I. 110kV Capacitive VT (CVT) Selection Scheme
In high-voltage networks, particularly at the 110kV level and above, the Capacitive Voltage Transformer (CVT) is the preferred solution for utility companies seeking a balance between measurement precision and capital expenditure. Its unique design offers unmatched Cost-effective benefits while serving as a dual-purpose component for both power measurement and data transmission.
1. Core Product Features & Advantages
Economic Efficiency at High Voltage: As system voltages increase, the cost of electromagnetic VTs rises exponentially. The CVT utilizes a capacitive divider principle, making it significantly more Cost-effective for 110kV applications.
Integrated PLC Communication: The CVT’s capacitive divider can double as a coupling capacitor, enabling PLC (Power Line Carrier) Communication. This allows the transmission of high-frequency control signals and data over the existing power lines without extra infrastructure.
Optimized Transient Response: Our CVTs are engineered with advanced damping circuits to ensure a fast Transient response. This is critical for the accurate performance of high-speed distance protection relays during system faults.
Superior Insulation & Safety: Featuring a hermetically sealed, oil-filled capacitor stack, the CVT provides high Insulation Reliability. The design inherently limits the energy available during a fault, reducing the risk of catastrophic failure.
Ferroresonance Immunity: The electromagnetic unit (EMU) within the CVT is designed with specialized damping to suppress ferroresonance, ensuring a Stable linear output under all grid conditions.
2. Technical Standards & Global Reach
HENGFENGYOU ELECTRIC GROUP's CVTs are designed and tested according to IEC 61869-5, ANSI/IEEE, and SABS standards. Our equipment is deployed in over 50 countries, proving its reliability in environments ranging from humid tropical regions to high-altitude plateaus.
II. Design and Installation Scheme
1. System Layout
At 110kV substations, CVTs are usually mounted on steel structures at the line entrance. They are often paired with "wave traps" (line tuners) when utilized for PLC Communication to prevent high-frequency signals from entering the substation busbars.
2. Installation Key Points
Mechanical Assembly: The capacitor stacks must be handled with care to prevent any micro-cracks in the porcelain or composite housing.
Oil-Gas Integrity: For oil-filled units, the "Hermes-sealed" state must be confirmed post-installation to prevent moisture ingress.
Earthing for Communication: When used for PLC, the carrier terminal must be correctly connected to the HF (High Frequency) terminal of the CVT to ensure clear signal transmission.
III. Commissioning and Intelligent Maintenance
1. Handover Testing
To ensure the CVT meets the required performance metrics, the following tests are conducted:
Capacitance and Tan Delta Measurement: To verify the health of the capacitor stacks and insulation.
Voltage Ratio and Accuracy: Verified across the full range of the secondary burden to ensure it meets 0.2 or 0.5 accuracy classes.
Secondary Damping Verification: Testing the electromagnetic unit to confirm it effectively suppresses transients.
2. Smart Grid Integration
Aligned with the "Smart Electric Global Service Provider" mission, our CVTs support advanced O&M features:
Digital Interface: Seamlessly connects with digital merging units for IEC 61850 compliant digital substations.
Online Capacitance Monitoring: Remote sensors can track changes in capacitance, allowing for predictive maintenance before an insulation failure occurs.
IV. Technical Overview Table
| Dimension |
Core Content |
Recommended Solution/Standard |
| Selection |
Cost vs. Functionality |
Cost-effective / PLC Communication |
| Technical Specs |
System Stability |
Fast Transient Response / Anti-resonance |
| Installation |
Outdoor Layout |
Line Entry / Hermes-sealed |
| Compliance |
International Quality |
IEC 61869, CE, SABS, ROHS |
V. About HENGFENGYOU ELECTRIC GROUP
Since 1990, HENGFENGYOU ELECTRIC GROUP has been at the forefront of the power distribution industry. With 6 production sites and a dedicated team of 30 electrical engineers, we provide customized solutions for public utilities and private networks globally. Our commitment to innovation is backed by an annual 6% R&D investment, ensuring our CVTs meet the evolving demands of the global energy transition.
VI. FAQ
1. What is the primary benefit of using a CVT at 110kV?
It is significantly more Cost-effective than electromagnetic VTs at high voltages and enables PLC Communication.
2. Can a CVT be used for revenue-grade metering?
Yes, our CVTs can be manufactured to 0.2 or 0.2S accuracy classes, making them suitable for high-precision billing.
3. How does the PLC function work?
The CVT acts as a coupling capacitor, allowing high-frequency data signals to be superimposed onto the 50/60Hz power line.
4. Is the CVT sensitive to temperature changes?
Our CVTs use temperature-compensated capacitor elements to ensure stable measurement across a wide temperature range.
5. Does HENGFENGYOU offer composite insulators for CVTs?
Yes, we offer both porcelain and composite (silicone rubber) housings to suit different environmental requirements, including C5M anti-corrosion levels.
6. What is the lead time for a 110kV CVT?
Standard units typically have a production lead time of 30 days.
