Cable Hipot – High Potential Test – A Complete Procedure -

First of all, the cable which is to be tested is isolated completely from both ends. And all three phases of the cable are discharged using earth rods. This makes cable free of any possible residual charges and safe to work. 

For more information, please visit Hengfeng.

220V AC power input is given to the Autotransformer through a control box, and autotransformer output is used to adjust the input voltage to the test transformer&#;s primary windings. The test transformer is used to raise the voltage to the required test level. 

As in the diagram, in the case of AC Hipot testing, secondary winding terminal of the test transformer is connected to the phase conductor of the cable. In the case of DC Hipot testing, the silicon rectifying diode is connected in series with the secondary of the test transformer. And secondary terminal of the test transformer is connected to the phase conductor of the cable through this diode. Another terminal of the secondary of the test transformer is connected to the ground along with the cable armor.

With the connections as shown in the diagram, insulation between the Phase conductor and the ground is tested. When the cable is in service and charged condition, the armor of the cable is connected to the ground, and the armor is at zero potential. Hence, with this connection insulation between phase conductor and armor is also tested. This is how the input voltage of 220 volts is raised to the required test voltage which can be 6kv to 60kv, and the Hipot test is carried out. Depending upon the insulation and voltage level of the object to be tested the test voltage is raised. 

The same procedure is repeated for the other two phases of the cable. This way we could check the healthiness of insulation between phase and earth. To check insulation healthiness between two phases, high voltage lead is connected to one phase and other lead is connected to the other phase and ground.

The company is the world’s best DC hipot tester for cables supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

IC&#;Capacitive

Capacitive (or geometric capacitive) current is also called inrush current. The windings have capacitance. Current is required to elevate its voltage potential. Capacitive current typically drops to zero within seconds after the test voltage provided by the motor tester is stable.

IA&#;Absorption

Absorption current is present during atomic and any molecular polarization of the insulation, and is the current of interest during a PI test. This current will drop to zero, or near zero, over a period of time that varies by motor. The drop can happen in seconds or may take 10 minutes or more. 

IG&#;Volume Conduction

Volume conduction current is the current that flows through the entire volume of the insulation between ground and the conductors. In good windings, this current is usually zero or near zero, and depends on the composition and condition of the insulation system. People sometimes think of this current as &#;leakage&#; current. The volume conduction current certainly leaks through the insulation, but the surface conduction current (IL) is usually the main leakage in a used motor.

IL&#;Surface Conduction

Surface conduction current is often referred to as surface leakage current. The surface conduction current runs over the end winding surfaces of the insulation.

For more information, please visit DC hipot tester for motors.

• Surface conduction is a result of surface contamination, dirt and moisture on the windings that are connected to ground.
• As the contamination level increases, the resistance of the contamination drops, and the current increases.
• As the voltage increases, the current increases more or less proportionally with the voltage applied by the motor tester.
• For used, good motors, this current will dwarf the absorption and volume conduction currents because of the relatively lower resistance in the surface contamination.
• For new, totally clean, and dry motors this current should be zero or near zero.