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What should be the insulation resistance in a electrical circuit?
Wiki User
∙ 9y ago
As we know thath insulators are the materials which are mainly use to insulate any conducting body from the LIVE supply whether 3Ph or single phase, so the reristence of such an insulator should be infinity as it should be provide maximum resistance to the flow of current through it.
Wiki User
∙ 12y ago
Wiki User
∙ 9y agoA: Without insulation there will be a massive short. Insulation is provided to channel the current where it is needed to do the work.
Answer
Theoretically, the resistance of insulation should be infinity; in practice, it is measured in megohms (millions of ohms).
Wiki User
∙ 9y agoIn a perfect world the insulation factor would be infinity. This does not happen due to contamination of the insulation, water vapour or water in a conduit system are a couple of scenarios that will bring the resistance reading to a lower level. A megohm meter (megger) is the test equipment that is used to measure the insulation factor of conductors. On a 600 volt system the load can be energized with a reading as low as 500k. Engineer projects require a minimum of 5 megohm readings. Systems that have been in service for a long time usually ring in at 1 to 2 megohms.
Wiki User
∙ 14y agoIEC 60167 describes the methods of test for the determination of insulation resistance of solid insulating materials
Wiki User
∙ 12y agoIt depends on the rated nominal voltage levels of the circuits.
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How do you find shorts and opens in an electrical circuit in multimeter?
An open circuit essentially has an infinite resistance. It is shown on digital multimeter as OL. (Open Line) A short circuit should read zero, or nearly zero, depending on the accuracy of the meter.
The electrical resistance of circuit is influenced by three primary factors?
Resistance is directly proportional to the resistivityand length of a material, and inversely-proportional to its cross-sectional area. It should also be noted that its resistivity is affected by temperature, so temperature indirectly affects resistance.
What is the difference between insulation resistance and earth resistance?
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
Why multimeter cannot used for measurement of insulation resistance?
Because ordinary ohmmeters are calibrated to measure a range of resistance values that are significantly lower than the resistance of insulation. It should also be realised that we usually test insulation resistance while subjecting the insulation to a high electric field, which a normal ohmmeter is incapable of producing.
To test for resistance in a circuit should be energized or de-energized?
To test for resistance in a circuit, the circuit should be de-energized.
What is meggers?
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.
What is a short circuit how does it happen and why is it dangerous?
A short circuit is when the current in a circuit flows directly from the live/phase conductor to the neutral conductor without passing through a load. This is dangerous because the amount of current in a circuit is determined by the resistance/impedance (assuming constant voltage). The resistance of the conductor is very low and this allows large amounts of current to flow which should operate the circuits protective device (fuse). In the absence of a protective device the current will cause the conuctor toheat up first producing fumes from burning insulation and eventually seting on fire.
What are five types of insulators?
Question should be clear For Thermal insulation,Electrical insulation,energy insulation vision insulation.
What type of test should a megohmmeter be used on?
Insulation resistance.
How are Branch circuit protected?
Branch circuits are protected by the circuit breaker found in the electrical panel. Each circuit should have its one breaker. The breaker should be rated to protect the insulation of the wire, so you can determine the breaker size based on the circuit conductor size Example #14-2 should be protected by a 15 amp breaker
What happens to the value of insulation resistance of a cable when the cable gets older?
Insulation resistance should be approximately one megohm for each 1,000 volts of operating voltage, with a minimum value of one megohm. For example, a motor rated at 2,400 volts should have a minimum insulation resistance of 2.4 megohms.
Should all the materials that make up a circuit have high resistance?
No. There should be substantial resistance only where the circuit design needs it and wants it, and as little as possible everywhere else in the circuit.
What are the values for insulation resistance test?
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.
How do you find shorts and opens in an electrical circuit in multimeter?
An open circuit essentially has an infinite resistance. It is shown on digital multimeter as OL. (Open Line) A short circuit should read zero, or nearly zero, depending on the accuracy of the meter.
What is the maximum insulation resistance for a 230 volt 50hz domestic circuit if there is one Explain your answer?
This maximum insulation resistance is in the order of Mega-ohms there's a good chance the insulation resistance tester (Megger) will max out it's display to look similar to this: >99MΩor whatever your display can show. The one we used frequently in work did. It was calibrated regularly to Irish electrical standards.*Warning* If you leave lamps in place or don't disconnect electrical equipment from the wall socket you risk pumping high voltage into your device and destroying it. You must also disconnect your main earth from the board you are testing or you will back-feed to the mains incomer transformer where the Earth is neutralised and it will show a false short circuit. It goes without saying do not remove the earth if the board is live. In this case remove the earth belonging to the circuit you are testing.So, the meter tests the insulation resistance, and it does this by V/I=R or Ohm's law.Important: Voltage here is not 230vThe meter should have selectable voltages dependent on what you need to meter. But it is generally 250/500/1000 volts. For this problem we'll use 500 volts to test our cables.I (the current flowing between insulation sheaths of 2 cables, which is hopefully incredibly low, otherwise you have a short circuit) hence500/some really small number =R =Insulation Resistance500/.0001 =5,000,000 Ω5 million ohms won't register on any meter properly so you end up with the maxed out scale as discussed.Check your local Regulations for details on what is considered a pass/fail in your location. In Ireland the current Regulations say the test is fail when producing a result lower than 0.5MΩ or 500,000ΩIn theory the answer to your question is this:Infinity is the maximum insulation resistance for any circuit, however that is based on absolutely no flow of current between the two cables, which will never happen, so You'll have to do with MΩ.The only time you should be worried about insulation resistance test values is wherethe meter starts to properly register them. The smaller the final resistance, the worse the insulation is on your cable and the more likely you have a problem. Approaching 0Ωresistance it becomes clear there is a short circuit.
How do you measure electrical insulation resistance value?
By Megger testing (meggering) of the motor any one can measure the IR of the motor. MEGGER is a device used to measure IR. Analog Megger device may generate 500 volts..it gives coil to coil or coil to body IR value...it should not be less than 2 Mega ohm, generally it should be or kept more than 5 mega ohm...thanks ...DEEPAK RAJPUT
The electrical resistance of circuit is influenced by three primary factors?
Resistance is directly proportional to the resistivityand length of a material, and inversely-proportional to its cross-sectional area. It should also be noted that its resistivity is affected by temperature, so temperature indirectly affects resistance.
