The fundamental philosophy used in the development of THOR SYSTEMS’ products is a hybrid surge protection design comprised of high power Silicon Avalanche Diodes (SADs), Thermally Protected Metal Oxide Varistors (TpMOVs), and Filter Capacitors.
SADs are the closest to an ideal suppression element providing the fastest response time and the most effective voltage levels of any suppression elements. The disadvantages of using SADs only are limited surge current levels and higher costs as compared with other suppression elements.
TpMOVs, “fail-safe devices” with integrated thermal and dielectric (arc shield) protection, are composed of a disconnecting apparatus that monitors the status of the metal oxide disks. The disconnection also provides a physical indicator and remote indication provided by an integral N.O. micro-switch. Together, SADs and TpMOVs offer a surge protector package combining very fast response with high energy handling capabilities and increased product longevity. THOR SYSTEMS invested considerable time and effort coordinating both suppression elements to maximize these combined features.
The third element of our hybrid design is the Filter Capacitor, which is used for EMI/RFI noise suppression and works between the zero (0) point on the waveform and the turn-on level of the TpMOVs and SADs. This capacitor resists voltage changes by using its energy storage capability.
THOR SYSTEMS selected specific metallized polypropylene capacitors that can operate at higher AC voltages and have self-healing characteristics when exposed to surge events. The combination of these three elements offers the optimum in surge protection.
The final design philosophy incorporated by THOR SYSTEMS is the use of fewer large TpMOVs. While MOVs are the most accepted suppression element in use today, there are definite differences in larger MOVs versus multiple smaller ganged/paralleled MOVs. The improper sharing of current between multiple devices can cause a single device to operate beyond its limits, triggering individual and cascading component failures. Also, large multiples of paralleled MOVs require precise matching procedures and can necessitate the de-rating of their surge current and energy rating up to 20%. (For example, to obtain 50kA rating for an 8×20µs transient, eight  20mm MOVs would be required to provide the same surge current rating as a 34mm TpMOV.) The larger TpMOVs provide 100 times greater pulse life promoting maximum system reliability. This unique hybrid design provides THOR SYSTEMS the ability to deliver full-rated surge protection capacity for each mode of protection.
We have also developed StakTraksTM a unique, inventive design concept, which uses combinations of double-sided printed circuit boards having multiple parallel surge paths and solid copper buss works comprised of C1100 buss bars and tellurium C1450 hex rods. Heavy copper parallel printed circuit board traces interconnect the individual suppression elements of the hybrid arrays, as well as all individual suppression modes, providing a concise, low impedance surge and lightning protection design with extremely fast reaction times. The StakTraks™ design dissipates and diverts transient overvoltage away from sensitive electronic equipment. The hybrid design utilizing the StakTraks™ concept is used throughout THOR SYSTEMS’ TSr (field replaceable) and TSn (non-field replaceable) product offerings.