Earth Leakage Relay

Description of Earth Leakage Relay :

This relay is used on AC systems and is a sensitive electronic protective device. Its operation on Earth fault is independent of the system voltage imbalance. This relay can detect Earth fault currents as low as 1 amp. This is 0.25% in a 400 amps feeder system. This can be used on a single phase or on a three-phase network.

Principle of Operation :

This relay operates on the core balance principle wherein the currents in the three phase of the system are summed by a core balance C.T. which for normal conditions equates to zero. In case of a leakage current to earth this balance is disturbed causing the electronic circuit to operate a relay within the unit. In this event the relay that is generally connected to circuit breaker operates thus tripping the main circuit. The electro mechanical relay operates on fault. The Earth Leakage Relay is provided with a TEST push button for checking its operation and a RESET button to reset the relay on operation. This helps in checking the proper functioning of the relay.

Construction :

• The relay is housed in a robust insulated enclosure. The electronic circuit has a voltage developer, a level detector and a static switch which drives an electro-mechanical relay, the terminals of which are connected to a switch gear.
• The electro-mechanical relay operates on a fault. The Earth Leakage Relay is provided with a TEST push button for checking its operation and a RESET push button to reset the relay on operation. This built-in test feature enables the quick check of the proper functioning of the Earth Leakage Relay.
• The relay is also offered in a flush mounting design of standard, 96 sqmm.
• Type ELR Relay can be used to detect earth leakage currents upto three feeders simultaneously. However it will not indicate in which feeder the fault has occured. The relay contacts can be connected to give an alarm or otherwise made to initiate tripping of all the terminals.
• On set of N/O and N/C change over contacts can be provided.

Mounting:

The Earth Leakage Relay can be supplied in base mounting (Projection type) or 96 sqmm (door mounting). We can also supply the relays with DIP Type switches for leakage and time delay selection.

Principle of Operation:

This relay operates on the core balance principle wherein the currents in the three phase of the system are summed by a core balance C.T. which for normal conditions equates to zero. In case of a leakage current to earth this balance is disturbed causing the electronic circuit to operate a relay within the unit. In this event the relay that is generally connected to circuit breaker operates thus tripping the main circuit. The electro mechanical relay operates on fault. The Earth Leakage Relay is provided with a TEST push button for checking its operation and a RESET button to reset the relay on operation. This helps in checking the proper functioning of the relay.

Under healthy conditions ‘OK’ LED will glow. In case of any leakage current the relay will ‘TRIP’ LED will glow.

Mounting: The relay is base mounting and has built in CBCT.

This relay operates on the core balance principle wherein the currents in the three phase of the system are summed by a core balance C.T. which for normal conditions equates to zero. In case of a leakage current to earth this balance is disturbed causing the electronic circuit to operate a relay within the unit. In this event the relay that is generally connected to circuit breaker operates thus tripping the main circuit. The electro mechanical relay operates on fault. The Earth Leakage Relay is provided with a TEST push button for checking its operation and a RESET button to reset the relay on operation. This helps in checking the proper functioning of the relay. External (remote) TEST and RESET connections is also be incorporated. Under healthy conditions ‘OK’ LED will glow.

In case of Fault/Leakage Fault LED will glow and after set time delay the relay will Trip and ‘TRIP’ LED will glow along with Fault LED. On rectification of Fault the Fault LED will switch OFF but TRIP Led will glow unless and until RESET button is pressed.

Other Details:

• Option of External TEST and REST.
• Additional External LED’s for Trip and OK will be provided.
• Transformer will be coated with additional layer of resin for protection from moisture.
• Real time monitoring of CBCT wherein the relay will trip on disconnection of CBCT.
• Latching type model where the relay will Reset only on pressing of RESET button.
• LED’s for OK, Fault, CBCT Open and Trip provided in the relay.

Principle of Operation:

This relay operates on the core balance principle wherein the currents in the three phase of the system are summed by a core balance c.T. Which for normal conditions equates to zero. In case of a leakage current to earth this balance is disturbed causing the electronic circuit to operate a relay within the unit. In this event the relay that is generally connected to circuit breaker operates thus tripping the main circuit. The electro mechanical relay operates on fault. The earth leakage relay is provided with a test push button for checking its operation and a reset button to reset the relay on operation. This helps in checking the proper functioning of the relay. External (remote) test and reset connections can also be incorporated.

Under healthy conditions ‘OK’ LED will glow. In case of Fault/Leakage after set time delay the relay will Trip and ‘TRIP’ LED will glow.

Mounting:

The relay can be supplied in 96 sqmm (door mounting) or DIN rail mounting.