Circuit & System Protection


Resettable fuses for telecom line protection

2 November 2005 Circuit & System Protection

Wickmann offers an extensive line of resettable and blow-type overcurrent protectors for telecommunications and networking equipment. The new radial-leaded Polymer Polyfuse HVR250 and HVR600 Series are optimised to provide overcurrent protection for applications that must pass Telcordia GR-1089, UL 60950, and EIA-IS-968 (formerly FCC Pt.68) requirements.

The HVR250 and HVR600 Series are designed to withstand a maximum of 250 V a.c. and 600 V a.c. Power Cross condition and to operate continuously at up to 60 V d.c. The devices are available in sorted resistance ranges, narrow resistance bin variances, and pre-tripped for better line balance performance and further noise reduction. The HVR250 Series is offered from 80 mA through 180 mA and HVR600 Series is offered with 150 mA and 160 mA hold currents.

The Polymer Polyfuse is actually a positive polymeric temperature coefficient (PPTC) device consisting of conductive carbon black particles. Under normal operating conditions, strings of carbon particles conduct current while exhibiting a very low internal resistance. When trip or fault current is exceeded, the particle strings break up and disburse randomly, which raises the internal component resistance by several orders of magnitude. This rapid increase in resistance limits current flow to nearly zero, effectively protecting the downstream circuitry. When the fault subsides or power is removed, the Polyfuse cools and resets its state.



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Clearing the Static: The importance of ESD audits
Actum Circuit & System Protection
An ESD audit is the first step in establishing an effective static control programme in the workplace, and will help identify vulnerable areas and potentially hazardous static zones that require improvement.

Read more...
Die-cast enclosures in non-rectangular formats
Communica Enclosures, Racks, Cabinets & Panel Products
These models from Hammond Manufacturing, the 1590TRP and 1590STP, provide additional flexibility for product designers who require strong aluminium enclosures, but want alternatives to the traditional rectangular form factor.

Read more...
EMI shielding materials application guide
Circuit & System Protection
TE Connectivity’s shielding solutions include electrically conductive elastomers, gaskets, knitted wire mesh, oriented wire, EMI shielding ventilation panels, shielded window, cable shielding and shielding components.

Read more...
Clearing the Static: ESD containers and packaging
Actum Circuit & System Protection
         Vacuum forming ESD Electronic components can be damaged by electrostatic discharges. To protect against such damage, electronic assembly parts are often transported or stored in vacuum formed component ...

Read more...
Electrostatic discharge chairs
Actum Circuit & System Protection
An ESD chair forms an integral part of grounding within the electrostatic discharge protected area to prevent potential damage to products.

Read more...
Conductive ESD footwear
Actum Circuit & System Protection
Conductive ESD footwear is used in conjunction with other grounding devices, such as a wrist strap, cord, and ESD surface mats, to provide a continuous path to ground.

Read more...
Clearing the Static: The importance of cleaning in ESD control
Actum Circuit & System Protection
To prevent Electrostatic Discharge (ESD) damage to sensitive electronic assemblies and components, all production, handling, packaging, and storage must take place in an ESD-protected environment.

Read more...
Clearing the Static: Staying grounded
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.

Read more...
Smarter protection without disruption
NewElec Pretoria Circuit & System Protection
Designed for operations still running without integrated automation, NewElec’s retrofit-friendly systems let you upgrade performance and safety without overhauling your entire network.

Read more...
Circuit breaker for reliable, compliant protection
RS South Africa Circuit & System Protection
Legrand’s low-voltage power distribution portfolio encompasses the DX3 range of miniature circuit breakers, designed to deliver dependable protection in residential, commercial and industrial installations.

Read more...









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.




© Technews Publishing (Pty) Ltd | All Rights Reserved