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CABLE PREPARATION AND LAYING
Although technically there is no limitation but as a matter of symmetry E&M
Trunks will be accommodated in TU1. One 24 pair cable will be required for each
E&M card. The entry of these cables are through the holes provided at the top of
TU1.
For each DTU, one 8 pair digital trunk cable will be sufficient. For TWT trunks 64
pair cables are used in other than TU1.
BM (Digital trunks only)
In this case only one cable of 8 pairs will be laid for 4 Digital Trunks in each TU.
Wiring Details for Lines & Trunk BM on MDF
MDF for Multimodule exchange is supplied in multiple of 5 verticals. For exchanges
upto 2K lines 5 vertical MDF is enough. For higher capacity exchanges 10 to 20
vertical MDFs are supplied. In a 5 vertical MDF, first 4 verticals can be used for
terminating 2 Line BMs and 2 LMs. The 5th vertical can be used for Trunk BM.
Each vertical of the MDF has 10 backmount frames. As shown in fig. 10.52, vertical
V1, backmount frame V1/1 and V1/2 accommodates TU-1 of BM1. Similarly TU-2,
TU-3 and TU-4 are terminated upto V1/8. Then TU-1 of LM-1 of BM-1 is terminated
on V1/9 & V1/10. Rest of the TUs of LM-1 and LM2 are terminated on vertical V2,
V3, V4/1, V4/2 of vertical V4. Now the last vertical V5 can accommodate Trunk BM
(say BM5) if only 5 verticals are available. Fig. 10.52 explains the case of 7.5K line
exchange termination on 15 verticals. E&M Trunks of TU-1 in BM5 will be
terminated on V13/1 to V13/7. Each backmount frame can accommodate 2 EMF
cards. Detail of termination is given in Fig. 10.51 (b). A maximum of 14 EMF cards
can be there in TU-1 which will absorb 7 backmount frames of V13. Backmount
frame V13/8 & V13/9 can be allotted to TU-3. TU-3 has only TWT trunks. TWT
trunks of TU4 can be terminated on V13/10 for slots 3 to 10. For this purpose 64
pair cable can be used as in the case of TU- 3 whereas for slots 17 to 24, 24 pair
cable can be used. So fair 24 pair cables will be used for slots 17 to 24. These cables
can be terminated on the 2 LSA plus modules free on each backmount of TU-1 i.e.
V13/1 to V13/7. This is shown in Fig. 10.51 (b). So in this fashion one vertical can
accommodate one Trunk BM. Similarly V14 and V15 can be used for other Trunk
BMs.
Lineside Details
100 Pair switchboard cable can be used for termination on the line side backmount
frames, either from bottom to top or top to bottom. The underground cable can also
be terminated directly on the backmount frames. But care should be taken that the
underground cables is routed along the vertical from bottom to top. It should not be
laid from top to bottom, otherwise jelly will keep on dropping from cable. The 100
pair cable termination on a backmount frame of 10x10 is explained in Fig. 10.50.
The cable is to be terminated on the top side of the disconnection modules and
bottom side is to be used for jumpering. The first pair is to be terminated on the left
hand side of the bottom disconnection module. Terminations should grow from left
INSTALLATION MANUAL
305
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