The use of IRIG-B Time code for accurate time synchronisation of multiple devices in the Power Generation Industry

Photo-Sonics International Ltd. proposes a system for time synchronisation of relays and other devices in the power generation industry.  The system consists of a GPS derived master clock system (ITS 400-D), which generates an IRIG-B time code output and a 20-channel distribution amplifier (ITS 490-D20), which distributes this time code to the required number of devices. With the implementation of just one master clock and six distribution amplifiers up to 600 devices can be accurately time synchronised.  


GPS Derived

The proposed system permits the supplied GPS antenna to be located up to 100m away from the master clock system, this offers freedom to accurately locate the antenna.  The system is time directed so once a fix is obtained (requires 3-4 satellites) then only one satellite is require to maintain timing accuracy <100nsec.  The GPS signal can be lost for over one week and timing accuracy will be maintained.



The system generates and distributes demodulated IRIG-B002 time code.  This is delivered by high current, short circuit protected devices capable of driving up to 150 metres of shielded twisted pair cables.  Each output can synchronise up to 5 devices in a “daisy chain” fashion only requiring a 120W resistive termination at the end of each line, thus permitting the use of the existing cable trays for routing of the IRIG-B signal to each device. In addition the output of the distribution amplifier is a standard terminal strip just like the input terminal strip of a protection relay.  Therefore, this system requires no special connectors, terminations or tools.


ITS400-D ITS490-20D
ITS 400-D

Twelve channel GPS receiver
IRIG-B time code generator
Front Panel Time/Status Display
Six Demodulated IRIG-B serial outputs
Parallell Status/Control Port and RS-232 Data Port
ITS 490-20D

One 75Ω BNC Demodulated IRIG-B code input
Twenty buffered TTL demodulated IRIG-B Tiime Code outputs
Terminal board interface for twisted pairs
Each channel can drive up to 5 2KΩ loads
Each channel must be terminated with 120Ω at the end off the twisted pair


The diagram below (click to enlarge) shows the typical connectivity of the system.  The master clock system (ITS 400-D) has six IRIG-B002 outputs, if all outputs are connected to a distribution amplifier (ITS 490-D20) which has 20 IRIG-B outputs then up to 600 devices can be synchronised.


Overall Connectivity


In summary, the system offers a low cost, easy to install method of time synchronising large amounts of devices in power generation applications.  Links to Product datasheets are provided on the right and if you require further assistance or pricing please Click Here to contact a member of our sales team.


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