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Korea’s KS regulations for electromagnetic compatibility testing span radiated and conducted emissions along with immunity testing. While there is substantial overlap with standards from other entities, this guide covers:
- What testing to expect, from setups to performance expectations;
- Where Korean regulations can trip up engineers used to other frameworks;
- How to design for compliance with KS EMC standards
Korea KS EMC Regulatory Snapshot
- Regulatory stack – MSIT delegates EMC oversight to the Radio Research Agency (RRA). Passing KS C 9832 (emissions) or KS C 9835 (immunity) enables issue of the KC mark, which customs uses as the single‐point compliance flag.
- Standard map - KN32 aligns with KS C 9832; KN35 aligns with KS C 9835. KN22/KN24 reports stopped being accepted after the 2017 sunset, so any fresh model must reference the newer pair.
- Scope of equipment - Multimedia, IT, and audio hardware (both RF assemblies and full products) fall directly under KS C 9832/KS C 9835 when destined for Korean commercial or consumer channels.
- Supply conditions - All tests run at the Korean utility profile of 220 VAC, 60 Hz; alternative supply variants must be exercised whenever the rating departs by more than ±10 %.
- Radiated-scan geometry From 2023 forward, RRA permits 3 m radiated sweeps below 1 GHz for small-volume gear, cutting test‐time without loosening limits.
Core KS Standards & Test Set-ups
The following cards pin down the exact KS C 9832 limit lines, KS C 9835 immunity severities, and chamber geometries you must lock before submitting a test plan:
| KS C 9832 Radiated + Conducted Emissions |
| 3 m semi-anechoic or 10 m OATS; 30 MHz – 6 GHz radiated window; 150 kHz – 30 MHz mains/telecom conduction. Class B quasi-peak limits mirror CISPR 32 tables; average detector limits sit 6 dB lower. |
| KS C 9835 Immunity Severity Matrix |
| Baseline severities equal or exceed CISPR 35: ±8 kV contact / ±15 kV air ESD, 2 kV EFT on power lines, 2 kV surge L-N, and 3 V/m radiated 80 MHz–1 GHz stepping to 5 V/m above 1 GHz. The spec mandates functional performance verification during each dwell, not simply self-recovery. |
| Test-Site Class Definitions |
| Class A equipment uses 10 m OATS below 1 GHz and 3 m above; Class B at 3 m can be done if the equipment is of small volume, i.e., if the equipment size <1.2m x 1.5m. For equipment size greater than that, a 10 m measurement is required for the full sweep if chamber correlation is documented. Shield-room damping minimum is 6 dB deeper than the numeric limit curve at every frequency, preventing ambient lift. |
| Power-Port & I/O Conditioning |
| Voltage tolerance during immunity runs is +10 %/-12 % of nominal. KS C 9835 requires separate injections on each AC phase and on every galvanic I/O longer than 3 m; surge return conductors must route directly to the panel earth to avoid chassis flashover. |
Emission vs. Immunity Contrast — KS C 9832/KS C 9835 vs. FCC Part 15 & CISPR 32/35
This contrast isolates the numerical and procedural deltas between
KS C 9832/KS C 9835 and FCC Part 15 / CISPR 32-35 that routinely force PCB or shielding tweaks:
- Regulatory reach – KS C 9832 handles emissions while KS C 9835 adds immunity; FCC Part 15 mirrors only the emission half, and CISPR 32/35 splits the pair but keeps immunity optional for the US.
- Radiated-emission baselines – KS C 9832 (KN32) sets a two-point Class B radiated-emission limit: 30 dBµV/m at 10 m from 30 to 230 MHz and 37 dBµV/m at 10 m from 230 MHz to 1 GHz (equivalent to 40 dBµV/m and 47 dBµV/m when measured at 3 m).
- FCC Part 15 Class B keeps the CISPR-style stepped curve, referenced to the same 10 m distance: 29.5 dBµV/m for 30-88 MHz, 33.0 dBµV/m for 88-216 MHz, 36.0 dBµV/m for 216-230 MHz, 35.6 dBµV/m for 230-960 MHz, and 43.5 dBµV/m for 960-1000 MHz. These convert to roughly 40 dBµV/m through 54 dBµV/m at 3 m.
- Field-strength immunity gap – KS C 9835 (KN35) mirrors CISPR 35, setting a uniform Level 3 radiated-immunity limit of 3 V/m across 80 MHz–6 GHz, with no 10 V/m requirement.
- High-band spot checks – High-band spot checks: KS C 9835 mirrors CISPR 35 by requiring discrete radiated-immunity tests at 1.8 GHz, 2.6 GHz, 3.5 GHz, and 5 GHz, points that help uncover Wi-Fi/LTE coexistence issues early, while FCC Part 15 has no comparable immunity requirement.
- Documentation load – Both KS C 9835 and CISPR 35 demand a detailed written immunity test plan that defines functional-performance criteria; generic lab templates alone are not sufficient.
Mandatory Test Categories and Performance Targets (KS C 9832/KS C 9835 Class B)
| Issue (port / phenomenon) | Pass-Target (EUT functions normally) | Key Notes / Sources |
| Radiated emission 30-230 MHz | ≤ 40 dBµV/m @ 3 m | KS C 9532 adopts CISPR 32 Class B limit-line |
| Radiated emission 230-1000MHz | ≤ 47 dBµV/m @ 3 m | Same limit family |
| Conducted emission 150 kHz-500 kHz | 66 → 56 dBµV (QP) falling-slope | Identical to EN 55032; FCC 15.107 harmonized |
| Radiated immunity 80 MHz-1 GHz | 3V/m, 80 % AM, Level 2 | KS C 9835 default chamber test |
| Radiated immunity 1.4-6 GHz | 3 V/m (spot checks at 1.8/2.6/3.5/5 GHz) | KS C 9835 chamber test |
| ESD — housing & user I/O | ± 8 kV contact, ± 15 kV air± 4 kV contact, ± 8 kV air | IEC 61000-4-2 Level 4 mapped into KS C 9835 |
| EFT/Burst — power & signal | 2 kV (5 kHz, 15 ms)1 kV (5 kHz, 15 ms) for power0.5 kV (5 kHz, 15 ms) for signal | IEC 61000-4-4 Level 3 |
| Surge — AC mains commons | 4 kV CM / 2 kV DM2 kV CM / 1 kV DM | Outdoor-cable clause, Level 4 |
| Conducted RF immunity | 10 Vrms, 150 kHz-80 MHz3 Vrms, 150 kHz-10 MHz3-1 Vrms, 10 MHz-30 MHz1 Vrms, 30 MHz-80 MHz | IEC 61000-4-6 Level 3 |
Notes: The radiated-emission numbers align with CISPR 32, so designs that already pass CE/FCC typically need only distance re-validation. Immunity, however, is materially tougher: doubling RS field strength in the first GHz, adding high-band spot bursts, and enforcing surge on outdoor cables. Plan PCB stack-up, shield stitching, and transient protection with these targets baked in.
Design-for-Compliance Pitfalls & Mitigations
As with all compliance testing, meeting Korea’s KS standards is often a matter of design choices made before the test, or at least prior to certification. Here are changes we’ve seen made to handle the regulatory framework’s requirements:
| Issue | Solution |
| Split-plane return-path gaps trigger 150–250 MHz common-mode spikes | Keep an unbroken reference under every high-edge-rate net; if a gap is unavoidable, bridge it with a 100 nF stitching capacitor at both edges. |
| Issue | Solution |
| Pi-filter / shield interaction detunes stop-band and inflates 150 kHz–10 MHz conduction | Calculate the LC corner after factoring in enclosure bond inductance; seat the filter flush to the chassis wall with 360° shield contact. |
| Issue | Solution |
| DC-DC converter harmonics ride into KS C 9832 quasi-peak bins | Lock the switcher frequency between measurement bins or apply ±20 kHz spread-spectrum, then add a high-Q LC post-filter to smother third harmonics. |
| Issue | Solution |
| Unterminated I/O shells radiate above 1 GHz | Install feed-through capacitors at the bulkhead and clamp cable shields 360° to the chassis; avoid pigtails longer than 10 mm. |
| Issue | Solution |
| KS C 9835 surge (1.2/50 µs, 2 kV L-N) overwhelms SMPS inputs | Cascade MOV then TVS, reserve ≥ 6 mm creepage, and route surge return directly to chassis ground to prevent flash-over. |
KS EMC Certification FAQs
If I replace a component, do I need to retest?
RRA treats any BOM change that alters RF characteristics or power-train topology as a new model. Minor passive-value shifts are exempt, but a silicon spin, connector swap, or clock-speed change obliges a partial KS C 9832/KS C 9835 retest.
How are multi-band radios evaluated?
KS C 9832 emissions and KS C 9835 immunity must be executed with all transmitters active in their worst-case coexistence profile; single-band data will not be accepted. Use composite firmware that forces maximum duty-cycle overlap.
What immunity head-room should I design for?
Hold a 3 dB margin over KS C 9835 severities—±12 kV air ESD and 5 V/m radiated above 1 GHz—to absorb production tolerances and line-power excursions observed during market surveillance.
Do I need an in-country representative?
Yes. RRA requires a Korean legal entity to hold technical files and respond to surveillance. MiCOM coordinates with licensed local agents and can list the domestic contact in the KC application.
Summing Up
Korea’s regulations are largely harmonized with those of the European Union and the U.S. FCC. Nevertheless, the immunity differences and the expanded testing that probes mobile-phone and other wireless bands can promptly reveal engineering oversights for teams expecting a smooth transition from FCC and CE requirements.
MiCOM Labs is an ISO 17025-accredited RF testing lab with automated MiTest® and multi-entity MiCMS® systems to quickly set up, test, and submit the required documentation for Korea’s KS standards and others worldwide. If you’re looking to partner with an expert testing organization for multi-market entry, contact us today.