CISPR 25 — Vehicle Components Emission Test

What Is CISPR 25?

CISPR 25 is the standard for measuring radiated and conducted emissions of electrical and electronic components for the protection of in-car radio receivers. Defines boundary classes from Class 1 to Class 5.

Purpose of CISPR 25

The purpose is to verify that the component does not emit enough interference to affect the radio and communications receivers on the vehicle.

Which Products Is CISPR 25 Applied To?

Electronic control units
Electric motors and drives
DC-DC converters and inverters
Lighting modules
Charger and OBC

In Which Sectors Is CISPR 25 Used?

ElectronicsElectricalAutomotiveTelecommunicationsDefence

Standards Related to CISPR 25

CISPR 25Radio degradation of in-car components test
UNECE R10electromagnetic compatibility in vehicles test
ISO 11452 (immunity side)

CISPR 25 Conditions

radiant emission: Typically 150 kHz – 2.5 GHz; Divided by antenna type
Conducted emission: Voltage method (150 kHz – 108 MHz) and current probe method
limit class: Class 1 – 5; determined in customer specification
test layout: Anechoic chamber, reference ground plane and defined harness length

Equipment for CISPR 25

Anechoic chamber and ALSE scheme
EMI receiver
Monopole, biconical, log-periodic and horn antennas
LISN and current probe
load simulators

Sample Requirements for CISPR 25

Wire harness length and layout must comply with the standard
Load simulator and feeding arrangement must be documented
The worst-case operating mode must be determined
The sample should be placed on the reference plane at a defined height.

Duration of CISPR 25

It depends on the frequency range and number of operating modes; typically one to three business days.

CISPR 25 Procedure

1The boundary class and the methods to be applied are determined.
2The sample, wiring harness and load simulator are installed according to the standard.
3The worst-case operating mode is determined by a preliminary scan.
4Conducted emission (voltage and current) is measured.
5Radiated emission is scanned by changing antenna types.
6Results are compared with the class limits.

CISPR 25 Acceptance Criteria

The acceptance criterion is the emission limits of the selected limit class. As the class number increases, the boundaries become stricter.

Evaluation of Results

Emission charts are presented with border lines and margin is indicated. Switching frequency harmonics are typical critical regions.

CISPR 25 Report

Applied standard and limit class
Test pattern and wiring harness information
Operating modes
Radiated and conducted emission graphs
Margins and measurement uncertainty

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

UNECE R10
Automotive OEM EMC specifications

EMC / EMI Testleri — What Does This Testing Field Cover?

The section below describes the field that the CISPR 25 test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

EMC testing answers a question with two sides: does the device emit an unacceptable level of electromagnetic interference into its surroundings (emission), and does it withstand the interference coming from them (immunity)? The two sides are measured with separate tests and separate set-ups, and both are required.

The field exists because of a simple physical fact: every conductor carrying current behaves like an antenna. A switched-mode power supply, a motor drive or the clock signal of a microcontroller radiates radio frequency energy even though it was never designed to. The same conductor also works in reverse: an external field induces a voltage across it. In an environment crowded with devices, this mutual effect means devices disturbing one another.

On the emission side, conducted and radiated emission are measured separately. Conducted emission is the interference the device imposes on its mains and communication cables and dominates at lower frequencies. Radiated emission is the field the device releases into the air and comes to the fore at higher frequencies. The two are measured in different set-ups, and the limits vary by product group.

On the immunity side, real-world sources of interference are simulated: electrostatic discharge (human touch), radiated radio frequency fields (a nearby transmitter), electrical fast transients (switching), surges (lightning and mains events), conducted radio frequency, power-frequency magnetic fields, voltage dips and short interruptions.

The standard to be applied depends on WHERE the product is used, and that choice determines the entire outcome. Residential and industrial environments carry different sets of limits; in vehicles the UNECE R10 regime applies rather than CE; for medical devices IEC 60601-1-2 brings additional requirements; and for products containing a radio, radio legislation comes into play and harmonised ETSI standards are used.

In immunity testing the acceptance criterion is a PERFORMANCE CRITERION class, not a binary pass/fail. A device continuing to function without interruption during the test, being temporarily affected and recovering by itself, or recovering only through user intervention are different classes. Which class is acceptable is defined in the product standard; the tolerance for a device carrying a safety function differs from that of a consumer device.

The most common shortcoming of an EMC file is that it covers only one side. A file carrying an emission report alone is not complete in terms of the EMC directive. The second common gap is a test set-up that does not represent actual use: if the device is measured on a bare bench with cables different from its real ones, the result does not carry over to the field.

Method groups in this field

Conducted emission
Interference imposed on the cable through mains and communication ports, measured via an artificial mains network (LISN).
Radiated emission
The field released into the air by the device, measured at a defined distance in an anechoic or semi-anechoic chamber.
Harmonics and flicker
The harmonic content of the current drawn from the mains and voltage fluctuation; the side that affects mains quality.
Electrostatic discharge
Contact and air discharge together with indirect discharge; the most frequently applied immunity test.
Radiated and conducted RF immunity
The device is exposed to a defined field strength and to an RF signal injected into the cable.
Mains-borne events
Electrical fast transients, surges, voltage dips and short interruptions.

Commonly confused in this field

An emission report alone does not complete an EMC file; immunity must be demonstrated as well.
An FCC report is not accepted in a CE file; the limits, measurement distances and set-ups are different.
The EMC Directive does not apply to vehicles; the UNECE R10 regime does. Specifications requiring both together should be reviewed.
The warning that a Class A device may cause interference in a residential environment is mandatory in the manual; market surveillance checks that this warning is present.
The test set-up is part of the report. If cable type, length or routing changes, the result changes; measurement must be made in the series-production configuration.
CISPR 22 and CISPR 13 have been withdrawn; their current counterparts are CISPR 32 and CISPR 35.

Which decisions these results support

CE declaration under the EMC Directive
The EMC part of radio equipment conformity
A UNECE R10 file for a vehicle component
Resolving field interference complaints and correcting the design
Assessing the EMC impact of a board or wiring-harness change

Related Tests

Frequently Asked Questions About CISPR 25

According to which standard is CISPR 25 made?

CISPR 25 is executed in scope CISPR 25, UNECE R10 and ISO 11452 (immunity side). The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.

Which products does CISPR 25 apply to?

Mainly applied to Electronic control units, Electric motors and drives, DC-DC converters and inverters, Lighting modules and Charger and OBC. Whether your product is included in the scope is determined by examining its technical specifications and intended use.

Under what conditions is CISPR 25 done?

The determining parameters are: radiant emission — Typically 150 kHz – 2.5 GHz; Divided by antenna type, Conducted emission — Voltage method (150 kHz – 108 MHz) and current probe method and limit class — Class 1 – 5; determined in customer specification. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.

What kind of sample is needed for CISPR 25?

Wire harness length and layout must comply with the standard, Load simulator and feeding arrangement must be documented and The worst-case operating mode must be determined. The number of samples is determined according to the product standard and the scope to be reported.

How long does CISPR 25 take?

It depends on the frequency range and number of operating modes; typically one to three business days. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.

What is the CISPR 25 result called "appropriate"?

The acceptance criterion is the emission limits of the selected limit class. As the class number increases, the boundaries become stricter.