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Is Your Cable Up To The Job? AC or DC Hipot Tests Will Tell

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What does it mean for electrical cable to be “up to the job”? Well, it needs to do two things. First, it should be able to carry current from one place to another along the conducting wire. In order to do this safely and efficiently, it next must ensure that nothing can flow through the insulation layer. 

The hipot test applies a high voltage between conductor and earth across the insulation. This is accomplished with either an alternating supply (AC hipot) or a DC supply (DC hipot). Whichever type of equipment you decide to use, the principle is the same. You’re going to fire a high voltage across the insulating layer in order to be sure it doesn’t break down. By “break down” it means that no electricity flows through the insulating layer. 

For a multiple-strand cable, one strand will be connected to the voltage source while the others are held at zero volts. The current flowing through the circuit is then measured. It is beyond the scope of this post to discuss the difference between resistive and capacitive flow but what is required is to measure resistive flow in order to assess the quality of the cable’s insulation. Cable test equipmentsoftware allows the two types of current to be separated and gives you a report of the resistive current flowing and hence the quality of the cable. To find out more about capacitive and resistive current flow, see our previous post “Why do I need a Power Factor Test?”

Our short and long term rental program will help you find just the right hipot and other test equipment your project needs. Be sure to give us a call or contact us online