Electrical

What is the use of ELCB in a circuit?

What is an ELCB?

Earth Leakage Circuit Breakers are safety devices that provide additional protection against earth leakage. ELCB is employed in places where the earth impedance is high. The primary objective of these devices is to reduce the risk of shock in the event of a current flow to the earth.

When energy “leaking” to earth is detected at a level detrimental to a person using electrical equipment, an ELCB is an electrical safety device specifically intended to immediately turn off the current. Electric shock protection is provided by the ELCB.

RCD OTHER NAME OF ELCB
OTHER NAME OF ELCB

Another significant benefit of ELCBs is that they lessen the risk of fire by detecting electrical leakage to earth in electrical wire and accessories.

Purpose of ELCB in a circuit:

Even if the electric current isn’t strong enough to trip a standard circuit breaker, it can nevertheless harm or even kill a human. Without the protection provided by more sensitive circuit breakers, these charges can lurk in a piece of metal equipment.  Earth Leakage Circuit breakers are capable of detecting even minute amounts of current in malfunctioning metal electrical equipment.

ELECTROCUTION
ELECTROCUTION

Working Principle of ELCB:

The ELCB works on the principle that:

PRINCIPLE OF ELCB
PRINCIPLE OF ELCB

They function by comparing the current flow in the:

  • Active (supply) conductors and
  • Neutral (return) conductors

of an electrical circuit on a continuous basis. When the current flow in the Active conductor gets sufficiently imbalanced, some of the current in the Active conductor does not return through the Neutral conductor and leaks to earth.

Construction of ELCB in a circuit:

Every electrical device enclosure must be earthed, according to international standards. As a result, there would be no risk of electrocution. It is necessary to bury a metallic rod deep in the soil for proper operation of an ELCB, and the ELCB is connected between the wire coming from the rod and the wire attached to the external metallic body of the Electrical device, or you can say that the ELCB is connected to the Earth wire.

FLOW CHART OF ELCB
FLOW CHART OF ELCB

Operation of the ELCB in a circuit:

When the live wire (unintentionally) comes into contact with the metallic body of the connected device or appliance, a potential is created between the earthed rod and the gadget’s metallic enclosure. The circuitry (within the ELCB) detects the potential difference and switches off the main supply to the connected device when the potential difference reaches 50 volts. It safeguards the safety of human beings in this manner.

EQUIVALENT DIAGRAM OF ELCB
EQUIVALENT CIRCUIT DIAGRAM OF ELCB

Function of ELCB in a circuit:

  • Phase, Neutral and Earth are connected through ELCB.
  • ELCB working is based on the earth leakage current occurrence.
  • The human body’s safest current limit is 30 milliamperes per second.
  • Assume that the human body has a resistance of 500 ohm and that the voltage to ground is 230 volts.
  • 500/230=460mA will be the body current.
  • As a result, the ELCB must be run at 30mA/460mA=0.65msec.
FUNCTION OF ELCB
FUNCTION OF ELCB

Advantages of ELCB:

  • ELCBs are used to protect against electrical shock and are designed to function with a leakage current of less than 30 milliamps.
  • ELCB has a 30ms operating time.
  • Because of the leakage current, ELCBs are employed to defend against fire. They are designed to operate when the current is less than 100mA.

Disadvantages of ELCB:

  • If someone touches a live phase wire, the ELCB will not trip since there will be no current flowing through the earth wire. In actuality, current is travelling through the person’s body from the live wire to the earth.
  • When a live wire comes into touch with a neutral wire, a short circuit occurs, and the ELCB does not trip since the earth wire has no current.
  • There are many situations when current flows through the earth wire, but the condition is not dangerous; rather, it causes a false trip, such as when lightning strikes and current flows through the earth wire, causing the ELCB to trip.
ELCB
ELCB

Applications of ELCB:

  • ELCB instantly breaks the circuit, preventing damage to the associated circuits in residential area and commercial buildings.
  • ELCB’s are essential in moist areas where there’s a higher chance of electrical shock.

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