ERICO TSG Series Surge Reduction Filters (TSG-RSF) - Manual (Page 5)

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Introduction
Both issues have been addressed with the
CRITEC
® TSG, a spark gap surge diverter
incorporating a triggering device which
enables the TSG to operate on much lower
voltages than was previously possible.
Additionally, the TSG is able to extinguish the
spark and return to the peak mains voltage
as soon as the transient event has passed,
thereby greatly improving follow-current
performance.
These considerable technological advances
mean that the TSG can be utilised as the
primary shunt diverter within the new SRF,
exploiting the performance benefits of spark
gap diverters.
Incorporating TSG technology into a surge
reduction filter has allowed a fundamental
breakthrough in the overall design of the
filter. Ferrite cored inductors, which are
much smaller than non-saturating air-cored
inductors required in MOV based surge
reduction filters have been used in the
CRITEC SRF.
The use of ferrite-cored inductors is possible
because the let-through voltage from a TSG
remains high for only a few microseconds
(μs). In comparison, the let-through voltage
from a MOV based device remains at
anywhere between 600V and 1000V for the
duration of the surge. This time can range
from 30μs to 400μs and above for longer
tail pulses and determines how much energy
the inductor has to store before reaching
saturation and becoming ineffective.
The combination of TSG and TD technology
provides the benefits of high surge capability,
low let through voltage and considerably
reduced dv/dt. This applies to both surge
performance and over-voltage withstand from
short and long duration high-energy surges.
TD technology has been developed
specifically for abnormal over-voltage
conditions that may occur on sites with
poor voltage regulation, or due to wiring or
distribution faults. TD and TSG technologies
feature an extremely high over-voltage
withstand. This eliminates heat build up that
can occur with standard technologies when
the protection devices start to clamp on the
peak of each abnormal mains cycle.
Traditional MOV technology is not suitable in
applications where sustained over-voltage
conditions can be experienced. The range of
CRITEC TSG-SRFs, with a higher abnormal
over-voltage withstand, are preferred in these
environments.
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