Customizable JDCF/TYD Series 66kV–220kV Indoor High-Voltage Transformers: Technical Overview

From a distribution system design perspective, specifying the right instrument transformer means balancing measurement accuracy, fault protection reliability, and long-term substation maintainability. The Customizable JDCF/TYD Series 66kv/72.5kv/110kv/126kv/145kv/220kv Indoor High-voltage Transformers from JYDQ deliver this balance through a certified, field-proven single-phase inductive voltage transformer design. Covering 35kV through 220kV voltage classes, GB 20840 and IEC 61869 certified at a KEMA-accredited independent laboratory, these voltage transformers serve utility metering, distance protection relaying, and earth-fault detection simultaneously from a single unit per phase. The product is manufactured under ISO 9001 quality management in Zhejiang, China, and is available with three insulation technologies to match any substation architecture.

Core Specifications

Key Technical Features

1. Tri-Technology Insulation Platform

Experienced protection engineers know that insulation technology selection is determined by installation constraints, not product availability. The JDC/TYD Series addresses this by offering epoxy cast resin for compact indoor 35–66kV switchgear — including draw out switchgear configurations — SF6 gas-insulated for sealed outdoor 35–220kV installations, and oil-immersed for conventional outdoor 110–220kV substations. What distinguishes this platform is that all three variants share identical secondary winding configurations: 0.2S measuring accuracy, 3P or 6P protection accuracy, and a dedicated residual winding at 100/3 V. This means a utility deploying the JDC/TYD Series across a mixed-technology medium voltage distribution network does not need to respecify protection relay settings when switching between indoor epoxy and outdoor SF6 bays — a practical advantage that most procurement specifications underestimate until commissioning.

2. 0.2S Accuracy and Overvoltage Withstand

The distinction between standard 0.2 class and 0.2S class is not cosmetic — at substations where voltage routinely varies between 80% and 120% of rated, it translates directly into metering accuracy that the revenue settlement calculation depends on. The JDC/TYD maintains 0.2S accuracy across the full 5%–120% voltage range, while the 1.2 × Un continuous and 1.5 × Un 30-second voltage factor rating ensures the transformer remains thermally stable and magnetically unsaturated during temporary earth-fault overvoltages on isolated-neutral or resonant-earthed networks. For engineers designing protection schemes on medium voltage distribution feeders, this means the 0.2S metering winding and the 3P protection winding both remain within specification simultaneously — the VT does not need to be derated for protection during a metering period.

3. Residual Winding for Earth Fault Relay Systems

In protection scheme design, the residual voltage signal for directional earth fault relay protection is sometimes treated as an add-on — only to discover during commissioning that routing a separate zero-sequence voltage transformer significantly complicates panel wiring in a draw out switchgear bay. The JDC/TYD's integrated 100/3 V residual winding eliminates this issue: when three single-phase units are connected in broken-delta, the winding delivers up to 100 V zero-sequence voltage during a solid earth fault, driving earth fault relay schemes with no auxiliary power supply and no active electronics. This passive architecture is particularly reliable in cable-heavy networks where epr cable insulation results in higher per-unit capacitance than overhead lines, making low-current high-impedance faults the dominant fault type that current-based protection cannot detect reliably.

4. Ferroresonance-Proof Design and KEMA Certification

Every JDC/TYD unit is type-tested at a KEMA-accredited laboratory for ferroresonance withstand, covering multiple capacitive load values representative of 35kV to 220kV busbar configurations including those with epr cable insulation. The controlled-saturation magnetic core eliminates the need for external ferroresonance suppression circuits, reducing panel complexity. Routine factory acceptance testing covers dielectric withstand, accuracy verification across all windings and burdens, partial discharge (≤10 pC), polarity, winding resistance, and insulation integrity — providing the complete documentation package for grid authority pre-energization approval and multi-supplier technical comparison.

Application Scenarios

Transmission-Distribution Revenue Metering and Protection

For protection engineers commissioning 66kV to 220kV substations, the JDC/TYD provides the accuracy and voltage factor combination required to serve both metering and protection functions from a single transformer. The 0.2S class metering winding and 3P protection winding are independently rated, so specifying the JDC/TYD replaces two separate instrument transformers with one. At transmission-distribution revenue metering points, the 0.2S S-class performance ensures that energy settlement accuracy meets regulatory requirements even when grid voltage varies due to reactive power switching or renewable generation intermittency.

Indoor Switchgear and Earth-Fault Protection

The epoxy cast variant integrates directly into 35–66kV metal-clad draw out switchgear without requiring oil containment or gas monitoring equipment. The IP55 secondary terminal box and standardized terminal layout simplify wiring for both fixed-mount and withdrawable installations. Combined with the integrated residual winding, the JDC/TYD delivers earth fault relay signal, metering, and distance protection inputs from a single compact unit — reducing the number of secondary connections and the associated wiring verification effort during commissioning.

Competitive Advantages

• Dual-Standard Type-Test Certification: GB 20840 and IEC 61869 both certified at KEMA-accredited laboratories — eliminating documentation gaps for international and domestic grid authority pre-qualification. When these JDC/TYD indoor high-voltage transformers must serve projects where IEC 61869 and local grid code compliance both apply, JYDQ provides the test documentation package that satisfies both requirements.
• Integrated Earth Fault Detection: The 100/3 V residual winding delivers zero-sequence voltage for earth fault relay protection with no external devices, reducing panel count and failure modes.
• Ferroresonance-Verified Core: Eliminates external suppression circuits, reducing lifecycle cost in cable-heavy medium voltage distribution substations.
• Single-Unit Architecture: Three independent single-phase units per bay allow individual replacement without full bay outage, supporting lifecycle maintainability in 25–40-year service life substations.

Applicable Standards and Commercial Terms

The JDC/TYD Series is designed and tested in accordance with GB 20840, IEC 61869-1, IEC 61869-3, IEC 60296, and IEC 61462. The applicable standard edition and any market-specific local amendment should be confirmed with JYDQ before project specification to ensure the test documentation package satisfies the grid connection approval requirements for the project location. Payment terms are T/T or L/C at sight, FOB Ningbo or Shanghai. Supply ability is 300 sets per month. Export packaging includes reinforced wooden crates with anti-vibration insulators, desiccant packs, and shock indicators.

FAQ

1. What is the main function of voltage transformer?

Voltage transformer is a special instrument transformer. It converts high primary voltage into standardlow secondary voltage for measurement and relay protection. It isolates high voltage system fromsecondary circuit to guarantee safety for measuring and protection devices.

2. What types of voltage transformers can you supply?

We can supply cast resin indoor voltage transformer and oil immersed outdoor voltage transformer. Different types are used for medium voltage switchgear, box substation and overhead distribution network.

3. What technical parameters of voltage transformer support customization?

We can customize rated voltage ratio, accuracy class, rated output and insulation level according to yourgrid requirements. The accuracy grade can be selected for metering purpose or protection purpose.

4. What warranty service do you provide for voltage transformer?

We provide 10 years warranty for all voltage transformers. Our technical team offers remotetroubleshooting and operation guidance during the whole warranty period.