I. 110kV Substation Instrument Transformer Selection Scheme
In the design of a 110kV substation, instrument transformers serve as the critical bridge for High Accuracy measurement and High Insulation Reliability. Selection must comprehensively consider grid conditions, installation space, and digitalization requirements.
1. Core Product Types & Key Selling Points
Outdoor Oil-Immersed Current Transformer (CT): The mainstream choice for the 110kV level. It features a Hermes-sealed design that effectively prevents insulation oil aging (Anti-aging) and maintains excellent weather resistance and cooling performance in harsh outdoor environments ranging from -40°C to +50°C.
Epoxy Resin Cast Current Transformer (CT): Characterized by "Dry-type" Maintenance-free and fire-proof/explosion-proof features. Its Compact size makes it ideal for indoor medium-voltage switchgear or space-constrained substations.
Electromagnetic Voltage Transformer (VT/PT): Emphasizes high stability and linearity in measurement. It includes a specialized Anti-resonance design to protect against ferromagnetic resonance.
Capacitive Voltage Transformer (CVT): Highly Cost-effective at 110kV and above, while also supporting Power Line Carrier (PLC) Communication.
Combined CT/VT Unit: A "two-in-one" Space-saving design. It is the preferred choice for Revenue Metering, significantly reducing installation time and footprint.
Inverted CT (Top-head): With the center of gravity at the top and no U-type primary winding, it offers extremely low oil leakage risk and superior Seismic resistance, making it suitable for earthquake-prone areas.
Electronic/Optical Instrument Transformer (IT): Designed for Digital Substations, complying with the IEC 61850 standard. It offers inherent advantages such as No Saturation and Fiber connection for signal transmission.
2. Energy Efficiency & Technical Standards
As a designated supplier for Fortune Global 500 companies, HENGFENGYOU ELECTRIC GROUP provides solutions that meet global standards including IEC, GB, ANSI/IEEE, GOST, and SABS. Our equipment features corrosion protection up to C5M class (ISO standard) to ensure long-term operation in coastal and heavily polluted areas.
II. Design and Installation Scheme for 110kV Transformers
1. Layout and Arrangement
The arrangement of 110kV instrument transformers should align with the substation type (AIS, GIS, or HGIS). In indoor GIS or outdoor HGIS substations, transformers are often integrated within the gas-insulated switchgear to reduce land use and improve the O&M environment.
2. Key Installation Processes
Positioning and Sealing: For oil-filled types, strict inspection of all sealing surfaces is required after crane positioning to ensure a "Hermes-sealed" state.
Insulation Oil Treatment: Vacuum oil filling and hot oil circulation must be performed to remove trace moisture and gases from the insulation medium.
Secondary Circuit Grounding: The neutral point of the secondary winding must be reliably grounded at a single point to prevent high voltage from intruding into secondary equipment.
III. Commissioning and Intelligent O&M Scheme
1. Key Handover Tests
The following rigorous tests must be completed before commissioning:
Transformation Ratio and Polarity Test: To verify the correctness of secondary wiring and differential protection logic.
Accuracy Test: To ensure that metering windings meet 0.2S class or higher requirements for trade settlement.
Partial Discharge (PD) Test: To verify the reliability of the main insulation under 1.1 times the maximum operating voltage.
2. Intelligent Operation & Maintenance (O&M)
Leveraging the strategic partnership between HENGFENGYOU ELECTRIC and MINGSI Technology, we provide IoT-based smart monitoring solutions:
Real-time Monitoring: Online monitoring of partial discharge, core grounding current, and oil temperature.
Digital Remote Transmission: All operating parameters are uploaded to the control center, supporting the "Integrated Control and Maintenance" model for modern substations.
IV. Technical Overview Table for 110kV Instrument Transformers
| Dimension |
Core Content |
Recommended Solution/Standard |
| Selection |
Environment & Performance Matching |
Outdoor: Oil-immersed (Hermes-sealed) |
| Technical Specs |
Accuracy & Insulation |
0.2S Class, meeting IEC/ANSI standards |
| Installation |
Process & Protection |
Strict Vacuum Oil Filling; C5M Corrosion Protection |
| O&M Mode |
Intelligence Level |
Supports IEC 61850 & Online Monitoring |
V. About HENGFENGYOU ELECTRIC GROUP
Since its inception in 1990, HENGFENGYOU ELECTRIC GROUP has been dedicated to providing the best transmission and distribution solutions for users worldwide. With an annual output value of 120 million USD and a team of over 30 electrical engineers, we invest 6% of our revenue into R&D annually to ensure our products, including transformers and switchgear, lead the industry in energy saving and digitalization.
VI. FAQ
1. Why is "Hermes-sealed" design emphasized for 110kV outdoor CTs?
It prevents internal oil from contacting external air, slowing down oil aging and ensuring optimal cooling and service life.
2. Will electronic transformers replace traditional electromagnetic ones?
While electronic ITs are superior for Digital Substations due to no saturation, traditional types remain the standard for conventional grids due to maturity and cost.
3. How do you prevent ferromagnetic resonance in 110kV VTs?
We use specialized core designs and anti-resonance dampening devices to ensure stable linear response.
4. Is special design needed for high-altitude areas (>2000m)?
Yes, insulation and temperature rise designs are modified to account for lower air density.
5. What international certifications does HENGFENGYOU have?
Our products are certified by ISO9001, CB, CE, UL, and ROHS.
6.What is the primary use of a Combined CT/VT Unit?
It is mainly used for high-voltage Revenue Metering where space-saving and easy installation are priorities.
