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Earth fault protection is protection based on ground, or zero sequence current. If current is coming up from the ground (or going down to the ground), this protection should operate. Residual usually refers to 3*I0, which is the same as the ground current, and is the vector sum of the current in all three phases. This can be measured by connected all three phase CTs in wye, and placing a single phase overcurrent relay in the wye path to ground.
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What is the difference between balanced earth fault and restricted earth fault?
There is such a thing as a three phase to earth fault, so maybe this is what you mean by a "balanced earth fault". I don't believe any earth or ground currents would flow in this case. A restricted earth fault is a typical phase to earth fault, where the zone of protection is restricted to a specific area, such as around a transformer. "Restricted" is referring to the protection method, not what is actually going on with the currents and voltages.
Restricted earth fault protection circuit?
Restricted earth fault protection is used to protect a specific zone, and should not trip for a fault outside of that zone (usually limited to a transformer, and possibly extending to lowside, highside, and tertiary breakers).
Why is sensitive earth fault protection required?
Sensitive Earth Fault protection is required to either to alarm or trip the faulted circuit. It is usually used for resistance grounded or ungrounded systems; where first earth fault doesn't interrupt supply. It is also used on long overhead lines (even solidly grounded systems) where earth fault currents can be significantly low.
Draw and explain the operation of fault voltage ELCB and residual current device?
ELCB means Earth Leakage Circuit Breaker -- it is used to trip the Circuit breaker if any leakage fault occured means
Why is there a ground wire?
The ground earth wire serves two purposes: To trip the protection as quickly as possible if theres an out of balanced current or a fault to earth. and to bring the user to the same potential to the earth if there is a fault and the protection doesnt trip. that way because you are at the same potential as earth you will not get electrocuted.
What is the difference between balanced earth fault and restricted earth fault?
There is such a thing as a three phase to earth fault, so maybe this is what you mean by a "balanced earth fault". I don't believe any earth or ground currents would flow in this case. A restricted earth fault is a typical phase to earth fault, where the zone of protection is restricted to a specific area, such as around a transformer. "Restricted" is referring to the protection method, not what is actually going on with the currents and voltages.
Restricted earth fault protection circuit?
Restricted earth fault protection is used to protect a specific zone, and should not trip for a fault outside of that zone (usually limited to a transformer, and possibly extending to lowside, highside, and tertiary breakers).
Can earth fault current go up passing through the downstream panel and directly cause a trip at the upstream panel which have higher set point of earth fault protection?
If the fault is a direct short to ground, the fault current can be high enough to trip the upstream protection.
Why is sensitive earth fault protection required?
Sensitive Earth Fault protection is required to either to alarm or trip the faulted circuit. It is usually used for resistance grounded or ungrounded systems; where first earth fault doesn't interrupt supply. It is also used on long overhead lines (even solidly grounded systems) where earth fault currents can be significantly low.
What is an Unrestricted Earth Fault?
I'm guessing this is in reference to a restricted earth fault, and you want to know what the opposite is? Restricted earth fault protection is designed to operate for earth faults within a specific zone. Unrestricted protection will operate for faults "anywhere", as long as the pickup can be satisfied. For example, REF (restricted earth fault) transformer protection looks for a small amount of neutral current, and if this exists, and the relay identifies this current as being within the zone of protection, the relay will trip. If it were unrestricted, the small amount of neutral current alone would be enough to cause a trip.
What is the minimum Earth fault current that an Earth leakage protection unit must be able to sense?
10mA
Draw and explain the operation of fault voltage ELCB and residual current device?
ELCB means Earth Leakage Circuit Breaker -- it is used to trip the Circuit breaker if any leakage fault occured means
How is a IDMT relay used to give protection against a phase to earth fault a phase to phase fault on a feeder?
As with any IDMT relay the higher the fault current the quicker the trip time.
Why is there a ground wire?
The ground earth wire serves two purposes: To trip the protection as quickly as possible if theres an out of balanced current or a fault to earth. and to bring the user to the same potential to the earth if there is a fault and the protection doesnt trip. that way because you are at the same potential as earth you will not get electrocuted.
How does the standby earth fault scheme work?
Restricted earth fault protection is used to protect a specific zone, and should not trip for a fault outside of that zone (usually limited to a transformer, and possibly extending to lowside, highside, and tertiary breakers). Stand by earth fault protection is a term I am not very familiar with, but I believe this would be protection that is meant for a specific zone as backup, and can operate for faults outside of this zone. An example might be a highside time overcurrent relay set looking into a transformer, where the transformer is protected by a differential (primary protection), and there is a lowside feeder with relays (primary protection). The highside overcurrent acts as a backup (secondary protection) for the transformer and the feeder, and is delayed due to the nature of a time overcurrent relay.
What is residual gravity?
Residual gravity is the effective gravity that exists between the earth-moon or the earth-sun combination. When two heavenly bodies interact such as the earth and the sun there is a difference in mass which causes a residual gravity to exist in the space between them. This residual gravity is responsible for the earth's orbit.
How are residual mountains form?
Residual mountains are formed by the plates in the earth moving
