How cable fault are located using Megger?
Table of Contents
How cable fault are located using Megger?
This device evaluates the time difference between the acoustic signal (speed of sound) and the electromagnetic (nearly the speed of light) impulse of the shock discharge. When the shortest time difference is indicated, the exact fault location is revealed.
Which test is used for locating cable fault?
1. Blavier Test (For a Single Cable Faults) When a ground fault occurs in a single cable and there is no other cables (without faulty one), then blavier test can be performed to locate the fault in a single cable.
How do you use a cable fault locator?
To find the location of cable fault using the thumping method, a thumper is set to thump repeatedly and then walking along the cable route to hear the thumping sound. The higher the dc voltage applied, the louder will be the resulting thump. This method is useful for relatively shorter cables.
How does a fault locator work?
TWS fault locators positioned at the line ends accurately tag the arrival time of the waves using GPS as a reference. These time tags are sent to a central location where they are used to calculate the distance to fault using the line length and the velocity of propagation.
How megger test is performed?
To check whether connections are made perfectly, we use an electrical instrument named megger. In an insulation testing, we send a test voltage down through an electrical system, to check if there is any leakage of current which is gone to be passed through the insulated wiring of all the appliances of the machine.
How will you differentiate between open circuit and short circuit fault in megger?
Again, we can seek the help of a megger to check this fault. For this purpose, the two terminals of the megger are connected to any two conductors. If the megger gives zero reading, it indicates short-circuit fault between these conductors….Types of Cable Faults:
- Open Circuit Fault.
- Short Circuit Fault.
- Earth Fault.
Why do we Megger cables?
The Megger test is a method of testing making use of an insulation tester resistance meter that will help to verify the condition of electrical insulation. Insulation resistance quality of an electrical system degrades with time, environment condition i.e. temperature, humidity, moisture and dust particles.
What are the types of cable faults?
There are various types of cable faults such as earth fault, short circuit fault, and open circuit fault.
How do you Megger a power cord?
Steps
- Connect the circuit as described above.
- Press the test button on megger, the megger will generate current.
- This current flows through cable, the resistance in scale is noted which ranges between 35 to 100 Mega Ohms.
- Note to maintain this contact for 30 to 60 seconds.
What is the working principle of Megger?
Megger works on the principle of electromagnetic attraction. When a primary coil that is carrying current is placed under the vicinity of a magnetic field it experiences a force. This kind of force generates a torque that is made to deflect the pointer of the device which gives some reading.
What is the voltage used in megger?
The Megger dC dielectric Test Sets are available with voltage outputs ranging from 5 kV up to 160 kV.
What causes cable faults?
Most of the faults occur when moisture enters the insulation. The paper insulation provided inside the cable is hygroscopic in nature. Other causes include mechanical injury during transportation, laying process or due to various stresses encountered by the cable during its working life.
