I know the basic functioning of star delta motor starter configuration but kind of stuck on my current project which uses old L&T starter panel. I can't figure out the terminals like A1, A2 (coil power terminals), NO (used with push start the coil) etc. The panel has two push buttons

Green >> mechanically presses the starter stick

Red >> mechanically presses the stop stick

I am attaching pictures of panel, please help me figuring out the parts used and terminals. I tried searching on internet but can't get much details of these kind of contactors.

Edit: Sticks marked in last photo might be opposite

Front View Side view Front View Marked

  • \$\begingroup\$ That is a very sketchy install! Power that down, clean it out and properly seal the enterances! \$\endgroup\$
    – K H
    Commented Apr 7, 2021 at 9:43
  • \$\begingroup\$ Yes I see, actually not mine. One of my client has this system installed. Anyways I'll suggest them to clean it up and well seal it. \$\endgroup\$
    – Rishabh
    Commented Apr 7, 2021 at 10:05
  • \$\begingroup\$ tghe small terminals undeneath you starter stick/ stopper stick labels look like the start/stop coil look like coil on the left and contacts on the right. \$\endgroup\$ Commented Apr 7, 2021 at 11:14
  • \$\begingroup\$ If you cannot get information on the contactor terminals or find any markings on the part, the only thing to do is to trace the circuit out on paper and it should become very obvious. They are universal circuits and relatively simple as far as control circuits go. And keep the power off when doing so as these old components have lots of bare terminals. \$\endgroup\$
    – David777
    Commented Apr 7, 2021 at 12:29
  • \$\begingroup\$ The plastic boxes on the right look like more relay modules. It's possible that the module on the left is to connect/disconnect one side of the coils and the modules on the right reconnect the other ends of the coils between wye and delta, although I would expect that to be done with a single break before make relay for safety reasons. \$\endgroup\$
    – K H
    Commented Apr 8, 2021 at 5:30


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