Question

34 ) Calculate the earth fault loop impedance, if
the ELCB tripping current is 30 mA? | ​

Answer 1

Answer:

1666 Ω

Explanation:

The earth loop impedance, if the ELCB tripping current is 30 mA is 1666 Ω

Answer 2

The earth fault loop resistance is 1666Ohm

• It is vital as a result of EFL resistance affects the time for protecting devices to open throughout fault conditions. From basic circuit analysis, higher resistance yield lower currents, and lower resistance will yield the other.
• The following can have an effect on the worth of earth fault loop impedance: Earth Resistance ,Cable Resistance, electrical device resistance
• Among the 3 values, solely the dimensions of the cable is promptly and much be modified just in case throughout verification the EFL doesn't adapt with the need.
• In case it happened, we'd like to alter the dimensions of the cable since ever-changing the worth of earth resistance and electrical device resistance is impractical. choose succeeding higher size of cable till such time that we are able to attain the allowed EFL price.
• IEC provides specific values of EFL for various voltage levels in electrical systems so as to keep up the time needed for the protecting devices to mechanically open throughout fault condition.

Procedure on a way to live EFL by exploitation EFL tester:

• Isolate and secure the installation main switch within the off position.
• Ensure, for reasons of safety, that every one main protecting bonding is connected to the most attachment terminal. If the supplier's cable is faulty, a fault current is also introduced to extraneous components of the installation.
• Disconnect the attachment conductor from the most attachment terminal.
• Check instrument for safety and proper settings.
• Connect the planet clip to the disconnected attachment conductor, then connect the take a look at instrument line probe to the availability line terminal of the most switch.
• Press the take a look at button and note the result.
• For three-phase installations, repeat this take a look at for all line conductors. For three-phase installations, the best reading obtained is recorded because the external earth fault loop resistance.
• For a single-phase installation, record the worth.
• Reconnect the attachment conductor to the MET.
• The installation offer is also switched back on if needed.

The earth fault loop resistance is 1666Ohm

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