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Earth fault protection is called ground fault protection in the US. It is a device that monitors the separation of the hot and ground wires in your house's electrical system. If it detects that the hot and ground have been connected with too low of resistance--like when you drop an appliance into water--it will disconnect the hot line so you won't get shocked.
It's not intended to be used this way, but if you want an outlet you can switch on and off and you don't want to pull wire, install a ground fault protected outlet. If you push the "test" button the outlet will be switched off, and pressing the "reset" button turns it back on.
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∙ 12y ago
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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).
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.
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
What is meant by ground fault?
The ground ('earth'), because of its mass, is a reasonably-good conductor and is used as a 'reference' for a distribution transformer's neutral terminal. A ground fault ('earth fault') occurs when the line conductor from the distribution transformer makes accidental contact directly with the ground ('earth'). The resulting low-resistance earth path back to the transformer's neutral is such that the resulting ground-fault current('earth-fault current') will operate the transformer's overcurrent protection device (e.g. fuse).
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.
Calculation of restricted earth fault relay stabilizing resistor?
Requirement of REF protection for 50KVA 11KV/.4KV transforemr
What is difference between isolation transformer and earth protection relay?
An isolation transformer is a mutual transformer having a voltage ratio of 1:1, so that the secondary circuit is electrically isolated from the primary circuit, yet subject to the same voltage.An earth protection relay is a category of protective relay that responds to an earth fault monitored by a current transformer (CT). In the event of an earth fault being detected by the CT, the relay with activate the trip circuit to a circuit breaker which will then disconnect the fault.
