How do you calculate impedance of a distance relay?

How do you calculate impedance of a distance relay?

One approach to making a distance relay with a computer is to calculate the apparent impedance Z = V 11, and then check if that impedance is inside some geometric shape, like a circle or box. The hope is that one impedance calculation (per loop) might be useful for all zones.

How do you calculate fault distance?

The fault distance is determined by assuming that the line reactance is proportional to the line length between the sending end and the fault point. Another method based on symmetrical components of the phasors and line impedances is described for locating faults on transmission lines [3].

What is mho distance relay?

A mho Relay is a high-speed relay and is also known as the admittance relay. In this relay operating torque is obtained by the volt-amperes element and the controlling element is developed due to the voltage element. It means a mho relay is a voltage controlled directional relay.

What is the Zone 1 setting of a distance relay?

Zone-1 is meant for protection of the primary line. Typically, it is set to cover 80% of the line length. Zone-1 provides fastest protection because there is no intentional time delay associated with it. Operating time of Zone-1 can be of the order of 1 cycle.

How do you calculate relay settings in PDF?

Calculation of Over Current Relay Setting:

  1. Over Load Current (In) = Feeder Load Current X Relay setting = 384 X 125% =480 Amp.
  2. Required Over Load Relay Plug Setting= Over Load Current (In) / CT Primary Current.
  3. Required Over Load Relay Plug Setting = 480 / 600 = 0.8.

How do you calculate fault current in a transmission line?

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 check for faults in transmission lines?

How to Find the Fault in Your Transmission Line

  1. Figure out the length of your cable without physically measuring the cable.
  2. Verify cable performance at the touch of a button.
  3. Determine if failures exist in your transmission line and the nature of those failures without visually inspecting the cable.

Where is mho relay used?

Mho distance relays are widely used for the protection of uncompensated and series compensated transmission lines in order to determine the presence and location of faults.

What is the purpose of mho relay?

The purpose of the Mho relay, which is also called an admittance relay is to protect the long transmission lines with heavy loads.

What is Zone 2 in distance protection?

Zone 2: Mainly intended to cover the remaining 10 % to 20 % of the Protected Line and provide Backup for the Adjoining Lines (50% of the Adjoning Length). It set to cover Remote End Busbar and Hence it is called as an Overreaching Element.

What is 3 zone distance relay?

Three Zone Distance Protection of Transmission Line : It uses a number of distance relays associated with timing relays, such that the power system is divided into a number of zones with varying tripping times associated with each zone.

What is TMS setting in relay?

Time Multiplier Setting used to change the value of operation of the relay. If it is more the relay will take more time to operate and vice versa. Changing the position of TMS setting, changes the distance between the contact of the rotating disk and the coil.

What are relay settings?

Relay settings means actual value of the energizing or characteristic quantity at which the relay is designed to operate under given conditions.

How do you calculate minimum fault current?

It is done according to IET Electrical Guidance Note 1, using the factors in Table E2 to calculate the maximum impedance of the conductor….Minimum Phase Fault Current Calculation.

t the maximum permissible disconnection time in seconds
k the cable factor
S the cross sectional area of the conductor mm2
I the minimum phase fault current

How do you calculate overhead fault?

Is Mho relay a directional relay?

Mho relay is a voltage restrained directional relay. Important Points: Reactance relay is suitable for the protection of a short transmission line because its operation is independent of arc resistance. The relay which is selected for a long transmission line should be less affected due to power swings.