__

Gapped C-core for high current power line filters

Precision gapped GOSS C-cores designed specifically for high-current TEMPEST and facility power line EMI filters, delivering exceptional linearity and saturation resistance under heavy load.

01 · Overview

Gapped C-Cores for High Current Power Line EMI Filters

Gapped C-cores for high current power line EMI filters are precision-engineered magnetic components designed to maintain inductance and prevent core saturation under heavy continuous current loads. Unlike standard ungapped cores or powdered materials that quickly saturate, these grain-oriented silicon steel (GOSS) C-cores feature a controlled air gap that keeps the magnetic circuit linear even at high ampere-turns.

This construction is the preferred solution for TEMPEST-grade and facility power line filters, where consistent attenuation performance and thermal stability are critical. Bridgeport Magnetics manufactures these gapped C-cores in the USA using high-grade M4-011 GOSS material, offering both standard stock sizes and fully custom designs to meet the exact requirements of high-reliability EMI filter manufacturers.

02 · Superior Efficiency and Performance

Why Choose Our Gapped C-Cores for High Current Power Line EMI Filters

Bridgeport Magnetics gapped C-cores are purpose-built for the demanding requirements of high-current TEMPEST and facility power line EMI filters. Here’s why leading filter manufacturers choose our cores:

  • Superior Saturation Resistance — The precision air gap keeps the core linear under continuous high current, preventing the inductance drop that plagues powdered and ungapped cores.
  • High-Performance GOSS Material — Manufactured from premium M4-011 grain-oriented silicon steel for low core losses, high flux density, and excellent thermal stability at 50/60 Hz.
  • Controlled, Repeatable Gap — Tight manufacturing tolerances ensure consistent inductance and attenuation performance across production runs.
  • Proven Design for Critical Applications — This exact C-core construction is the industry standard for high-reliability, high-current power line filters used in military, aerospace, and secure facility environments.
  • U.S.-Made with Fast Availability — Produced in Shelton, Connecticut with stock sizes ready to ship and full custom capability for specialized current ratings or mechanical requirements.
  • Easier Assembly & Lower Total Cost — Cut C-core geometry simplifies coil winding and core stacking compared to traditional laminated EI structures, reducing labor and improving consistency.
03 · Specifications

Specifications

Amorphous C-Cores
Stock Sizes – Click on Part # to Purchase
Silicon Steel C-Cores (GOSS C-Cores) 60 Hz and 50/60 Hz Frequencies
Item Part Number VA @ 50Hz VA @ 60Hz E (mm) D (mm) F (mm) G (mm) Weight (Kg) Weight (lbs)
1 CD10x12.5×20 2 2.4 10 12.5 12.5 20 0.0832 0.18
2 CD10x12.5×25 3 3.6 10 12.5 12.5 25 0.0925 0.20
3 CD10x12.5×32 4 4.8 10 12.5 12.5 32 0.105 0.23
4 CD10x12x40 6 7.2 10 12.5 12.5 40 0.119 0.26
5 CD12.5x16x25 10 12 12.5 16 16 25 0.168 0.37
6 CD12.5x16x32 14 17 12.5 16 16 32 0.188 0.41
7 CD12.5x16x40 19 23 12.5 16 16 40 0.21 0.46
8 CD12.5x16x50 25 30 12.5 16 16 50 0.238 0.52
9 CD12.5x25x30 31 37 12.5 25 20 30 0.302 0.67
10 CD12.5x25x40 43 52 12.5 25 20 40 0.346 0.76
11 CD12.5x25x50 54 65 12.5 25 20 50 0.39 0.86
12 CD12.5x25x60 63 76 12.5 25 20 60 0.434 0.96
13 CD16x32x40 89 107 16 32 25 40 0.641 1.41
14 CD16x32x50 111 133 16 32 25 50 0.713 1.57
15 CD16x32x65 143 172 16 32 25 65 0.821 1.81
16 CD16x32x80 171 205 16 32 25 80 0.93 2.05
17 CD20x40x50 199 239 20 40 32 50 1.26 2.78
18 CD20x40x60 231 277 20 40 32 60 1.37 3.02
19 CD20x40x80 306 367 20 40 32 80 1.6 3.53
20 CD20x40x100 375 450 20 40 32 100 1.82 4.01
21 CD25x50x65 448 538 25 50 40 65 2.51 5.53
22 CD25x50x80 540 648 25 50 40 80 2.77 6.11
23 CD25x50x100 659 791 25 50 40 100 3.12 6.88
24 CD25x50x120 776 931 25 50 40 120 3.48 7.67
25 CD32x64x80 1006 1207 32 64 50 80 5.15 11.35
26 CD32x64x100 1213 1456 32 64 50 100 5.57 12.28
27 CD32x64x130 1513 1816 32 64 50 130 6.57 14.48
28 CD32x64x160 1843 2212 32 64 50 160 7.45 16.42
29 CD40x80x100 2106 2527 40 80 64 100 10.1 22.27
30 CD40x80x120 2521 3025 40 80 64 120 11 24.25
31 CD40x80x160 3214 3857 40 80 64 160 12.8 28.22
32 CD40x80x200 3912 4694 40 80 64 200 14.6 32.19
04 · Proven Across Critical Industries

Gapped C-Cores excel in high current, saturation-resistant, linear inductance, TEMPEST-grade EMI filter applications.

TEMPEST Power Line Filters

High-reliability filters requiring strict saturation control under continuous load.

Facility & Shielded Room Power Filters

High-current power entry filters for EMI-hardened rooms and chambers.

Military & Aerospace EMI Filters

Rugged high-amp filters for aircraft, ground systems, and defense platforms.

SCIF Secure Facility Filters

Sensitive Compartmented Information Facility power line filtering solutions.

High-Amperage Multi-Phase Filter Panels

Large 100–800 A three-phase panels needing linear, non-saturating inductors.

Built in Shelton, Connecticut

Let's build yours to spec.

Custom magnetics engineered and manufactured in the USA. Tell us your requirements and our engineers will help.

Request a quote →
05 · FAQ

Frequently Asked Questions

What are gapped C-cores used for in high current power line EMI filters?

Gapped C-cores are used in high current power line EMI filters to maintain linear inductance under heavy continuous loads. The controlled air gap prevents magnetic saturation, ensuring consistent attenuation performance in TEMPEST, facility, and military-grade filters.

Powdered cores often saturate at high current levels, causing inductance drop and reduced filtering effectiveness. Gapped GOSS C-cores stay linear under high ampere-turns, making them the preferred choice for TEMPEST and high-reliability facility power line filters.

Our gapped C-cores are manufactured from premium M4-011 grain-oriented silicon steel (GOSS). This material delivers low core losses, high flux density, and excellent thermal stability at 50/60 Hz for demanding EMI filter applications.

Yes. We offer both standard stock sizes and fully custom gapped C-cores designed for high-amperage multi-phase filter panels. Custom options include specific gap lengths, core dimensions, and current ratings to meet exact filter design requirements.

Yes. The gapped C-core construction is widely used in military and aerospace power line EMI filters because it provides reliable performance under high current, vibration, and temperature extremes while maintaining consistent inductance.

In facility and shielded room power filters, gapped C-cores prevent saturation during continuous high-current operation. This ensures stable filtering performance, better thermal management, and long-term reliability in secure and EMI-hardened environments.

Shopping Cart

Product Inquiry Form