1. Marcello Piccolo Napoli Dec., 1997 1 The Babar IFR Low Voltage System Naples, 12/15/1997 Electronic review

2. Marcello Piccolo Napoli Dec., 1997 2 Requirements  The FEC’s for the IFR include  3200 boards to do discrimination, pulse shaping and address encoding. oThe FEC’s are located as close as possible to the pickup electrodes not to spoil with long cables the good time resolution of the RPC’s oFEC’s come in two flavors, as induction electrodes are on both sides of the RPC’s.  Power consumption is different by  20% : positive input FEC’s use more power than negative. oTwo voltages are needed : +7 and -5.2 V èTypical consumption are: +.31/-.12 neg.. Fec’s +.37/-.16 pos. Fec’s  Total power drawn:  W (+7), 2.5 KW(-5.2) oCorresponding currents : 1100 A (+7), 450 A (- 5.2)

3. Marcello Piccolo Napoli Dec., 1997 3 Design Philosophy oGiven the amount of current to be supplied, locate power modules relatively close to utilization. oUse a relatively high number of power modules so that (unlikely) failures would bring down a limited part of the IFR. oSelect a very reliable product (MTBF >40,000 h) oUse a connection scheme in which each board is independently attached to L.V.: most of the barrel boards in fact cannot be reached without opening BaBar …. and this is not even enough.

4. Marcello Piccolo Napoli Dec., 1997 4 Power supply selection oThe devices we have selected are produced (almost custom) by Power Control System: èModels chosen come in two types: 400W or 100W (output power). èThe MTBF quoted by the manufacturer is 80,000 h and 100,000 h respectively.  At full power  = 75% (see Tech data sheet) oOther features include èForced ventilation for the 400 W model è95 o C shut-off èTTL/CMOS ramp down/up capability èPrimary current limit @ 30 A for the 400 W model èLine regulation better than 1% èLoad regulation better than 1%. èCalibrated shunts to measure output currents.

5. Marcello Piccolo Napoli Dec., 1997 5 S-100-P Data Sheet

6. Marcello Piccolo Napoli Dec., 1997 6 S400-7 data sheet

7. Marcello Piccolo Napoli Dec., 1997 7 Power clusters oThe maximum number of boards to feed is : è1536 barrel è 864 backward end cap è924 forward end cap oThe spatial distribution of the boards forces the use of power cluster for each subsystem. oWe have planned 2 power clusters for the barrel on each (East and West) platform, and one power cluster on each half endcap. èThe barrel power clusters consist of two 6U crates (Barrel Supply Power Modules)which contain 3 7V/400W modules and one -5.2V/400W module. èThe end-caps power clusters consist of ; 1 6U crate containing two 7V/400W modules and three -5.2V/100 W modules (HPSM) and 1 3U crate containing 1 7V/400W module and 1 - 5.2/100W module. oThe total power capability installed is 9.6 KW @+7V and 3.2 KW @-5.2. The power margin is about 20%. oPower dissipation of the cluster: 800 W barrel 400W end-caps.

8. Marcello Piccolo Napoli Dec., 1997 8 The 6U barrel crate

9. Marcello Piccolo Napoli Dec., 1997 9 The End-cap 6U crate

10. Marcello Piccolo Napoli Dec., 1997 10 Boards power distribution oIt is highly desirable to have individual (dis)connect of the boards, even if each of them is fused on the two voltages ( and crow-bared on the +7).  Very reliable connection needed (  10,000 connections to do)  oUse faston connections for individual boards inside iron gaps. oBoards from the last three layers in the barrel and vertical strips in the end-caps are located in small crates on the outside of BaBar. oPower cables for the iron gap FEC’s go through the conduits used to extract signals, in separate compartments. Plenum rated cables (Belden parts # 83503) are used. o12 conduits on each end (+z and -z) carry the cables to the outside world in the barrel and three conduits are used for each half end-cap.

11. Marcello Piccolo Napoli Dec., 1997 11 Boards power distribution (cont.) In the barrel each conduit has a fan-in/fan-out device sitting on top of the  wire-ways 24 (12 on each end) of those distribution points have to be equipped. One distribution point power 48 iron gap Fec’s (layer 1-16) and one minicrate (layers 17,18 19). One sextant is serviced by 2 distribution points connected to DIFFERENT power modules. In the end-caps, each half door has three distribution points for the iron gap FEC’s. (Each of these has to feed 72 negative FEC’s). All the positive FEC’s in the end-caps are in minicrates, so individual connection for series of those are foreseen. Distribution points were designed so that a max. current between 20 and 25 A would be split in them: this figure sets the gage for the interconnecting wires.

12. Marcello Piccolo Napoli Dec., 1997 12 The single barrel conduit distribution box

13. Marcello Piccolo Napoli Dec., 1997 13 The power distribution on one end of the barrel (conceptual)

14. Marcello Piccolo Napoli Dec., 1997 14 The power distribution on one half the back end-cap (conceptual)

15. Marcello Piccolo Napoli Dec., 1997 15 The power distribution on one half the forw.end-cap (conceptual)

16. Marcello Piccolo Napoli Dec., 1997 16 Components inventory and purchasing

17. Marcello Piccolo Napoli Dec., 1997 17 Fast tour of components o3 conductor cable Plenum Belden parts # 83053 oFaston and faston blocks AMP parts # oMetal containers for faston blocks oConnection wires to the power modules: èAWG 2 10 m. power supply distrib. Box èAWG 10 5 m. distr. Box barrel minicrates èAWG 2 5 m. power supply end-caps minicrates oPower supply modules oCrates 6U and 3U eurocrate standard with slides oMonitoring cables èbuffer amplifiers to match GMB’s input range oFan unities 12 (one per crate) oSolid state relay to remotely turn on crates èDin Rail power supplies switches and cables (12) èInterface for software turn-on.

18. Marcello Piccolo Napoli Dec., 1997 18 Installation schedule oPower supply modules: è80% purchased; 70% at SLAC oCables: èFEC’s connection purchased ; harness in production at Naples. èSupplies-distributors on hand (SLAC store) oContact blocks: èpurchased, being delivered at SLAC (Anderson) oFaston èpurchased being delivered at SLAC (Anderson) oCrates èPurchased being delivered at Frascati èSome work to do on the to punch holes slots etc. ready by the 10th of January. oPrototype crate (BPSM) èready with all the cabling /monitoring before Christmas. Few BPSM ready at SLAC by end of January.

19. Marcello Piccolo Napoli Dec., 1997 19 Conclusions oThe low voltage system for the FEC’s is essentially designed; prototype is finished and production is ready to go. oIn spite of the standard type of requirements, practical design has presented few challenges mainly due to the sizable amount of power one has to produce and distribute. o Solutions have been chosen to maximize reliability and ruggedness of the plant. oWith our design we’ll be able to handle single boards connections from the outside of the detector. oReliability of the active parts are well above the limit we could have tested with the RPC quality controls runs during production.