Size marking on the case is the bare core dimension (OD × ID × H), not the cased or finished size.
Nanocrystalline toroidal core 25×20×10 mm
25×20×10 mm nanocrystalline toroidal core, White PBT Class B 130C.
Soft-published ahead of stock. Expected availability October 20, 2026. The image is a dimension diagram; product photos will be added when inventory arrives.
CCNT-025-020-010-HFWH is a 25×20×10 mm nanocrystalline toroidal core for ground-fault/RCD pass-through sensing, EMI suppression on cable bundles, and thin-wall line filters. Its nanocrystalline HF characteristic supports common-mode and EMI filter designs where impedance and winding window matter as much as size. Choose this size when the filter or choke needs this window and OD, not the next larger footprint.
Arriving October 20, 2026
$3.421 piece
This SKU is soft-published for selection and SEO. Product photos will be added when stock arrives. Request a quote now, or join the waitlist for an in-stock notice.
Technical Specifications
Bare core dimensions
Cased / finished dimensions
Magnetic properties
Finish and handling
Environmental
Applications and selection
Applications
- ground-fault/RCD pass-through sensing
- EMI suppression on cable bundles
- thin-wall line filters
- residual-current monitoring
- residual-current device (RCD) sensing transformers
- ground-fault circuit interrupter (GFCI) cores
- cable-bundle common-mode EMI filters
- leakage-current monitoring transformers
When to choose this size
This 25×20×10 mm toroidal core is sized for ground-fault/RCD pass-through sensing and related designs in the nearby size family. Step down to the 20×12×8 mm core when board space, enclosure height, or a tighter footprint matters more than winding room. Move up to the 30×20×10 mm core when you need a larger outer diameter, winding window, or higher throughput than this part can comfortably support. In short, pick CCNT-025-020-010-HFWH when your design for ground-fault/RCD pass-through sensing fits this window and OD; pick a neighbor when compactness or power handling shifts the trade-off.
Winding notes
Magnetic calculations should use the bare 25×20×10 mm geometry (Ae 0.21 cm², Le 7.07 cm). The winding must fit the finished window: cased ID is 18 mm, not the 20 mm bare ID. Distribute common-mode windings evenly and keep leakage paths short for EMI filter performance. High permeability (μi 80,000) supports useful magnetizing inductance at practical turn counts; stay within 1.25 Tesla saturation and the -40°C to +130°C PBT Class B 130C limit.
Related application guides
Frequently asked questions
Are stated dimensions bare or cased?
The 25×20×10 mm size marked on the case is the bare core (OD × ID × H). Finished cased size is 27.5 × 18 × 13 mm. Use bare dimensions with Ae and Le for magnetic design, and the finished inner diameter for winding clearance.
Is this core suitable for EMI or common-mode filter work?
Yes. It is a nanocrystalline toroidal core commonly used for ground-fault/RCD pass-through sensing, including residual-current device (RCD) sensing transformers. Size the turns and window for your common-mode impedance target while staying within saturation and temperature limits.
When should I choose a different size instead?
Choose the 30×20×10 mm core when you need more winding window, heavier wire, or higher throughput. Choose the 20×12×8 mm core when board space or a smaller footprint matters more than this 25×20×10 mm envelope.
Related products
Nanocrystalline toroidal core 25×16×10 mm
CCNT-025-016-010-HFWH
25×16×10 mm
View CCNT-025-016-010-HFWH specsNanocrystalline toroidal core 25×16×10 mm
CCNT-025-016-010-MFBL
25×16×10 mm
Also listed as CC-NC-CMC-002-25
View CCNT-025-016-010-MFBL specsNanocrystalline toroidal core 20×12×8 mm
CCNT-020-012-008-HFWH
20×12×8 mm
View CCNT-020-012-008-HFWH specsNeed this core for your application?
Get pricing, availability, and winding support for CCNT-025-020-010-HFWH.