when length is increased insulation resistance of cable is decresed
i.e.,R is inversely proportional to L
where R is resistance
L is length
The insulation resistance remains the same throughout the entire length of the conductor.
The resistance of a conductor is relatively low while an insulator should have very high resistance. The former is used to transmit electricity and the latter is designed to inhibit flow of electricity.
Do you mean resistance instead of thickness?
1. phase identification test. 2. Insulation Resistance Test. 3. Conductor capacitance. 4.Conductor Resistance. 4. Outer Sheath Test.
insulation resistance can be measured by means of megger, with built in d.c generator. It is measured between the conductor and the earth. earth resistance can be measured by means of earth resistance tester. For good effective earthing, th earth resistance should be of order 0.5 ohm
insulation resistance can be measured by means of megger, with built in d.c generator. It is measured between the conductor and the earth. earth resistance can be measured by means of earth resistance tester. For good effective earthing, th earth resistance should be of order 0.5 ohm
A megger is an electrical instrument that is used to measure the resistance of insulation by applying a DC voltage to the conductor. One lead is connected to the conductor and the other lead is connected to ground. Safe insulation reading to ground should be above 2,000,000 ohms or 2 megs.
If you have 200 megohms on an insulation test of a conductor it is more than enough to feel safe about applying a voltage to the conductor with out it shorting to ground.
Values of insulation resistance vary according to the type of insulators and the size of the conducting material inside the insulators, for instance insulation resistance of wires or cables are determined according to type of insulation PVC-PE-XLPE-..... etc and the size of the conductor, and the standard which the wires or cables are designed upon. For example BS 5308 standard states that cables of conductors 0.5, 1, and 1.5 with PVC insulation should have a minimum insulation resistance of 25 Mohm.km . but cables with PE insulation should have a minimum insulation resistance of 5 Gohm.km ...... Now you may realize the difference in IR values. I hope I manage to make it clear image for the answer.
The main cause of insulation breakdown is excessive temperature. However, it can also be caused by excessively-high electrical stress due to sharp corners or other protrusions in the conductor which act to intensify the electric field beyond the capability of the insulation.
Conductor
The "current" through any conductor is voltage across the conductor/conductor's resistance .The current is measured in "Amperes" (amps)."MA" stands for "Milliamps". There are 1,000 of those in one whole ampere.So, the current through a conductor is1,000 times the voltage across the conductor/conductor's resistance . . . in MA