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GFI's (Ground Fault Interruptors) measure the difference between the hot conductor current and the neutral current. In a normal (no fault) circuit, every single milliamp of current flowing out of the hot should return through the neutral. In other words, the two currents should be equal. If there is a ground fault, at least some of the current flows from the hot. through the fault path, to ground. In this case the neutral current is less than the hot current by however much is flowing to ground. The GFI senses this difference and trips, opening the circuit. GFI's are designed to protect equipment from damage and trip at around 30 ma. of differential current. GFCI receptacles (Ground Fault Circuit Interruptors) like the ones you might find in your bathroom, and GFCI circuit breakers are designed to protect people, and trip much lower, around 5 ma.
Wiki User
∙ 15y ago
Wiki User
∙ 14y agoIn generally, protection for ground faults. There are some outlets that include ground fault protection. These use small current Transformers to compare the current on the two power wires - this current should always sum to zero. Under a ground fault condition, current will flow out one of these, and into ground. Since the other wire never sees this current, an imballance between the two appears, resulting in the ground fault protection circuitry openning the circuit.
Wiki User
∙ 9y agoWhen an electrical circuit is working correctly the current is carried in the live and neutral wires, and there is no current in the earth wire. Therefore a current in the ground wire indicates a fault that could be dangerous, and the circuit breaker is designed to cut the supply off. In the UK this device is called an Earth Leakage Circuit Breaker (ELCB).
Answer
Under normal conditions, the current supplied to the load through the line conductor is identical to the current returned to the supply through the neutral conductor. A GFI monitors these currents and, when there is any imbalance the device trips. The imbalance is due to a ground fault. GFIs are designed to protect users, rather than the circuit or the load and operate faster than circuit breakers.
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In relation to electric what does the term fault protection mean?
Protective devices - relays, CT,PT, isolators, circuit breakers are used for fault protection. Fault protection means If there is a fault in the circuit, the circuit must be cut off before any damage occurs due to fault.
Is a ground fault protection for equipment required even if the neutral will not be used?
Yes, ground fault protection for equipment is requiredeven if the neutral will not be used.However, the question implies that it might not be required if there is a neutral. That is not true. With two exceptions, ground fault protection is always required in the US, and it is probably required in other countries as well.The exceptions are the use of an electric cooking range, and an electric clothes dryer. In those cases, the US NEC allows the neutral conductor to also be the ground fault conductor, except for the case where the range or dryer is in a mobile home. In the case of the mobile home, the ground fault conductor and the neutral conductor must be maintained separate and distinct all the way back to the distribution panel.In every other case, including where local code overrides the US NEC's exceptions, it must be understood that ground fault protection (protective earth ground) is not the same as neutral, even though the neutral conductor is grounded.
In 3 pH Delta motor connection the upstream ACB is tripping due to ground fault protection while motor starts with soft starter why?
Check the earth fault trip off set limit of the ACB. It may be too low.
How can you have a ground fault protection in a 3 phase 3W system?
3 phase ground fault detection on a 3 phase system requires that the vector summation of all three phase currents be measured. The vector sum of these currents should equal zero, or nearly zero for a balanced system. If a ground fault exists, then the vector sum will not equal zero. This condition must be validated using i2t techniques in order to eliminate false trips.
What is neutral to ground fault?
Neutral, by definition, is grounded at the distribution panel, and also at the distribution pole. That is how the hot to ground voltages are prevented from exceeding their normal voltage and encroaching on truly lethal voltages, such as 7.6kV in a typical US 13.2kV system, in a wye configuration.Note: and this is critical, do not depend on the fact that neutral is grounded and consider that it is the same as protective earth ground. It is not. Protective earth ground is a different wire.
In relation to electric what does the term fault protection mean?
Protective devices - relays, CT,PT, isolators, circuit breakers are used for fault protection. Fault protection means If there is a fault in the circuit, the circuit must be cut off before any damage occurs due to fault.
What is neutral grounding resistor panel?
A neutral grounding resistor panel is used to resist fault current to the ground. It is used for alternator protection protection purposes. When a fault occurs in the alternator, the panel helps force the current to the ground.
Does water pump has ground fault protection?
A stand alone water pump does not have ground fault protection within the motor body. The ground fault protection has to come from equipment that is situated upstream from the pump. It can be in the form of a GFI breaker that supplies the voltage to the pump. Larger size pumps usually use a stand alone GFI that is hard wired to the supply breaker and then the pump is hard wired to the GFI unit.
What is residual earth fault protection?
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.
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.
Is a ground fault protection for equipment required even if the neutral will not be used?
Yes, ground fault protection for equipment is requiredeven if the neutral will not be used.However, the question implies that it might not be required if there is a neutral. That is not true. With two exceptions, ground fault protection is always required in the US, and it is probably required in other countries as well.The exceptions are the use of an electric cooking range, and an electric clothes dryer. In those cases, the US NEC allows the neutral conductor to also be the ground fault conductor, except for the case where the range or dryer is in a mobile home. In the case of the mobile home, the ground fault conductor and the neutral conductor must be maintained separate and distinct all the way back to the distribution panel.In every other case, including where local code overrides the US NEC's exceptions, it must be understood that ground fault protection (protective earth ground) is not the same as neutral, even though the neutral conductor is grounded.
What sort of protection scheme do you suggest for the protection of a 10 HP motor?
1)Instantaneous overcurrent protection. 2.Ground fault protection. 3.Thermal overload protection. 4.Stalling Protection. 5.Phase unbalance protection.
What is meant by earth fault protection?
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.
What can fuses not provide protection against?
Fuses do not provide protection against ground faults. Protection against a ground fault can be provided by breakers. If a fuse blows, it has to be replaced. If a breaker is tripped to off due to a surge in electrical current, the breaker can be reset.
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).
What is the GFCI?
A "GFCI" is a ground fault circuit interrupter. For more information see the link below.
What is 50G protection relay mean?
50 is the ANSI device number for an instantaneous overcurrent relay. The G suffix stands for "ground." A 50G protection relay trips the circuit breaker without time delay when it detects a ground fault on the circuit.
