Guidelines

# How do you calculate fault distance?

## How do you calculate fault distance?

Fault location error: Percentage error in fault location estimate based on the total line length: e (error) = (instrument reading – exact distance to the fault) / total line length. For example, suppose a line is 100 miles long and the actual fault is 90 miles from the local terminal.

### How do you calculate fault?

Fault current calculations are based on Ohm’s Law in which the current (I) equals the voltage (V) divided by the resistance (R). The formula is I = V/R.

#### How do you calculate XR?

The X/R ratio is the amount of reactance X divided by the amount of resistance R which also happens to be the Tangent of an angle created by reactance and resistance in a circuit.

What is Zone 4 in distance protection?

There is one more Zone in modern Distance Relay which is called Reverse Zone or Zone-4. As the name Reverse Zone implies it is back-up protection of the Substation where Distance Relay is installed, in our case to the substation A. The setting for zone is normally 10% of the impedance of protected line.

What is a fault impedance?

Earth fault loop impedance is the path followed by fault current when a low impedance fault occurs between the phase conductor and earth, i.e. “earth fault loop”. The higher the impedance, the lower the fault current will be and the longer it will take for the circuit protection to operate.

## How do you find the fault in a transmission line?

In practical electricity, people use the trial and error method to detect the fault location (Line to line fault / line to ground fault) of a transmission line. They feed supply at the single end at a time by dividing that transmission line into two parts and check the fault up to that section.

### What is maximum fault current?

For single phase circuits, the maximum fault current is between the phase and the neutral and in three phase circuits it is when all phases are shorted (symmetrical current). The total impedance is that with operating temperature 20οC (lower temperature means lower resistance).

#### What is a symmetrical fault?

A symmetrical fault is a fault where all phases are affected so that the system remains balanced. A three-phase fault is a symmetrical fault. The other three fault types (line to ground, line to line, and two- line to ground) are called unsymmetrical or asymmetrical faults.

What is the XR ratio?

All Answers (3) Hitachi, Ltd. The XR Ratio of a transformer is the imaginery portion (j), of the impedance divided by the Real part. In your case considerations are: are you trying to calculate it as a network sequence or separate line entities, this makes a difference of what will result.

What is base kVA?

Voltage in equations (KV) is the secondary transformer voltage, line to line. Base KVA is 10,000 in all examples. Only those components actually in the system have to be included, each component must have an X and an R value. Neutral size is assumed to be the same size as the phase conductors.

## What is meant by 3 zone protection?

Zone 3: It is intended to give Full Backup to the Adjoning Line Section. Zone III is primarily intended to provide Backup against External Uncleared Faults and Hence set to cover the Longest Adjoining Line. It covers Full Protected Line Length and Full Adjacent line plus the Safty Margin of 20 %.

### What is Zone in distance protection?

At least three zones of protection are provided for distance relays. Zone 1 is designated by Z1 and zones 2 and 3 by Z2 and Z3 respectively. Zone 1 is meant for protection. of the primary line. Typically, it is set to cover 80% of the line length.

#### How to calculate the distance of a fault?

e (error) = (instrument reading – exact distance to the fault) / total line length. For example, suppose a line is 100 miles long and the actual fault is 90 miles from the local. terminal.

How is the fault current of a short circuit calculated?

Fault current calculations are based on Ohm’s Law in which the current (I) equals the voltage (V) divided by the resistance (R). The formula is I = V/R. When there is a short circuit the resistance becomes very small, and that means the current becomes very large.

How are fault current calculations based on Ohm’s law?

Fault current calculations are based on Ohm’s Law in which the current (I) equals the voltage (V) divided by the resistance (R). The formula is I = V/R. When there is a short circuit the resistance becomes very small, and that means the current become very large. If the resistance was zero,…

## Why are three phase faults difficult to calculate?

Most three phase faults are unsymmetrical, and that makes doing the fault current calculation more difficult. Before a fault current calculation can be performed, all of the possible sources of current must be identified.