DESCRIPTION:
Traditionally, surge suppression circuits have relied solely on components such as metal oxide varistors, silicone avalanche diodes, or active circuits with transistor devices (SCR's). These robust components are designed to withstand the impact of an electrical surge or spike, and though they can do a credible job of clamping the rated voltage for which they have been designed, they have minimal immunity from large sustained electrical forces and can fail when tasked when presented with the challenge of a catastrophic surge.

Furman's SMP circuit employs a hybrid design utilizing a non-sacrificial, multiple-stage inductance circuit of low-loss series inductors, DC rectifiers, and high voltage shunt capacitors to absorb the vast majority of energy in caused by a surge or spike, as well as a high-current MOV and thermal-fused varistor to reduce the remaining energy to a non-damaging level. With this topology, the SMP circuit is ensuring it's own protection, while passing very little excess voltage to connected equipment - even when faced with a catastrophic surge. The circuit's measured clamping voltage is 188 Vpk (this is equivalent to 133 Volts RMS, which is only 11% above an optimal 120VAC line) at 6000V/3000A input. For comparison, competing professional, non-sacrifical circuits have clamping voltages that we have measured in excess of 400 Vpk.