| Q. |
What is a Hipot? |
| A. |
A Hipot (which is an acronym for high potential) is a testing instrument used to verify the integrity of an electrical product's insulation.
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| Q. |
What is a Hipot test? |
| A. |
This test, also known as the Dielectric Withstand test, is used to stress the insulation of a product far beyond what it would it encounter during normal operation. High voltage is applied from the mains-input lines to the chassis of the product for a specified length of time to check the integrity of the insulation by monitoring resulting leakage current. The hipot test is a 100% production line test and can be performed using either an AC or a DC voltage. |
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| Q. |
What is a Dielectric Voltage Withstand test? |
| A. |
A Dielectric Voltage Withstand test is another name for a Hipot test. The two terms are used interchangeably in the industry. |
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| Q. |
What types of tests does a Hipot perform and what types of manufacturing and service problems does it detect? |
| A. |
The Hipot Test stresses the insulation between the current carrying and non-current carrying parts of a product for excessive current leakage flow. This test is ideal for detecting workmanship errors, design problems as well as component spacing problems. The area hipots are typically used include:
- Production line
- Research and Development Labs
- Incoming Inspection Areas
- Repair Areas
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| Q. |
How do I determine the proper Hipot test voltage for my application? |
| A. |
The best way to determine this is to check the specification you must comply with for your tests. Typically the "rule of thumb" for an AC test voltage is (2 * operating voltage + 1,000 volts). So if your products operating voltage is 115 volts AC the answer would be (2 * 115) + 1,000 = 1,230 volts. Test voltages may vary depending upon the classification of the product. |
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| Q. |
How do I determine the proper Hipot current trip point for my application? |
| A. |
Unlike the case of test voltage, there is no leakage "rule of thumb" for the current trip setting. Sometimes acceptable leakage levels are determined by testing a sampling of products that can provide acceptable ranges. Some UL specifications call for a leakage adjustment to be made with a 120kΩ resistor across the Hipot test leads. Contact your local safety agency office or our Technical Services department for more information. |
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| Q. |
How do I determine if I need to test with an AC or DC voltage? |
| A. |
The type of test voltage you must use during a test may or may not be specified by the safety agency's standard you are using. If it is not specified, you may usually use either an AC or DC output voltage. However, there are different considerations to take into account when using a DC voltage. Contact your local safety agency office or our Technical Services department for more information. |
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| Q. |
Should the power switch of my product be turned on during a Hipot test ? |
| A. |
Yes. In order to be sure current flows throughout the entire insulation system, all power switches must be set to the on position. |
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| Q. |
What is the VA rating of a Hipot? |
| A. |
The VA or (Volt-Amp) rating is the power output of the instrument and is determined by multiplying the maximum output voltage by the maximum current. For example 5,000 volts * 100 milliamps = 500VA. |
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| Q. |
Is the AC output of a Hipot indicated in RMS? |
| A. |
AC output can be monitored in peak, peak-to-peak or RMS voltages. Since most DUT's operate on RMS voltages during normal operation the Hipot test should also be measured in RMS. |
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| Q. |
Is there a difference between DC and AC Hipot tests? |
| A. |
Yes. The difference becomes most noticeable when testing highly capactive DUT's. Since AC voltages cannot charge a capacitive load, reactive current flows instantly and remains consistent regardless of the time the voltage is applied. DC voltages will charge the capacitance of the DUT so you may see an inrush of current upon initial application of the voltage but gradually the readings will dissipate as the DUT becomes charged. As a result of this phenomenon, current readings will usually differ between an AC and DC Hipot test. |
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| Q. |
How can I determine if my Hipot is functioning properly and how often should I check it? |
| A. |
Verifying the failure detection circuitry of electrical safety testers is required by safety agencies. This test is normally required to be performed at the start of each shift to validate that the instrument is functioning correctly. |
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