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arnab ghosh
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Why are synchronous motors reactance grounded and not resistance grounded like in alternators?
Grounded as in the neutral is connected to the ground by reactor in case of motor . In case of generator , since neutral is grounded with resistance , it helps to control the current and hence suppress stability issues. But I don't get why in case of motor , neutral is grounded through reactance . Will it not lead to resonance issues and surges?Hesch said:What do you mean by "grounded"? As a safety-purpose?
I don't think that is permitted. I think that the motor (shield) must be shortcircuited to ground.
Where is the safety if the resistor/inductor is blown? Then you could act as reserve-impedance to the blown resistor/inductor.
Concerning breaking connections here in the U.S.A., neutral is virtually never broken. At least residentially, most ground fault detection is done at the receptacle. This is because most often it is the most inexpensive way to go. Not always though. The same is true in the U.S.A. concerning the ground wire. The green or bare wire and what they are connected to all the way back to the service is never meant to carry anything except a fault.Hesch said:I've tried to google "HFI-relay+US". There is not much to be found. "HFI-relay" means: "High sensitive current relay" that is measuring the ground-current (if any), using Kirchhoffs current law: Ia+Ib+Ic+Ineutral = -Iground. If Iground is above ≈20 mA, the relay will break everything (except ground) in your installation.
I think you have other rules/laws in US regarding safety, so I cannot answer your question.
Averagesupernova said:detection is done at the receptacle.
Basicly with motors you would get a ground fault with a resistive load in a wye configuration. When all three phases are closed you would have a short to groundarnab ghosh said:Why are synchronous motors reactance grounded and not resistance grounded like in alternators?
1. What is the purpose of grounding a synchronous motor with reactance?
Grounding a synchronous motor with reactance helps to reduce the likelihood of electrical shock and protect the motor from damage in the event of a fault or surge in the electrical system. It also helps to improve the overall stability and efficiency of the motor.
2. How does grounding with reactance differ from other grounding methods?
Grounding with reactance involves connecting the motor to the ground using an inductor or capacitor, whereas other methods such as solid grounding involve connecting the motor directly to the ground without any additional components. Grounding with reactance provides additional protection against electrical faults and helps to mitigate voltage imbalances.
3. Can a synchronous motor be grounded with reactance if it is already solidly grounded?
It is not recommended to ground a synchronous motor with reactance if it is already solidly grounded. This can cause issues with the motor's performance and may lead to electrical faults. It is best to consult with a professional before making any changes to the grounding of a motor.
4. What are some common types of reactance used for grounding synchronous motors?
Common types of reactance used for grounding synchronous motors include inductors, capacitors, and resistors. The specific type of reactance used will depend on the motor's size, voltage, and other electrical factors.
5. Are there any disadvantages to grounding a synchronous motor with reactance?
One potential disadvantage of grounding a synchronous motor with reactance is that it can increase the cost and complexity of the motor's electrical system. Additionally, if not done properly, grounding with reactance can cause interference with other electrical equipment. It is important to carefully consider the needs of the motor and consult with a professional before implementing grounding with reactance.