2. Insulation Resistance Test
Measures the DC electrical resistance by applying up to 1,000 V DC, commonly performed during maintenance and inspections outside the manufacturing process.
3. Protective Continuity Test
Tests the product’s grounding by applying a large current between the ground post and the chassis.
4. Leakage Current Test
Simulates human electrocution scenarios by measuring leakage current through a circuit mimicking human body impedance.
Other Information on Dielectric Withstand Testers
1. Inspection and Calibration
Before use, a start-up inspection of the dielectric withstand tester is necessary to prevent injuries. Regular calibration is also essential to ensure accurate measurements. Calibration should be conducted by knowledgeable professionals every six months to several years, depending on the manufacturer’s recommendation.
2. Rental Considerations
When renting a dielectric withstand tester, it’s important to consider the required voltage, whether you’ll be testing with DC or AC, and whether digital displays are available to reduce the risk of misreading. Select a tester that meets your specific needs without unnecessary advanced features to avoid extra costs.