FCT18-ST Series
Star-Delta Time Relay
Star-Delta Time Relay
for Motor Starting
Industrial-grade star-delta timer with digital setting, ultra-wide voltage range, and smooth transition for reduced inrush current in motor starting applications.
Wide-voltage 12–240V AC/DC
0.1s–40min time range
0% setting deviation
0.2% repeat accuracy
DIN rail mount
18mm slim design
2×SPDT
16A @ 250V AC
Star-Delta Function
IP40 Front
0%
Setting Deviation
Digital button configuration eliminates the 5–10% deviation typical of potentiometer-based timers.
0.2%
Repeat Accuracy
Matches top international brands for consistent, reliable timing cycle after cycle.
Anti-Misoperation Lock
Long-press required for reconfiguration — prevents accidental parameter changes in the field.
Enhanced Anti-EMI Design
Reinforced circuit ensures stable operation even in complex electromagnetic environments.
12–240V
Wide Supply Voltage
AC/DC universal — one relay covers virtually all common control voltages worldwide.
0.1s–40m
Star Time Range
Fine-adjustable star connection time from 0.1 seconds up to 40 minutes.
📋 Model & Ordering
| Model | Supply Voltage | Output Contact | Function | Time Range | Datasheet |
|---|---|---|---|---|---|
| FCT18-ST | 12–240V AC/DC | 2 × SPDT | Star-Delta | 0.1s – 40min | 📄 Download PDF |
💡 This is a dedicated Star-Delta timer with 2 SPDT outputs for star and delta contactor control. No external control signal (S) is required.
⚙️ Technical Specifications
🔌 Input
| Input Terminal | A1 – A2 |
| Supply Voltage | 12–240V AC/DC |
| Power Consumption | AC 3.5VA / DC 2.0W |
| Voltage Tolerance | -15% ~ +10% |
⏱️ Time Circuit
| Function | Star-Delta |
| Time Range (Star) | 0.1s – 40min |
| Time Setting | Button (digital) |
| Time Deviation | 0% – Digital Setting |
| Repeat Accuracy | 0.2% |
| Temperature Coefficient | 0.01%/°C (at 20°C) |
🔌 Output
| Contact | 2 × SPDT |
| Rated Current | 16A @ 250V AC |
| Mechanical Life | 1×10⁷ operations |
| Electrical Life | 1×10⁵ operations |
📐 Physical & Environmental
| Dimensions | 18 × 90 × 64 mm |
| Mounting | DIN rail EN 60715 |
| Protection Degree | IP40 (front) / IP10 (terminals) |
| Operating Temp. | -20°C ~ +55°C |
| Storage Temp. | -30°C ~ +70°C |
📜 Standards & Certifications
| Compliance | GB/T 14048.5, IEC 60947-5-1, EN 6812-1 |
| Contact Configuration | 11(COM)-12(NC)-14(NO) / 21(COM)-22(NC)-24(NO) |
| Pollution Degree | 2 |
| Max. Cable Size | AWG 13–20 / 0.4 N·m |
📈 Function Diagram – Star-Delta Operation
• After power-on, output R1 closes the star contactor and the main contactor, and timing T1 starts (star connection time period).
• At the end of T1, output R1 reverts to its initial state, opening the star contactor and starting the transition time T2.
• At the end of T2, output R2 closes, engaging the delta contactor for full-load run.
• This sequence ensures a smooth, controlled transition from star to delta, reducing mechanical and electrical stress.
🎬 See it in Action
🔧 Wiring & Terminal Layout
Terminal Identification
A1 — L / + (Supply)
A2 — N / - (Supply)
11 — COM (R1)
12 — NC (R1)
14 — NO (R1)
21 — COM (R2)
22 — NC (R2)
24 — NO (R2)
⚠️ Safety Note: Keep the power supply disconnected during the entire installation process. Carefully check the wiring diagram and follow it correctly. Adhere to the specified voltage and current limits for each connection terminal.
R1 controls the star contactor, R2 controls the delta contactor. The main contactor is typically wired in parallel with the supply.
🛠️ Parameter Setting Guide
- Enter Parameter Setting Mode: Press and hold the button until the LED starts flashing. This indicates you have entered the configuration mode.
-
Adjust Star Time (T1) & Fine Time: Use the button to set the desired star time (coarse) and fine time adjustment. The scale markings on the front panel guide your setting.
💡 Note: When the green LED is ON during time range setting, add +5% to the value indicated on the scale for accurate timing.
- Confirm New Parameters: After adjusting to your desired values, press and hold the button until the LED stops flashing. The new parameters are now stored.
- Make Parameters Effective: After confirming parameters, you must power off and restart the device to activate the new settings.
🏭 Typical Applications
Motor Start Control
Smooth star-delta transition to reduce inrush current and voltage dips
Smooth star-delta transition to reduce inrush current and voltage dips
Pump Systems
Soft start for water pumps to prevent water hammer and pipe stress
Soft start for water pumps to prevent water hammer and pipe stress
Compressor Control
Reduce mechanical stress during compressor startup
Reduce mechanical stress during compressor startup
Industrial Fans
Minimize voltage drops on fan startup in ventilation systems
Minimize voltage drops on fan startup in ventilation systems
Conveyor Belts
Gradual acceleration to avoid belt slippage and mechanical shock
Gradual acceleration to avoid belt slippage and mechanical shock
HVAC Systems
Reliable starting for large air handling units and chillers
Reliable starting for large air handling units and chillers
🔗 Related Products
Explore other time relays in the FCT18 series:
❓ Frequently Asked Questions
🔹 What is a Star-Delta relay used for?
The FCT18-ST relay is designed to start three-phase induction motors in star connection to reduce starting current, then automatically switch to delta connection for full-speed operation. This significantly reduces mechanical stress and voltage dips on the supply line.
🔹 How do I set the star time (T1)?
Enter parameter setting mode by long-pressing the button until the LED flashes. Adjust the time range and fine time using the button. When the green LED is on during range setting, add 5% to the scale reading for precise timing. Confirm by long-pressing until the LED stops flashing, then power-cycle the device to activate the new setting.
🔹 What is the transition time (T2) and can it be adjusted?
T2 is a fixed internal transition time (approximately 50ms) that ensures a safe break-before-make interval between star and delta contactors. It is not user-adjustable and is optimized to prevent short circuits during switching.
🔹 Can I use this relay on both AC and DC supply?
Yes. The FCT18-ST accepts 12–240V AC or DC on terminals A1–A2, making it suitable for virtually any control panel worldwide.
🔹 What is the mechanical life of the output contacts?
The relay has a mechanical life of 1×10⁷ operations, ensuring long-term reliability even in demanding industrial environments. The electrical life is 1×10⁵ operations at rated load.
🔹 Does this relay require an external control signal?
No. The FCT18-ST operates automatically once supply voltage is applied. It does not have an S terminal and does not require any external trigger — the timing sequence starts immediately upon power-up.
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