Ground Fault Neutralizer
The Ground Fault Neutralizer (GFN), also known as the RCC Ground Fault Neutralizer, is a novel Smart Grid protection schemel. It provides ultra-fast earth fault protection for medium and high voltage networks.
Key Principles and Technology
Novel Approach: Compensation, Not Tripping
- Instead of tripping the faulty feeder, the GFN cancels out the earth fault current by injecting an anti-phase current into the neutral.
- This interception is extremely fast and has no impact on the conveyance of payload over the faulty feeder.
- Single phase-to-ground faults can be handled without customer outage.
- This approach offers premium protection concerning personal safety and fire prevention. An interception in less than three cycles is practically unachievable by traditional protection schemes that rely on breakers
Residual Current Compensation (RCC)
- The GFN provides fast and complete compensation of all remaining earth-fault currents, including both fundamental and harmonics.
- RCC stands for Residual Current Compensation.
- Utilizing modern computer and power electronics, the GFN completely cancels out fault current and voltage injection.
- Instead of tripping the faulty feeder, the GFN cancels out the earth fault current by injecting an anti-phase current into the neutral.
- This interception is extremely fast and has no impact on the conveyance of payload over the faulty feeder.
- Single phase-to-ground faults can be handled without customer outage.
Resonance Grounding Network
- The GFN is designed to work in resonant grounded networks.
- Resonance grounding (using Petersen coils) is known for its excellent properties, resulting in very low outage rates and is common in countries like Germany and Switzerland.
- Traditionally, Petersen coils choke the fault current below the level of self-extinction (< 35.) to clear transient faults without feeder tripping.
- The GFN addresses the challenge that sustained faults on overhead lines and cable faults could previously not be cleared without tripping the feeder.
Benefits & Implementation
Benefits
- No Feeder Tripping: Single phase-to-ground faults can be handled without customer outage.
- Safety and Fire Prevention: Offers premium protection by rapidly eliminating the remaining fault current, minimizing the risk of fire and personal hazards.
- Grid Longevity: The non-tripping fault handling allows for full life cycle usage of grid assets without jeopardizing power supply quality.
- Superior Quality Investment: Cost-benefit studies indicate that resonance grounding combined with residual current compensation is one of the most cost-efficient investments for improving supply quality, leading to a substantial drop in outage rates.
- Cable Protection
Implementation
- The Ground Fault Neutralizer is connected to the neutral of the supplying power transformer (Y-winding) or a separate grounding transformer (Z-winding).
- A complete GFN system is composed of: An arc suppression coil., A cabinet for power electronics. An arc suppression coil. The GFN control cabinet.
- The GFN controls also provide automatic retuning for the arc suppression coil.
- The system includes a new twin scheme fault locating feature with superior detection capabilities.
- Distance-to-fault information can be obtained by feeder looping.
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