I am working with one of my friend's project. Who requested me to find out the appropriat circuit diagram for this.

The goal of this project is satisfying the following tasks:
1. Connect the loads to the PDB supply when supply is available on PDB.
2. When supply failure occur on PDB line, start up the standby 3 phase alternator automatically and switch the loads to the alternator.


I have given here the developed ladder diagram designed by me. I am using relay, magnetic contactor and timer for this propose. But one problem is that I noticed here, when power failure will occur, the timer will be no longer getting the supply. I am looking for any kind of help, recomandation, or even better practical circuit diagram for this project. I will be thankful if anyone can help me.

 

What's PDB.
Where do the contactors and relay get their supplies from.?

 

PDB stands for Power Development Board. PDB is government organisation that manage generation, transmission and distribution of electrical power.
These relays and contactors are getting thier supply from, parhaps, PDB. By the way, this is not for apply. It's just a collage demo project for change over switching.

 

What's PDB.
Where do the contactors and relay get their supplies from.?

PDB stands for Power Development Board. PDB is government organisation that manage generation, transmission and distribution of electrical power.
These relays and contactors are getting thier supply from, parhaps, PDB. By the way, this is not for apply. It's just a collage demo project for change over switching.