Brick Wall Series Mode AC Surge Suppressors/Powerline Filters 

New Performance Standards

The following graphic represents a comparison of standard oscilloscope traces. The MOV based protector (left) and a Brick Wall Surge Filter (right) are both experiencing a 1200V, 450A surge. Scope Traces of Brickwall Surge Protection


The heart of our units is the inductor. This is a passive component that is in series. It does not
have to 'turn- on' and it represents the only path the surge current can take to get to the load. It
reacts instantaneously. Almost all other surge protection devices are in parallel. After a certain
voltage threshold is reached the shunt elements create a short circuit diverting the surge current
away from the load. In effect it is a switching device. Any switch, no matter how good, is going to
take time to go from an opened to a closed position.


MOVís are preset to clamp at certain voltage thresholds (usually around 220V). The
manufacturers walk a fine line here because too low a level and the MOV turns on more and
wears out sooner. Too high a level and more unwanted current has access to the load. Even
more importantly, marketing rhetoric is sacrificed. Our Series Mode device has active tracking; a
180Ķf electrolytic capacitor constantly tracks the sinewave peak, whatever the powerline voltage.
Any rise above this reference level is immediately clamped to this level.


Voltage that gets by a surge suppression device to the load is called the let through voltage. The
lower the let through voltage the better. The above oscilloscope trace of a Brick Wall product
shows a let-through voltage of 192V for a 1200V transient. That represents an additional 20V
above the sinewave peak (the sinewave peak is normally 172V). UL endurance tested the
product with one thousand 6000V surges and the let through never exceeded 290V (290V is the
approximate let through voltage an MOV-based device would experience at 1200V). We believe
this represents the lowest let through voltage in the industry.


Slew Rate is the rate of change of voltage in volts per microsecond. The faster the slew rate the
more readily the overvoltage will couple to nearby datalines. Notice the ascending slew rates of
the photographed oscilloscope traces. This is representative of the voltage that 'hits' the load
before clamping. A quick rise such as this can represent quite a 'jolt' to the equipment. The trace
of our unit shows a negligible slew rate. Again, we believe this represents a new industry

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