FUSE RESISTORS

Last Updated on Monday, 28 November 2011 08:43 Written by Frieda Monday, 28 November 2011 08:43

A fusing resistor is designed to protect a circuit against damage as a result of current or voltage overload.  The resistor limits current flow and protects the circuit by opening (stopping current flow) when current levels exceeds its fuse characteristic design limits. The resistor serves the dual functions of a fuse and a resistor to limit the current.

Riedon fusible resistors are normally wire-wound resistor designed to open at power levels specified by the application.  These resistors must be specially analyzed and designed for a customer application in order to assure that the fuse opens under the right conditions and within the time duration specified by the application.

Please contact Riedon to discuss your fusing applications.  We would be happy to work with you to develop a product for your requirements.  Call us to get more information.

Why Buy Matched Set Resistors?

Last Updated on Friday, 18 March 2011 12:09 Written by Frieda Wednesday, 16 March 2011 04:11

Matched resistors are a set of resistors where an additional parameter(s) is given to link the resistors. For example, resistor ‘A’ and resistor ‘B’ have

matched resistors

a resistance of 100Ω, a tolerance of 5%, and a TCR of 25 + 5 ppm. You may add additional parameters to this set calling for the pair to be no more than 1% apart and also within 5ppm of each other. If resistor ‘A’ is 95Ω and resistor ‘B’ is 105Ω, both of which are within their individual tolerances, then these resistors would not be matched since they deviate more than 1% in comparison to each other. Conversely if resistor ‘A’ has a ppm of 20 while resistor ‘B’ has a ppm of 25, then the TCR of these resistors would be matched since they meet the requirement of being no more than 5ppm apart from each other. It is important to consider TCR as well due to the variation in resistance as the components heat up, which may flaw your design. This is not limited to only a pair of resistors and can be applied to as many as your application needs.

There are applications

where choosing matched resistors is sometimes necessary and advantageous financially. Take for example a simple voltage divider. If precision in the output voltage is important in your design then choosing a set of matched resistors is crucial. You may be wondering why you wouldn’t select some precision resistors for your design instead and you wouldn’t be wrong in assuming so. However in applications where the ratio of the resistors is more important thanthe precision of the resistors, it would cost less to purchase a set of resistors with a tolerance of 1% matched to 0.1% than to produce a set of resistors with a tolerance of 0.1%.

Some industries of interest are oil and gas in their use of down-hole instruments and various military applications and scale instrumentation. If you are unsure whether or not you are able to apply matched resistors in your application, please do not hesitate to ask Riedon. With over x years of experience in producing custom resistors, we are confident in our ability to assist you in your design

What are Wirewound Resistors?

Last Updated on Monday, 12 July 2010 03:53 Written by riedon Monday, 12 July 2010 03:50

Resistors are commonly found elements in electrical networks and circuits. These components are used to control electric current flow within electrical parts and circuit boards. One of the most common types of resistors is known as the wirewound resistor. Wirewound resistors are produced by winding metal wire around a plastic, fiberglass or ceramic core. Typically, this metal wire is comprised of nichromea nickel-chromium wire.

Optimized circuit designs often include wirewound resistors where precision is important. Wirewound resistors have tight resistance tolerances and are typically very stable. Since these resistor types can maintain their precision over time, they are extremely popular in electrical components. They are comprised of very stable materials and are very reliable and rugged. Modern circuits typically use wirewound resistors for this reason.