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Not all 'short circuits' are 'dead-shorts' -i.e. the resistance between the two conductors (or a conductor and earth) is not necessarily zero ohms -especially when the insulation between them has not completely broken down. The actual resistance is called the 'fault resistance'.
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∙ 11y ago
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What is leakage resistance?
leakage resistance of a resister is type of fault which occurs at a specific voltage across the resister which are undertesting.
The value of resistance of an short circuit?
The value of resistance when there is a short circuit varies depending on the nature of the fault, but it could be fractionally above zero or higher.
How designing stabilizing resistor in restricted earth fault relay?
To determine the value of Stabilizing resistor Rs = Vs/Is = If(Rct +2Rl)/Is Where, Rs = resistance value of the stabilizing resistor Vs = voltage at which the relay will operate Is = current flowing through the stabilizing resitor and the relay If = maximum secondary fault current magnitude Rct = internal resistance of the current transformer Rl = resistance of attached wire leads
Why should a earthing circuit have low resistance?
The purpose of an earthing (protective) conductor in a residential installation is to allow sufficient fault current to flow, in the event of an earth fault, to enable the operation of the circuit's overcurrent protection device (fuse or circuit breaker), so its resistance must be sufficiently low to allow this to happen.
Why is sensitive earth fault protection required?
Sensitive Earth Fault protection is required to either to alarm or trip the faulted circuit. It is usually used for resistance grounded or ungrounded systems; where first earth fault doesn't interrupt supply. It is also used on long overhead lines (even solidly grounded systems) where earth fault currents can be significantly low.
What is a bad connection in an electrical circuit called?
"A wiring fault" which - depending on the actual behavior of the bad connection - might also be described as "an intermittent fault", "a high resistance fault", or a combination of all three terms. For example: "An intermittent, high resistance wiring fault".
What is a Locked Fault?
A locked fault is a fault that is not slipping because frictional resistance on the fault is greater than the shear stress across the fault (it is stuck). Such faults may store strain for extended periods that is eventually released in an earthquake when frictional resistance is overcome.
Why resistance is neglected for fault finding?
A fault can be resistive in nature, and the amount of resistance in the fault is unpredictable. It is unusual for a fault to be inductive or capacitive, so a typical method is to determine the impedance to the fault, and compare only the inductive part of this to the inductive part of the line impedance.
What is leakage resistance?
leakage resistance of a resister is type of fault which occurs at a specific voltage across the resister which are undertesting.
Why neutral of generator is resistance grounded and neutral of motor is reactance grounded?
You can use resistance or reactance grounding on generators and motors. My understanding is resistance grounding is often used to limit ground fault currents to a few amperes, while reactance grounding will limit fault current to less than the three phase fault current. If reactance grounding is used to limit fault current o very little (like resistance grounding), transient overvoltage problems can occur.
How frictional resistance along a fault affect the force released during an earthquake?
if the frictional resistance is high, the force will be greater, and if the frictional resistance is low, the force will be smaller.
Why the high resistance earth fault in the appliance increase the risk of electric shock when using appliance in earth situation?
If the earth connection has a high resistance it is not capable of acting as a true earth. For example, the high resistance might mean that the fuse or circuit-breaker will fail to operate when there is a fault.
The value of resistance of an short circuit?
The value of resistance when there is a short circuit varies depending on the nature of the fault, but it could be fractionally above zero or higher.
Using blavier test to check for cable faults?
This is use to locate the ground fault of a single cable. This test is performed with the aid of a low voltage supply with an ammeter or voltmeter. In this test the resistance between one end of the cable C1 and the earth is first measured with the other end, C2 isolated to earth and then with the C2 earthed. Let the two readings be represented by R1 and R2 rep! If r1 and r2 are the conductor resistance of the length of cable at C2 to fault and at C1 to fault rep!, and "r" is the resistance of the fault to earth
What is the purpose of earth connection in a domestic ring circuit?
To provide a low-resistance return in the event of a earth-fault current occurring anywhere in the circuit. The requirement for a low-resistance return is to ensure the resulting fault current causes the relevant protective device to disconnect the faulty circuit.
What is a phase to phase fault?
Its is the condition when two different phases directly comes in contact with out any load or resistance.
What happens if resistance decreased in earthing?
It will work properly! The resistance and impedance of the earth lead must be low, though the corollary is that it must be capable of passing any likely fault current safely.
