Noise suppression resistors are wirewound resistors that are especially designed to reduce radio frequency interference (RFI) caused by high electrical voltage discharges generated by automotive ignition systems.
The resistor element is a resistive wire, which is wound in a single layer on a fibreglass or ceramic core. Metallic caps, electrodes and/or axial wire terminals are fixed to the ends of the resistive core to assure a good mechanical and electrical contact. A coating protects the resistive element against moisture, mechanical shock and is able to withstand high temperatures These products can be moulded with epoxy resin, thermoplastic or thermo set plastic materials.
RFI reduction method
As example, automotive ignition systems produce high voltage pulses and these pulses make the sparks that ignite the mixture air/gasoline in the combustion chamber. These pulses have a very rapid current change that generates an electromagnetic field around the ignition system. In addition pulses of current at the spark plug ionises atoms that during the de-ionisation process releases a wide range of radio waves. These waves with random frequencies generate the radio frequency interference (RFI) and disturb many electronic devices like engine management systems, radio/TV broadcasting and communication systems.
According to international legislation, these disturbances must be reduced to acceptable levels. One of the best solutions to minimise this noise interference is to introduce in the ignition system a noise suppressor resistor that can be placed in the rotor of the distributor, at the ends of spark plug cables, or fully integrated in the new ignition systems technologies such as the pencil coil.
NSR parameters
A noise suppression resistor (NSR) is a special wire wound resistor where the ohmic value (R), along with the self inductance (L), gives its frequency response behaviour, changing the impedance level (Z) with the change of the frequency. This impedance is responsible for damping the RFI or noise suppression. The main parameters to define a NSR are the ohmic value/tolerance and the self-inductance variables such as number of windings diameter and length of the resistive core. The final design for these products depends on the application and can be developed under request.
Typical characteristics available are: resistance, 1 kΩ to 15 kΩ; resistance tolerances, ±10%, ±15%, ±20%; working voltage, 25 kV to 40 kV; inductance level (2 MHz), 5 µH to 72 µH; operating temperature, -40 to 200°C.
DC-link capacitors with ultra-low inductance Electrocomp
Passive Components
TDK Corporation recently released its new series of MKP DC high-frequency film capacitors, a high-performance DC link capacitor platform for next-generation SiC-based power electronics.
Read more...EMC limits and levels Altron Arrow
Editor's Choice Circuit & System Protection
As soon as electronics and electrical systems started interfering with each other, the world had to come to some consensus. Considering physics is universal and does not care about what country electrical/electronic products are used in, it should be the same everywhere, right? It is nearly there, but not quite.
Read more...Non-contact linear position sensor Electrocomp
Test & Measurement
The Vishay 40 LHE Linear Position Sensor, designed for industrial motion control and automation, delivers robust, non-contact measurement performance using Hall effect technology.
Read more...Five signs your storage is holding you back
Infrastructure Surveillance
In the drive for business growth, organisations across South Africa are investing heavily in talent, applications, and strategy. Yet the foundational technology that underpins every digital interaction - data storage - is often overlooked.
Read more...Dahua expands wireless 4G security monitoring
Products & Solutions Surveillance Smart Home Automation
Dahua Technology has launched a new wireless 4G security camera under its WITHS series, designed to deliver simplified deployment, continuous monitoring, and dependable performance in remote and power-limited environments.
Read more...Smart port monitoring and automated container tracking LD Africa
AI & Data Analytics Surveillance Logistics (Industry)
A leading shipping port set out to improve visibility, security, and operational efficiency across its site, turning to an advanced monitoring solution powered by Axxon PSIM.
Read more...Safety relay for explosive areas IOT Electronics
Circuit & System Protection
Phoenix Contact has expanded its safety portfolio with the new PSR-MC35-EXI safety relay module, specifically engineered for use in potentially explosive environments.
Read more...Compact 1250 V choke solution Electrocomp
Passive Components
TDK Corporation has introduced a new high-voltage common-mode choke series designed to support more compact and efficient 1250 V DC converter architectures in next-generation power electronics.
Read more...Clearing the Static: Ensuring effective ESD control Actum
Circuit & System Protection
To maintain reliable electrostatic discharge control, regular testing and accurate measurement are essential, with grounding products and ESD testing equipment being vital.
While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.
printer friendly version