Compressor Auto Star Delta Wiring

Star (Y) Starting: Connect motor windings in star → lower voltage per winding → reduced starting current (~33%).

Delta Running: After start, reconfigure to delta → full power running.

Auto Timer / Control: A timer or control logic switches between star and delta.

⚙️ Components You’ll Need
Component Purpose
MCCB / MCB Main circuit protection
Contactor K1 (Main) Supplies power to motor
Contactor K2 (Star) Connects motor in star
Contactor K3 (Delta) Connects motor in delta
Timer (T) Controls star → delta transition delay
Overload Relay (OL) Protects motor from overcurrent
Control Supply 24V/110V/230V depending on controls
Push Buttons START / STOP
Star Connection

Star Contactor (K2) links U2, V2, W2 together.

This puts motor in Y (star) mode at start.

Delta Connection

Delta Contactor (K3) connects:

U2 to W1

V2 to U1

W2 to V1

Gives full line voltage to each winding.

📍 Typical Control Circuit (Logic)

This is how the control logic operates:
Sequence

Press START

K1 and K2 energize → motor starts in Star

Timer T counts (1–3 sec)

K2 drops out (Star off)

K3 energizes

Motor now in Delta

🛠 Step-by-Step Wiring (Control)

Power Supply

Use control transformer if needed (e.g., 415V → 230V).

STOP Button

Place in series with control supply.

START Button

Normally open → triggers K1.

Main Contactor (K1)

Seals in via its own NO auxiliary contact.

Star Contactor (K2)

Held by same seal-in if required.

Timer (T)

Starts on K1/K2 energizing.

On timeout, opens K2 and closes contact for K3.

Delta Contactor (K3)

Energizes after T times out.

🏷 Typical Control Connections
Control Device Connect
STOP In series with control supply
START To K1 coil
K1 Aux NO After START → holds K1
Timer T coil Parallel K2
Timer T NO Feeds K3 after delay
Interlocks K2 NC in line with K3, and K3 NC in line with K2
⚠️ Important Safety & Checks

✔ Always isolate mains before wiring.
✔ Correct sizing of contactors & overload relay based on motor full load current (FLC).
✔ Mechanical/Electrical interlock required between K2 and K3 so both can’t be ON together.
✔ Timer settings typically 1–3 seconds (depends on motor).
✔ Use proper fuses/MCB protection.

🧠 Explanation in Simple Terms

Star mode → reduced voltage → gentle start.

Delta mode → full energy → full speed.

Timer → controls the switch from Star to Delta.

Safety devices (OL, interlocks) protect your motor and control.

Видео Compressor Auto Star Delta Wiring канала GK electrical Trading Co.