Toshiba GR200 Series Instruction Manual page 527

Star mode
(ii)
When a three-terminal line application is applied, the star mode is selected. As seen from
Figure 2.36-10, the IED is connected with the others with a bidirectional channel, provided
two or more IEDs exist.
When switching of channel route is occurred, and the fluctuation of channel delay is
appeared, the IED corrects the channel delay automatically. As a result, the switching does
not influence the synchronized sampling, and the IED can take sending and receiving data as
usual. When a difference exists on the communication route, the difference of channel delay
should be set and calibrated.
Communication setup
2.36.4
Setting of Channel exchange
(i)
In the case of the two-terminal line arrangement, the communication is interlinked with
channel#1 and channel#2, as shown in Figure 2.36-1. In the case of three-terminal line
agreement, the IED at terminal G is linked with the channel#1 and the channel#2 as
shown in Figure 2.36-3. Suppose the IEDs have the normal linkages, the user should set
Off for scheme switch [CHCON]. However, the user should set On for the scheme switch
[CHCON] when the change of the channels is required.
Setting in multiplexer
(ii)
Scheme switches are provided so that the IED is able to connect with the multiplexer
(MUX) properly.
•
Scheme switches [CH*_T.SFT] are used to synchronize the IED with MUX by
shifting the send signal by a half-bit provided the IED is placed far from the MUX.
Suppose electrical interface ITU-T G.703-1.2.3 is applied and the distance (cable
length from relay to multiplexer) is 300m or more, you should place a set of On
Bus G
IED G
Bus R
Figure 2.36-10 Star communication mode
- 504 -
Bus H
IED H
IED R
6F2S1914 (0.49)
GRL200 (Soft 033 & 037)