Fundamentals of SiBar Thyristor Surge Protection Devices
SiBar thyristor surge protectors are
bidirectional silicon devices that fold back in
the presence of transient overvoltage faults.
When the breakover voltage of a SiBar device
is exceeded, the device switches from high to
low impedance to protect sensitive
downstream equipment from harmful voltage
surges. The device remains latched in a low-
impedance state until the current decreases
below the hold current, at which point the
device returns to its high-impedance state.
SiBar devices may be used in conjunction
with PolySwitch®resettable fuses in
telecommunications applications, including
network equipment, customer premise
equipment, and primary protectors. Proper
selection of both devices can provide reliable
and cost-effective resettable overvoltage and
overcurrent protection. These devices help
designers to meet worldwide
telecommunications standards and to lower
equipment-service and warranty costs.
* Superseded by UL 1950, 3rd Edition for new designs.
Note: For more information on PolySwitch resettable fuses for overcurrent protection, please contact your local Raychem representative or visit our Web site
(www.circuitprotection.com)
Typical applications
Problem/solution
Industry standards and customer
specifications require telecommunications
equipment designers to protect against the
harmful effects of power cross, power
induction, and lightning surges. These
hazards can travel through the network and
local loop, resulting in equipment damage and
loss of service.
A SiBar thyristor surge protector, either by
itself or properly coordinated with a
PolySwitch overcurrent device, will assist in
protecting against these faults, minimizing
equipment damage and improving customer
satisfaction.
Customer premise equipment (CPE)
SiBar devices have been designed to assist
customer premise equipment manufacturers
meet the stringent requirements of
FCC part 68, UL1459/UL1950 3rd Edition,
UL497A, and ITU-T Recommendation K.21.
Examples of customer premise equipment
include:
• PBX systems
• Key telephone systems
• Modems
• Phone sets
• POS equipment
• Surge strips with communication ports
Network equipment
SiBar devices have been designed to assist
network equipment manufacturers meet the
stringent requirements of Telcordia GR-1089,
ITU-T Recommendations K.17, K.20, and K.45.
Examples of network equipment include:
• Analog and digital linecards
• Base stations
• Meter monitoring systems
• Multiplex/pairgain systems
• Remote terminal units
• Repeaters
Customer premise equipment protected with
SiBar and PolySwitch devices
Network equipment protected with SiBar and
PolySwitch devices
SiBar thyristor surge protectors and PolySwitch resettable fuses are designed to work together to effectively protect telecommunications equipment
from transient overcurrent and overvoltage faults defined by regional agency specifications.
Specifications PolySwitch Resettable Fuse SiBar Surge Protector
ITU-T K.20 TR250, TS250, TSV250 TVB170SA, TVB200SA, TVB270SA
ITU-T K.21 TR250, TS250, TSV250 TVB170SA, TVB200SA, TVB270SA
ITU-T K.45 TR250, TS250, TSV250 TVB170SA, TVB200SA, TVB270SA
FCC Part 68 TR600-150, TS600-170 TVB270SA
UL 1459* TR600-150, TS600-170 TVB270SA
UL 1950 TR600-150, TS600-170 TVB270SA
Telcordia GR1089 TR600-160-RA, TS600-200-RA TVB170SC, TVB200SC, TVB270SC
Telcordia GR1089 Intrabuilding TR250, TS250, TSV250 TVB170SA, TVB200SA, TVB270SA