Phase Control Relay
Phase Loss, Sequence, Voltage & Asymmetry
Comprehensive three-phase monitoring with fixed 8% asymmetry detection, adjustable over/under voltage (2%–20%), configurable time delay (0.1–30s), and full LED diagnostics — engineered for uncompromising protection of motors and sensitive loads.
📋 Models & Ordering
| Model | System Type | Supply Voltage | Terminals | Protection Functions | Datasheet |
|---|---|---|---|---|---|
| FCP18-03A | 3-phase 3-wire (L-L) | 173–275V AC | L1 – L2 – L3 | Phase Loss + Seq. + OV/UV + Asym. (8%) | 📄 Download PDF |
| FCP18-03B | 3-phase 4-wire (L-N) | 100–160V AC | L1 – L2 – L3 – N | Phase Loss + Seq. + OV/UV + Asym. (8%) | 📄 Download PDF |
| FCP18-03C | 3-phase 3-wire (L-L) | 310–480V AC | L1 – L2 – L3 | Phase Loss + Seq. + OV/UV + Asym. (8%) | 📄 Download PDF |
| FCP18-03D | 3-phase 4-wire (L-N) | 180–278V AC | L1 – L2 – L3 – N | Phase Loss + Seq. + OV/UV + Asym. (8%) | 📄 Download PDF |
💡 Model selection guide: Choose A/C for 3-phase 3-wire (L-L) systems, or B/D for 3-phase 4-wire (L-N) systems. A/B covers lower voltage ranges; C/D covers higher voltage ranges. All models provide Phase Loss, Phase Sequence, adjustable Over/Under Voltage, and a fixed 8% Asymmetry threshold with 0.1–30s time delay.
⚙️ Technical Specifications
🔌 Input — Measuring (All Models)
| Supply Terminal (A/C) | L1 – L2 – L3 |
| Supply Terminal (B/D) | L1 – L2 – L3 – N |
| Monitoring Terminal | Same as supply terminal |
| Supply Voltage (A) | 173–275V AC L-L |
| Supply Voltage (B) | 100–160V AC L-N |
| Supply Voltage (C) | 310–480V AC L-L |
| Supply Voltage (D) | 180–278V AC L-N |
| Supply Frequency | 45–60Hz |
🛡️ Monitoring Function
| Phase Failure | ✔ (Response < 200ms) |
| Phase Sequence | ✔ (Response < 500ms) |
| Overvoltage | 2%–20% adjustable |
| Undervoltage | -20%–-2% adjustable |
| Asymmetry | 8% fixed |
| Time Delay | 0.1–30s |
🔌 Output
| Contact | 1 × 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 | SPDT: 11(COM)-12(NC)-14(NO) |
| Pollution Degree | 2 |
| Max. Cable Size | AWG 13–20 / 0.4 N·m |
| Setting Deviation | 0% – Digital Setting |
💡 Panel LED Indicators
| LED | Color | Status | Meaning |
|---|---|---|---|
| Un | Green | OFF | Supply voltage not applied |
| Un | Green | ON | Supply voltage applied |
| P | Red | ON | Phase normal (correct sequence, all phases present) |
| P | Red | Flashing | Phase sequence error |
| P | Red | OFF | Phase loss detected |
| R | Red | OFF | NC (11-12) contact closed |
| R | Red | ON | NO (11-14) contact closed |
📈 Function Diagram – Phase Loss & Sequence Protection
• The relay continuously monitors the three-phase supply connected to L1-L2-L3 (and N for 4-wire models).
• When all three phases are present and in correct sequence, the output relay R closes (NO contact 11-14 makes, NC 11-12 breaks) after the set time delay. The P LED stays ON.
• If a phase loss is detected, the output relay R opens immediately (within 200ms). The P LED turns OFF.
• If a phase sequence error is detected, the output relay R opens immediately. The P LED flashes.
• When the fault clears, the relay automatically re-closes after the set time delay.
📈 Function Diagram – Overvoltage & Undervoltage Protection
• The relay continuously monitors the voltage level against the set overvoltage threshold (adjustable 2%–20% above nominal) and undervoltage threshold (adjustable -20%–-2% below nominal).
• If voltage goes above the overvoltage threshold, the output relay R opens after the set time delay T (configurable 0.1–30s). When the voltage drops back below the overvoltage threshold, R automatically re-closes (no delay).
• If voltage drops below the undervoltage threshold, the output relay R opens after the set time delay T. When the voltage rises back above the undervoltage threshold, R automatically re-closes.
• The configurable time delay helps prevent nuisance tripping caused by momentary voltage transients.
📈 Function Diagram – Asymmetry (Phase Imbalance) Protection
• The relay measures the voltage difference between the three phases and calculates the asymmetry (imbalance) percentage.
• When the asymmetry exceeds the fixed 8% threshold, the output relay R opens after the set time delay T (0.1–30s).
• If the asymmetry drops back below 8%, the output relay R automatically re-closes.
• This protection prevents motors from running with unbalanced supply voltages, which causes overheating and premature failure.
🎬 See it in Action
🔧 Wiring & Terminal Layout
Terminal Identification
3-phase 3-wire models (A/C): Connect L1, L2, L3 directly. No neutral connection required.
3-phase 4-wire models (B/D): Connect L1, L2, L3, and N. The wiring diagram shown is for 4-wire models. For 3-wire models, simply omit the N terminal.
Shown: 4-wire (L-N) wiring for B/D models. For A/C models, omit the N terminal.
🛠️ 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.
- Set Rated Voltage (Un): Use the button to set the correct input voltage for your three-phase system. Refer to the setting details table for available options.
-
Set Overvoltage (U>) & Undervoltage (U<) Rate: Configure the overvoltage threshold (2%–20%) and undervoltage threshold (-20%–-2%).
💡 Note: When setting over & under voltage range, if the green LED is ON, add +1% to the scale reading for accurate threshold setting.
- Set Time Delay (Tt): Choose the desired time delay from 0.1 to 30 seconds. This delay applies to initial start-up, and to the delayed opening of the output relay when an overvoltage, undervoltage, or asymmetry fault is detected.
- Confirm and Store: After all parameters are adjusted, press and hold the button until the LED stops flashing. The settings are stored and take effect immediately.
🏭 Typical Applications
Prevents overheating from phase imbalance in critical three-phase motors
Protects scroll and screw compressors from voltage asymmetry and sequence faults
Safeguards deep-well pumps from unbalanced supply and phase loss
Ensures correct rotation and stable voltage for material handling drives
Maintains power quality for sensitive servo drives and spindle motors
Protects CRAC units and fan walls from phase anomalies
🔗 Related Products
Explore other phase relays in the FCP18 series, or time relays in the FCT18 series:
❓ Frequently Asked Questions
📞 Need a Quote or Technical Support?
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