HVR International Ltd products

The SR Series of Surge Resistors for PCB mounting are manufactured from a carefully selected mixture of clays, alumina and carbon. After blending, the material is pressed to the required shape and then fired, in a controlled atmosphere, at high temperature. This sintering process produces a Ceramic Carbon Resistor which is 100% active material and therefore of minimum size. The SR Series feature Gold Plated Brass spring pin terminations for ease of assembly into Printed Circuit Boards (PCB's). Dielectric withstand and mechanical robustness are enhanced by the UL94 V-0 approved epoxy resin coating. Compact in size and with high surge energy rating, the modular SR Series is designed to provide the optimum solution to many Power Electronics applications; notably soft starting the DC link capacitors in Switch Mode Power Supplies. Inherently non-inductive and capable of withstanding transient high voltage impulses, the SR Series is similarly effective with respect to overvoltage protection and crowbar discharge applications.

The RT / RL series of non inductive, ceramic composite resistors are ideal for circuitry associated with surges, high peak power or high energy, replacing carbon composition resistors which can be difficult to source. They offer enhanced performance in high voltage power supplies, R-C snubber circuits and inrush limiters. In pulsed applications, these compact resistors distribute the energy uniformly throughout their structure, resulting in low thermal stress. The result is increased reliability, and in many cases reduced size, compared to wire or film types. The solvent-resistant epoxy coating allows operation in almost any environment, and the choice of axial or radial lead construction offers convenient use.

Ceramic Carbon Resistors can be offered separately, in matched sets with respect to Resistance Value, or pre-assembled for ease of installation. Resistor Discs can also be supplied in stacks, marked and numbered for optimum flatness and parallelism. It is generally recommended that HVR carry out any assembly work since using our specialised jigs, we will ensure that Resistor Discs are aligned correctly and that the appropriate mounting force is applied. This is important not only for mechanical reliability, but in minimising the risk of electrical activity between successive resistor discs and the disc / terminal interface. Wherever possible, a Resistor Assembly will be designed using standard components, thus enabling us to offer the most cost effective solution.