The neutral grounding resistor integrated into the generator neutral cell, along with relays and current transformers, ensures the detection and limitation of fault currents.
Description
The three phases from low-voltage (LV) and high-voltage (HV) generators are combined within generator neutral cells to create a neutral point, which is grounded through a resistor.
Unlike standard neutral grounding resistors, the generator neutral cell combines the three generator phases to establish the neutral point. The primary objectives of this application are:
- Sending data to the relay via phase current transformers installed on the three phases before the neutral point.
- Limiting ground fault current to levels that prevent damage to the generator, ensuring maximum operational continuity and safety.
- Detecting faults via the current transformer connected to the neutral point of the generator neutral cell and identifying fault durations through relays.
- Limiting transient oscillatory and non-oscillatory voltage fluctuations caused by fault current interruption, thereby protecting system equipment insulation levels.
- Maintaining safe step voltage levels in the field to enhance personnel safety.
- Preventing overheating and mechanical stress on all equipment exposed to fault currents.
Technical Specifications:
- Compatibility: Suitable for generator sets up to 17.5 kV
- Current Capacity: Applicable for currents up to 5000 A
- Resistor Material: Corrosion-resistant stainless steel, designed for harsh field conditions
- Design Features: Special mechanical and electrical design to withstand high temperatures and sudden surges
- Components: Phase current transformers, neutral current, and voltage transformers
Resistor Element:
- Fault current-resistant designs, including helical winding, edge winding, or grid resistors
- Modular, braided, stainless-steel bolt-connected structure ensuring uninterrupted electrical continuity at high temperatures
- Series and/or parallel connections with braided, overlapping terminals, featuring high cross-section and low contact resistance for excellent conductivity under high currents
Cabinet:
- Designed for indoor use with excellent cooling and standard IP3X protection
- Robust, modular cell design with frame-mounted resistance blocks
- Hinged door with patented design for maximum operational safety
- Corrosion-resistant lifting lugs and fasteners
- Fully enclosed design made from 2 mm thick sheet steel
- Stainless steel product and warning labels
- Type-tested manufacturing compliant with IEC 62271-200 standards
Options:
- Custom-painted cells in requested color codes
- Auxiliary equipment, such as voltage transformers, surge arresters, panel heaters, and analog indicators
- Special designs for high-altitude operations
Tropicalized manufacturing options for corrosion resistance in tropical conditions
Advantage
- High personal and equipment safety by using fully type tested SME enclosure as per IEC 62271-200
- Easy access and maintenance
- High insulation and mechanical resistance
- Special production option against corrosion for tropical environment conditions
- Proven reliability with unique design
- Additional equipment can be included (surge arrester, panel heater, etc)
Application Area
- Thermal Power Plants
- Nuclear Power Plants
- Gas Power Plants
- Hydroelectric Power Plants
- Biomass Energy Plants
- Wind Energy Plants
