What Is a Timer (T) Relay? Coil (2·7) and Timed Contact (8·6·5)
A timer belongs to the same relay family as the 8-pin relay and the EOCR — "coil energizes, contacts flip." The one difference is when they flip: not the instant the coil energizes, but after a delay you set in advance. The Korean term is 한시(限時) 동작 — "time-limited" operation.
Coil (2 · 7) — same socket, same promise as the 8-pin relay
- 2 · 7 (coil) — put a voltage across these two and the timer energizes; the internal count starts at that instant.
- The moment the coil drops — the count resets to zero immediately and the contacts snap back to rest (instantaneous return). Break and re-energize and the count starts over from zero.
The coil position (2·7) and pin layout are 100 % identical to the 8-pin relay, so the two share the same socket.
Timed contact (8 COM · 6 timed-NO · 5 timed-NC) — flips only after the delay
- 8 (COM) — the timed contact's common pole; one leg of the fused supply usually lands here.
- 6 (timed-NO / delayed-ON) — open at rest and during the count, closes when the delay expires. The pin behind "turn this on N seconds after pressing."
- 5 (timed-NC / delayed-OFF) — closed at rest and during the count, opens when the delay expires. The pin behind "keep on for N seconds, then cut automatically."
Both share one common (pin 8) — the same "one coil moves the whole set together" pattern as the relay.
See it work
This canvas's timer is set to 3 seconds.
Press PB1 and the coil (2·7) energizes immediately, but the motor and GL stay dark — pin 6 is still open, so current can't reach the MC coil behind it. The instant 3 s elapses, 8-6 closes, the MC coil energizes, the motor spins, and GL lights.
Almost every exam circuit uses an on-delay (TON) timer — it counts from the instant the coil turns on. An off-delay (TOFF), which counts from the instant power turns off, is a separate variant you tell apart by the triangle direction in its symbol.
Next
That completes the tour of every core part that goes into the panel. Next come the rules of *placing* those parts on the board without getting disqualified — see Control-panel layout.
Try it yourself
Hold PB1 and watch the motor spin up 3 seconds later in the Korean Electrician practical simulator →