Nanocrystalline vs. CRGO vs. Ferrite: The Engineer's Selection Guide
Who this comparison is for:
- • Design engineers selecting core materials for transformers and inductors
- • Procurement managers evaluating cost vs performance trade-offs
- • Product managers optimizing power electronics for size and efficiency
What you'll learn:
- • Technical comparison of magnetic properties and performance
- • Application-specific material selection criteria
- • Cost analysis and practical selection guidelines
Quick Answer:
- • Frequency < 1kHz + cost priority → CRGO
- • 10kHz-100kHz + size reduction needed → Nanocrystalline
- • MHz range + complex shapes → Ferrite
Wrong material choices show up as overheating at 50kHz, saturation during fault conditions, or enclosures that triple in size to fit the core.
This guide provides the engineering data you need to avoid those problems.
Why core material choice matters
Core material determines transformer efficiency, accuracy, size, and thermal behavior. The wrong material can lead to excessive losses, saturation, poor measurement accuracy, or oversize, costly designs.
In modern designs:
- Nanocrystalline cores are preferred where high accuracy, compact size, and wide frequency performance are needed.
- CRGO silicon steel remains the workhorse for low‑frequency, high‑power transformers where cost and saturation capability dominate.
- Ferrite is the default at very high switching frequencies where low core loss is critical.
Detailed Comparison: Nanocrystalline vs. CRGO vs. Ferrite Core Properties
Quick Summary:
Nanocrystalline offers the highest permeability and efficiency for the 10kHz–100kHz range, while CRGO dominates 50/60Hz power grids due to cost and 1.9T saturation, and Ferrite is the standard for MHz-range switching.
The table below summarizes key magnetic and practical parameters for the three materials.
| Property | Nanocrystalline | CRGO Silicon Steel | Ferrite | Engineering Note |
|---|---|---|---|---|
| Saturation Flux Density (Bs) | 1.25T | 1.9T | 0.4T | Critical for fault current handling |
| Relative Permeability (μr) | 80,000-150,000 | 30,000-50,000 | 2,000-10,000 | Enables fewer turns, smaller cores |
| Core Loss @ 20kHz, 0.1T (W/kg) | <15 | >150 | 20-80 | Data based on CenturaCores lab testing using standard toroidal samples (OD 30mm x ID 20mm x HT 10mm) |
| Curie Temperature (Tc) | ~570°C | ~750°C | ~200°C | Ferrite loses properties in hot EV engine bays |
| Operating Frequency Range | 50Hz-100kHz | 50Hz-1kHz (limited by 0.23-0.35mm lamination) | 1kHz-1MHz+ | CRGO eddy currents increase with lamination thickness |
| Mechanical Properties | Brittle (needs casing) | Robust | Moderate | Affects assembly and reliability |
| Cost per kg (relative) | 10x | 1x | 3x | But compare total system cost |
Real-World Trade-offs Engineers Face
Nanocrystalline Downsides
- • Brittle - requires protective epoxy casing
- • 10x cost premium over CRGO
- • Limited supplier base
- • Saturation at high fault currents
CRGO Limitations
- • Massive losses above 1kHz
- • Large core size for high permeability
- • Eddy current issues in switching apps
- • Poor high-frequency EMI performance
Ferrite Challenges
- • Low saturation (0.4T max)
- • Temperature-dependent properties
- • Airgap sensitivity
- • Poor low-frequency performance
Case Study: 10kW Solar Inverter Redesign
Problem: Ferrite-based EMI filter was failing conducted emissions at 150kHz.
Solution: Switched to nanocrystalline common-mode chokes.
Result: 45% volume reduction, 15dB better attenuation, same thermal profile. Cost increased 3x but avoided complete enclosure redesign.
Industry-Specific Verdicts
Best for EV Charging Stations: Why Nanocrystalline Wins on Power Density
Nanocrystalline cores are designed for applications where excellent linearity, wide dynamic range, and compact size are critical. These materials support both precision measurement and power conversion in the low‑to‑medium kHz range.
Ideal applications
- Current transformer (CT) cores for metering and protection
- EV charger transformers (typically 20–100 kHz)
- EMI filter and common‑mode choke cores
- High‑frequency power supplies operating in the kHz range
- Precision measurement equipment requiring low phase error and low magnetizing current
Benefits in these use cases include:
- • High permeability enabling fewer turns and smaller cores while maintaining accuracy
- • Low core loss and good temperature stability, improving efficiency and long‑term performance
- • Wide usable frequency range, allowing a single material family to cover CTs, EMI filters, and many power magnetics
If your CT or EMI choke keeps failing low‑frequency conducted emissions tests, switching from CRGO or ferrite to nanocrystalline is often the cleanest fix without enlarging the box.
Learn MoreBest for Grid-Scale Transformers: Why CRGO Remains the Cost-Effective Giant
CRGO silicon steel is optimized for conventional power frequencies around 50/60 Hz. It is widely used where high power and low cost are more important than size reduction or extended frequency range.
Ideal applications
- Power and distribution transformers at 50/60 Hz
- Large industrial motors and generators
- Grid‑tied equipment operating at mains frequency
- High‑power, low‑frequency transformers (on the order of kVA to MVA)
CRGO is attractive because:
- • Very high saturation flux density enables compact designs relative to older steels at 50/60 Hz
- • Established supply chains and processing techniques make it cost‑effective at scale
- • Magnetic characteristics are well understood for traditional power grids and utility equipment
For a 1 MVA transformer at 50 Hz, trying to force nanocrystalline or ferrite into the main core would usually explode your cost for little gain.
View ProductsBest for High-Frequency SMPS: When to Stick with Ferrite
Ferrite cores excel at very high switching frequencies where minimizing core loss is essential. They are standard in many SMPS and RF designs.
Ideal applications
- Switch‑mode power supplies operating above ~100 kHz
- RF transformers and broadband inductors
- High‑frequency chokes and filter components
- Flyback and forward converters in telecommunications and computing equipment
Ferrite provides:
- • Very low loss at high frequency and moderate flux densities
- • High resistivity, which greatly reduces eddy current losses at high frequency
- • A wide variety of standard shapes (E‑cores, toroids, RM cores, etc.) optimized for SMPS topologies
If the main switching is in the hundreds of kHz and you have PCB area, ferrite is almost always the first material to try before considering anything exotic.
Contact UsThe Selection Flowchart
Choose nanocrystalline when:
- • Operating frequency is roughly in the 1 kHz to 100 kHz range
- • High accuracy or low phase error is critical (e.g., CTs and precision measurement)
- • Compact size and high permeability are desired
- • The design must operate over a wide temperature range without significant drift
- • EV charging, metering, or EMI suppression performance is a key differentiator
If two or more of these bullets describe your design, shortlisting nanocrystalline early usually saves at least one design spin.
Choose CRGO when:
- • Operating frequency is 50/60 Hz or similar low frequency
- • Application involves high power (e.g., hundreds of kVA to MVA)
- • Cost is a primary driver and volume is high
- • High saturation flux density is needed at mains frequency
- • Traditional power transformers and grid‑connected equipment are being designed
If your single biggest number is kVA at 50/60 Hz, CRGO is almost always where you should start.
Choose ferrite when:
- • Operating frequency extends into the tens or hundreds of kHz and beyond
- • Very low core loss at high frequency is essential for efficiency
- • The application involves SMPS, RF, or telecommunications equipment
- • Flux density can be limited to avoid ferrite saturation while still meeting power requirements
Engineering FAQ
Q: Is nanocrystalline better than ferrite?
A: At 10-50kHz, yes - better permeability and lower loss. Above 200kHz, ferrite wins on cost and availability. Below 1kHz, both lose to CRGO.
Q: Why is CRGO still used in power transformers?
A: At 50/60Hz with MVA power levels, CRGO's high saturation (1.9T vs 1.25T nano) and low cost (1/10th) make it unbeatable. The frequency is too low for nanocrystalline's advantages to matter.
Q: Can I use nanocrystalline for everything?
A: Cost and brittleness say no. A 1MVA transformer core in nanocrystalline would cost 50x more than CRGO and crack during shipping.
Get help selecting the optimal core
Most selection questions arrive as: "My transformer is overheating at 50kHz, what core should I use?" From frequency, power level, and thermal constraints, we can usually recommend the right material family in minutes.
Real designs need more than generic charts. Waveform shape, duty cycle, fault current levels, and EMC requirements all drive the final choice.