What does this ladder logic schematic showing a coil in parallel(?) with a contact mean?

Question

I am confused on this schematic drawing and understanding what it means when I see the T1 coil in parallel (I'm not even sure) with the PR1 contact?

Does that mean they are logic "OR"ed together or something else entirely?

Yes, T1 OR PR1, Relay PR1 (6) closes contacts PR1 (8) to take Timer? T1 out of the circuit. — StainlessSteelRat, Apr 28 '21 at 21:28
note that PR1 contacts connect to the body of T1 not to the supply lines of T1 — Jasen Слава Україні, Apr 28 '21 at 23:53

score 1 · Answer 1 · answered Apr 28 '21 at 22:13

The PR1 contact should not truly be connected in parallel with the T1 coil:

If it were, energizing coil PR1 (e.g. by pressing the "FIRE" button) would short Line and Neutral and blow the fuse.

Most likely device TR is not a typical relay (or even a typical timer relay). It's always connected to L and N, so always energized.

Most likely the two extra terminals on TR control it's behavior. Maybe it is a reset or start input to initiate a timer interval?

Transistor · Answer 2 · 2021-04-28T22:58:55.847

1

Pressing FIRE energises relay PR1.
T1 (Timer 1) is always powered. A contact of PR1 starts the timing function. Note that the contract wires do not connect with the L1 and N wires so it's not in parallel with the timer"coil".
When the preset time has expired T1's contact closes and turns on TRC1, etc.
Releasing the FIRE button releases PR1, resetting the timer and opening contact T1.

edited Apr 28 '21 at 22:58

answered Apr 28 '21 at 22:40

Transistor

2 Answers2