power distribution core


Thread Starter


As we know that <PD> core gets a.c as well as d.c power, in our plant ,the output of source selector provides 125 vdc to <pd> core, so when it is getting 125 vdc then what is the role of DACA which is also a.c to d.c converter , as far as i know DACA gets a.c power from the <pd> steps up and rectified in to d.c power and gives it back to the <pd> core, but when <pd> core is already getting d.c power from the output of source selector then what could be the reason of installing DACA???

Please answer this question as i am a new user here
and would like to request CSA and other users to help me answer this ambiguity...

Process Value

The Power distribution module has three sources so as to provide redundancy. This is how the setup works.

1. Three power sources are first brought to the PDM board. In the PDB the input is received in TB1 in the following manner.
a. 125V DC -- TB1 (2-3)
b. 115/230V ac -- TB1 (6-7)
c. 115/230V ac -- TB1 (10-11)

The input is filtered in the power filters before it is routed to the PDB.

2. The AC is then routed to the DACA through JZ2 and JZ3 in the PDM board. before the DACA the cable from the PDM carrying the ac must be plugged into JTX1 if the voltage is 115V ac or JTX2 if the voltage is 230V ac. This is for the transformer selection.

3. The DC output from the DACA is then again routed back to the PDM board through JZ2 and JZ3.This DC power is diode coupled to the main DC supply forming a redundant power source. This redundant power is then routed to the VME racks and the terminal boards.

Hope this clears the doubts regarding the power distribution in Mark VI. for further clarification read Mark VI manual volume II (GEH-6421_VOl_II). this contains necessary diagrams and the further detailed explanation.
I have two questions concerning this ssue, please:

1.- Can MVI work only with the DC supply? I mean, could it work if I threw away both DACAs?

2.- Do you know where can I find the pinout of the DACA connectors?