Size marking on the case is the bare core dimension (OD × ID × H), not the cased or finished size.
Nanocrystalline toroidal core 40×25×15 mm
40×25×15 mm nanocrystalline toroidal core, Blue PBT Class B 130C.
CCNT-040-025-015-MFBL is a 40×25×15 mm nanocrystalline toroidal core for protective relay CTs, solid-state transformer cores, and medium-frequency power transformers. Its 25 mm inner diameter supports practical secondary windings, while high-permeability nanocrystalline material helps achieve useful magnetizing inductance at low turns. Choose this size when winding window, magnetic area, and envelope must stay in balance for the target current or VA.
Former part number: CC-NC-CMC-005-40
In stock
$15.301 piece
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Volume pricing
Online packs are $10.00 minimum. Buy packs totaling under 50 pieces. 50+ is quoted.
| Pack / qty | Unit price | How to buy |
|---|---|---|
| 1 piece | $15.30 | Buy online |
| Pack of 3 | $14.54 | Buy online |
| Pack of 5 | $13.77 | Buy online |
| Pack of 10 | $12.24 | Buy online |
| Pack of 25 | $10.20 | Buy online |
| 50+ pieces | Quoted | Request quote |
Technical Specifications
Bare core dimensions
Cased / finished dimensions
Magnetic properties
Finish and handling
Environmental
Product photos
Applications and selection
Applications
- protective relay CTs
- solid-state transformer cores
- medium-frequency power transformers
- metering CTs
- protection-class current transformers
- solid-state/medium-frequency transformer cores
- revenue-grade metering CTs
- medium-frequency (1–20kHz) isolation transformers
When to choose this size
This 40×25×15 mm toroidal core is sized for protective relay CTs and related designs in the nearby size family. Step down to the 30×20×15 mm core when board space, enclosure height, or a tighter footprint matters more than winding room. Move up to the 50×32×15 mm core when you need a larger outer diameter, winding window, or higher throughput than this part can comfortably support. In short, pick CCNT-040-025-015-MFBL when your design for protective relay CTs 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 40×25×15 mm geometry (Ae 0.92 cm², Le 10.2 cm). The winding must fit the finished window: cased ID is 21.6 mm, not the 25 mm bare ID. Keep the winding distributed around the toroid to limit leakage and local heating. 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 40×25×15 mm size marked on the case is the bare core (OD × ID × H). Finished cased size is 44.2 × 21.6 × 18.9 mm. Use bare dimensions with Ae and Le for magnetic design, and the finished inner diameter for winding clearance.
Is this core suitable for a current transformer?
Yes. It is a nanocrystalline core sized for protective relay CTs, including protection-class current transformers. High permeability helps you reach useful secondary inductance with practical turns in a 40 mm OD.
When should I choose a different size instead?
Choose the 50×32×15 mm core when you need more winding window, heavier wire, or higher throughput. Choose the 30×20×15 mm core when board space or a smaller footprint matters more than this 40×25×15 mm envelope.
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