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Current transformers from YADA Electronics — a Guangdong-based manufacturer (Beijing Stock Exchange: 920556) supplying closed-core, split-core, Rogowski-coil and residual-current CTs for energy metering, industrial power monitoring and fire-protection systems. This category holds 23 current transformer models covering rated primary currents from 5 A to 6300 A in accuracy classes 0.1, 0.2, 0.2s, 0.5, 0.5s and 1.0.
Six Current Transformer Types — Which One Fits Your Application
Selecting a current transformer starts with how the conductor is routed and whether the circuit can be interrupted during installation. The table below maps YADA’s CT families to the installation situation they are built for.
| CT Type | Representative Series | Typical Rated Primary | Best Suited To |
|---|---|---|---|
| Miniature Closed-Type CT | CT Series, Closed-Type Miniature | 5 A – 1000 A | Panel-built energy meters where the busbar can be threaded during assembly; highest accuracy per unit cost. |
| Split-Core CT | SCT24L, YDKH0.66-II-B | 50 A – 300 A | Retrofit metering on live installations — the core opens around an existing cable, so no circuit interruption is needed. |
| Three-Phase Miniature CT | CTY Series | 5 A / 50 A / 100 A | Three-phase power monitoring in one compact block; saves panel space versus three single CTs. |
| Flexible Rogowski Coil | YDRS1-45 | Wide-range, class 0.5s | Large or irregular busbars, tight enclosures, and installations where a rigid core will not fit. |
| Residual / Zero-Sequence CT | Nanocrystalline Core, round & rectangular aperture | up to 1600 A | Fire-monitoring and earth-leakage detection systems requiring sensitive zero-sequence measurement. |
| High-Current Closed CT | YDBH1.2 Series | 1000 A – 6300 A | Main incoming feeders, generator and transformer outputs at 1.2 kV insulation level. |
Current Transformer Technical Specifications
The specification envelope below covers the current transformer models listed in this category. Exact values per model are stated on each product page; where a project needs a ratio outside this range, YADA builds it to order.
| Parameter | Specification |
|---|---|
| Rated primary current | 5 A, 50 A, 100 A, 200 A, 300 A, 1000 A, 1600 A, up to 6300 A |
| Rated secondary output | 5 mA, 10 mA, 20 mA, 40 mA, 100 mA, 0.1 A (milliamp outputs for direct meter input) |
| Example transformation ratios | 5 A / 5 mA · 50 A / 20 mA · 100 A / 40 mA · 100–1000 A / 0.1 A · 50–300 A / 10 mA |
| Accuracy class | 0.1 · 0.2 · 0.2s · 0.5 · 0.5s · 1.0 |
| Rated insulation voltage | AC 0.66 kV and 1.2 kV |
| Rated frequency | 50 Hz |
| Core material | Silicon steel; nanocrystalline core on residual-current and high-precision models |
| Housing | Flame-retardant PBT, high-impact grade; UL-94 V0 housings on selected sensor models |
| Aperture form | Round and rectangular apertures; split-core and flexible-coil variants available |
| Mounting | Panel, DIN rail, busbar-through, PCB pin-type direct soldering |
| Protection features | Built-in open-circuit protection on miniature closed-type CTs |
| Certification | CE certified; certificate documentation supplied with shipment |
Accuracy Class — What It Means For Your Metering Circuit
The accuracy class defines the maximum ratio error a current transformer introduces at rated conditions. Choosing the class is a commercial decision as much as a technical one:
- Class 0.1 and 0.2 — laboratory and revenue-grade metering, power-quality analysers, and applications where billing accuracy is contested. YADA supplies class 0.1 on the CTY three-phase family and 0.1/0.2/0.2s on the YDBH1.2 high-current series.
- Class 0.2s and 0.5s — the “s” designation extends the accuracy requirement down to 1 % of rated current, which matters where loads run far below the CT rating for long periods. Standard on YDRS1-45 Rogowski coils and available on YDKH0.66-II.
- Class 0.5 and 1.0 — general industrial monitoring, sub-metering, load profiling and energy-management dashboards where trend accuracy matters more than absolute billing precision.
Typical Applications
- Energy metering — single-phase and three-phase smart meters, sub-metering in commercial buildings, tenant billing.
- Industrial power monitoring — motor feeders, distribution panels, power-quality and harmonic analysis front ends.
- Solar PV and new energy — inverter output measurement, DC and AC energy metering, storage-system monitoring.
- Fire monitoring and earth-leakage detection — residual-current transformers with nanocrystalline cores for zero-sequence measurement up to 1600 A.
- EV charging infrastructure — current sensing in charging piles and energy-management systems.
How To Select A Current Transformer
- Confirm the rated primary current — size the CT to the circuit breaker or busbar rating, not the present load, so the CT remains valid when load grows.
- Choose the secondary output your meter accepts — milliamp outputs (5 mA to 100 mA) feed most modern metering ICs directly; confirm against the meter datasheet before ordering.
- Decide whether the circuit can be de-energised — if not, specify a split-core or Rogowski model so the core can be fitted around a live conductor.
- Measure the conductor or busbar — aperture dimensions and shape (round or rectangular) determine which housing fits; send the busbar dimensions and YADA will confirm the aperture.
- Set the accuracy class against how the data is used — billing and revenue metering justify class 0.1 to 0.2s; monitoring and trending are well served by class 0.5 or 1.0.
- Check insulation level — 0.66 kV covers most low-voltage distribution; specify 1.2 kV for main incoming feeders and generator circuits.
Frequently Asked Questions
Can YADA supply a custom transformation ratio?
Yes. Custom ratios, aperture sizes, secondary lead lengths, housing colours and private labelling are all supported as OEM or ODM work. Send the primary current, required output, accuracy class and installation constraints and YADA will confirm feasibility.
What is the difference between a split-core CT and a closed-core CT?
A closed-core CT has a continuous magnetic core, which gives better accuracy and lower cost, but the conductor must be threaded through it — practical only during panel assembly. A split-core CT opens on a hinge so it can be clamped around an existing energised cable, which makes it the standard choice for retrofit metering. The trade-off is a small accuracy penalty from the air gap at the joint.
Why do YADA CTs output milliamps instead of 5 A?
Milliamp outputs (for example 100 A / 40 mA) feed directly into modern metering ICs and energy-meter front ends, removing the intermediate CT and the burden resistor a 5 A secondary would require. Traditional 5 A secondaries remain available where the downstream equipment expects them.
Do the miniature CTs need external open-circuit protection?
No. Open-circuit protection is built into the miniature closed-type current transformers, so an accidentally open secondary will not develop a hazardous voltage.
Which model suits a fire-monitoring residual-current application?
Use the nanocrystalline-core residual current transformers, available with round and rectangular apertures and rated up to 1600 A. The nanocrystalline core provides the sensitivity that zero-sequence detection requires at low residual currents.
Is CE documentation provided?
Yes. The current transformer range is CE certified and certificate documentation is supplied with the shipment.
Related Product Categories
- Hall Effect Current Sensors — for DC and wide-bandwidth AC measurement where a current transformer cannot be used.
- Active Harmonic Filters — harmonic mitigation and power-quality correction downstream of the metering point.
- AC Energy Meters — metering instruments designed to pair with these CT ratios.
- DC Energy Meters — for solar, storage and EV-charging DC circuits.
- Current / Voltage Transducers — signal isolation and conversion for monitoring systems.
Request A Current Transformer Quote
Send the rated primary current, required secondary output, accuracy class and busbar or cable dimensions. YADA’s engineering team confirms the model and quotes within one working day.