FCP18-06
Fixed Asymmetry & Phase Sequence Protection Relay
Fixed Thresholds — OV/UV ±15%, Asymmetry 8%, Phase Loss All in One
The FCP18-06 is a four-in-one three-phase monitoring relay combining over-voltage, under-voltage, fixed 8% voltage asymmetry (unbalance), and phase sequence/loss detection — all with factory-fixed thresholds — in a single ultra-compact 18mm DIN rail module.
Compared with the FCP18-03 and FCP18-04 (which offer adjustable OV/UV thresholds), the FCP18-06 uses factory-fixed thresholds for all parameters — ±15% for both over-voltage and under-voltage, 8% for asymmetry, and a fixed 5-second delay. This makes it the most cost-effective four-function relay in the FCP18 family, ideal when standard fixed thresholds match your protection profile.
Quick Specifications
Why Choose the FCP18-06?
Four fixed-threshold protections in one compact module — the most cost-effective all-in-one three-phase relay.
4-in-1 Fixed Protection
Over-voltage, under-voltage, 8% asymmetry, and phase sequence/loss — all four with factory-fixed thresholds at the lowest cost in the FCP18 family.
Fixed Thresholds OV/UV ±15%
Both over-voltage and under-voltage are factory-fixed at ±15% — the most common fixed threshold for general industrial protection.
8% Fixed Asymmetry
Industry-standard fixed 8% voltage unbalance threshold — NEMA and IEC recommended protection level for general-purpose three-phase motors.
16A SPDT Output Relay
High-capacity SPDT output handles direct motor and contactor switching. Mechanical life 10 million cycles, electrical life 100,000 cycles.
Fixed 5s Time Delay
Factory-fixed 5-second trip delay prevents nuisance tripping during motor startup transients. No adjustment needed — always-on reliability.
Four Protection Functions
Four factory-fixed threshold protections — over-voltage, under-voltage, fixed 8% asymmetry, and phase sequence/loss.
The FCP18-06 monitors four fault conditions simultaneously. Over-voltage and under-voltage functions trip when voltage exceeds ±15% of rated value for the fixed 5-second delay. The asymmetry function continuously calculates the unbalance ratio: Asy = (Umax − Umin) / Uavg × 100%. When this exceeds the fixed 8% threshold, the relay trips after 5 seconds. The phase sequence function monitors L1, L2, L3 order and immediately detects phase loss or reversal.
All four thresholds are factory-fixed — no field adjustment needed. This makes the FCP18-06 the most cost-effective four-function relay in the FCP18 family, ideal when standard fixed thresholds match your protection requirements.
1. Over-voltage Protection (U> — +15% Fixed)
When the measured line voltage rises above the +15% fixed over-voltage threshold above the rated voltage (Un) and remains high for the fixed 5-second delay, the relay trips and opens the output contact.
- Trip threshold: Un + 15% (fixed, factory-calibrated)
- Time delay: Fixed at 5 seconds
- Reset: Automatic reset once voltage returns to normal
2. Under-voltage Protection (U< — −15% Fixed)
When the measured line voltage falls below the −15% fixed under-voltage threshold below the rated voltage (Un) and remains low for the fixed 5-second delay, the relay trips.
- Trip threshold: Un − 15% (fixed, factory-calibrated)
- Time delay: Fixed at 5 seconds
- Application: Essential for motor protection and compressor control systems
3. Voltage Asymmetry / Unbalance Detection (8% Fixed)
Voltage asymmetry occurs when the three phase voltages are not equal in magnitude. The FCP18-06 calculates: Asy = (Umax − Umin) / Uavg × 100%. When this exceeds the fixed 8% threshold, the relay trips after 5 seconds.
- Trip threshold: Fixed at 8% — no adjustment needed
- Formula: Asy = (Umax − Umin) / Uavg × 100%
- Trip time: After 5s fixed Tt delay
4. Phase Sequence & Phase Loss Protection
The FCP18-06 monitors the rotational sequence of the three-phase supply (L1 → L2 → L3). If the phase sequence is reversed or any phase is interrupted, the relay immediately trips. The red P LED shows status: lit = correct sequence, flashing = fault.
- P LED lit: All three phases present and in correct sequence
- P LED flashing: Phase loss or sequence reversed
- Trip behavior: Immediate — no additional time delay
Technical Specifications
Full electrical and mechanical specifications for the FCP18-06 series.
| Parameter | FCP18-06A / 06C | FCP18-06B / 06D |
|---|---|---|
| System Type | 3-Phase 3-Wire (L1-L2-L3) | 3-Phase 4-Wire (L1-L2-L3-N) |
| Voltage Range (L-L) | 173-275V AC (A) / 310-480V AC (C) | N/A for 4-wire models |
| Voltage Range (L-N) | N/A for 3-wire models | 100-160V AC (B) / 180-278V AC (D) |
| Rated Frequency | 45Hz - 65Hz | 45Hz - 65Hz |
| Voltage Tolerance | −15% to +10% | −15% to +10% |
| Over/Under Voltage | ±15% Fixed (factory-set) | ±15% Fixed (factory-set) |
| Asymmetry Setting | 8% Fixed (factory-set) | 8% Fixed (factory-set) |
| Time Delay (Tt) | 5s Fixed | 5s Fixed |
| Measurement Accuracy | ΔV less than ±1% | ΔV less than ±1% |
| Temperature Coefficient | 0.05%/°C at 20°C | 0.05%/°C at 20°C |
| Output Contact | 1 × SPDT (NO+NC) | 1 × SPDT (NO+NC) |
| Rated Current | 16A / 250V AC | 16A / 250V AC |
| Mechanical Life | 1 × 107 operations | 1 × 107 operations |
| Electrical Life | 1 × 105 operations | 1 × 105 operations |
| Ambient Temperature | −20°C to +60°C | −20°C to +60°C |
| Mounting | DIN Rail EN/IEC 60715 (35mm) | DIN Rail EN/IEC 60715 (35mm) |
| Dimensions (H × W × D) | 90 × 18 × 64 mm | 90 × 18 × 64 mm |
| Weight | 68g | 68g |
| IP Rating | IP20 | IP20 |
| Standards | GB/T 14048.5, IEC60947-5-1, EN61812-1 | GB/T 14048.5, IEC60947-5-1, EN61812-1 |
Voltage codes: A = 173-275V L-L (3-wire) | B = 100-160V L-N (4-wire) | C = 310-480V L-L (3-wire) | D = 180-278V L-N (4-wire). Other voltages available on request.
Terminal Connections
SPDT relay output with screw-clamp terminals for fast, reliable wiring.
FCP18-06A / 06C — 3-Phase 3-Wire (L1-L2-L3)
FCP18-06B / 06D — 3-Phase 4-Wire (L1-L2-L3-N)
- Always de-energize the panel before wiring
- Verify supply voltage matches the module rating before powering on
- Connect L1, L2, L3 (and N for 4-wire models) to the corresponding system phases
- Terminal 11 = Common, 12 = NC, 14 = NO — wire your load to the appropriate contact
- Use correct wire gauge for 16A load current (min. 1.5mm²)
- Tighten terminal screws to 0.4 N·m torque specification
- Stripping length: 7mm (AWG13-20)
Front Panel & Settings
Four fixed factory-calibrated thresholds — no field adjustment needed. Simply set the rated voltage (Un) and the relay is ready.
| Parameter | Description | Setting Range |
|---|---|---|
Un |
Rated Input Voltage (system voltage) — the nominal voltage of the three-phase installation | See voltage code table in Models section |
Asy |
Voltage Asymmetry (unbalance) — factory-fixed at 8%, no adjustment needed | Fixed at 8% (no adjustment required) |
Tt |
Time Delay before trip — factory-fixed at 5 seconds | 5s fixed (no adjustment required) |
LED Indicator Panel
Un — Green LED
Lit = relay is powered on and monitoring the system
P — Red LED
Lit = correct phase sequence. Flashing = fault detected (phase loss or reversal)
R — Red LED
Lit = NO contact (terminals 11-14) is closed, relay is energized
⚙ How to Set Parameters
- Enter setting mode: Press and hold the button until the LED starts flashing.
- Adjust settings: Set
Unto match your system voltage. All four protection thresholds (OV ±15%, UV −15%, Asy 8%, Tt 5s) are factory-fixed — no further adjustment needed. - Confirm: Press and hold the button until the LED stops flashing to save your settings.
Note: When the green LED is on, add 1% to trip thresholds: over-voltage at Un + 16%, under-voltage at Un − 16%, asymmetry at 9%.
Models & Ordering
Choose the voltage configuration that matches your three-phase system.
| Model Code | System Type | Voltage Range (L-L) | Voltage Range (L-N) | Manual |
|---|---|---|---|---|
| FCP18-06A | 3-Phase 3-Wire | 173, 190, 198, 208, 220, 230, 240, 250, 260, 275 V | N/A | PDF ↓ |
| FCP18-06B | 3-Phase 4-Wire | N/A | 100, 110, 115, 120, 127, 133, 139, 145, 151, 160 V | PDF ↓ |
| FCP18-06C | 3-Phase 3-Wire | 310, 328, 345, 365, 380, 400, 415, 440, 460, 480 V | N/A | PDF ↓ |
| FCP18-06D | 3-Phase 4-Wire | N/A | 180, 190, 200, 210, 220, 232, 240, 255, 266, 278 V | PDF ↓ |
FCP18 Family — Model Comparison
Compare all six FCP18 series — FCP18-06 is the only model with fixed ±15% OV/UV thresholds.
| Model | Over-voltage | Under-voltage | Asymmetry | Time Delay | Phase Seq. | Phase Loss | Ideal For |
|---|---|---|---|---|---|---|---|
| FCP18-01 | — | — | — | 5s fixed | ✓ | ✓ | Phase sequence/loss only, budget applications |
| FCP18-02 | ✓ | ✓ | — | 0.1~30s | ✓ | ✓ | OV/UV + phase protection — cost-effective motor & pump protection |
| FCP18-03 | ✓ | ✓ | 8% fixed | 0.1~30s | ✓ | ✓ | Full protection incl. fixed asymmetry — general motor & compressor |
| FCP18-04 | ✓ | ✓ | 5%~15% adj. | 5s fixed | ✓ | ✓ | Adjustable asymmetry + OV/UV — CNC, medical, precision equipment |
| FCP18-05 | — | — | 5%~15% adj. | 0.1~30s | ✓ | ✓ | Adjustable asymmetry + phase only — dedicated unbalance monitoring |
| FCP18-06 | 15% fixed | 15% fixed | 8% fixed | 5s fixed | ✓ | ✓ | All-fixed 4-in-1: OV/UV ±15%, Asy 8% fixed, phase seq. — lowest cost |
Configuration Examples
Real-world setting examples for common three-phase system voltages.
FCP18-06A — 208V System
| Un (Voltage) | 208V |
| Asy (Fixed) | 8% |
| Tt (Delay) | 5s |
FCP18-06A — 400V System
| Un (Voltage) | 400V |
| Asy (Fixed) | 8% |
| Tt (Delay) | 12s (motor start) |
FCP18-06B — 120V System
| Un (Voltage) | 120V |
| Asy (Fixed) | 8% |
| Tt (Delay) | 3s |
FCP18-06D — 230V System
| Un (Voltage) | 230V |
| Asy (Fixed) | 8% |
| Tt (Delay) | 20s (heavy load) |
See It In Action
Watch the FCP18 series product overview and demonstration.
Typical Applications
The FCP18-06 is purpose-built for fixed 8% asymmetry monitoring across a wide range of industrial sectors.
Motor Protection
General-purpose three-phase motor protection with industry-standard 8% asymmetry threshold.
HVAC & Compressors
Protect compressors and HVAC equipment with the most widely specified asymmetry threshold.
Power Distribution
Panel-level asymmetry monitoring in LV/MV switchgear and distribution boards.
Pump Panels
Cost-effective protection for water pump panels, irrigation systems, and booster stations.
Industrial Automation
General-purpose protection for PLC-controlled systems and automated industrial equipment.
Ready to Order or Need More Details?
Download the full technical manual or contact the FIICCO team for pricing, samples, and OEM options.
Frequently Asked Questions
Common questions about the FCP18-06 fixed asymmetry protection relay
The FCP18-06 does include over-voltage and under-voltage protection — both factory-fixed at ±15% of rated voltage. The FCP18-03 includes adjustable OV/UV protection (±2%~20%) in addition to the fixed 8% asymmetry and phase functions. The FCP18-06 is the right choice when you need the industry-standard 8% asymmetry protection at the lowest cost, at the lowest cost in the FCP18 family.
Both the FCP18-06 and FCP18-05 include fixed asymmetry and phase sequence/loss protection. The FCP18-06 additionally includes over-voltage and under-voltage protection (both ±15% fixed). The key difference is the asymmetry threshold: the FCP18-06 has a fixed 8% threshold (industry standard, no adjustment), while the FCP18-05 has an adjustable threshold (5%~15%) via the front-panel Asy setting. Choose FCP18-06 when you need all four protections at the lowest cost; choose FCP18-05 when you need adjustable asymmetry sensitivity without OV/UV.
The 8% voltage asymmetry threshold is the most widely specified setting in industrial motor protection standards worldwide. NEMA and IEC standards identify 8% unbalance as the typical threshold above which three-phase motors experience significant overheating and reduced lifespan. The FCP18-06 uses this industry-standard setting, making it the most universally applicable asymmetry relay without requiring any setting adjustment.
No. The FCP18-06 is specifically designed for three-phase systems and requires three-phase input (L1, L2, L3) to operate. For single-phase voltage monitoring, consider a single-phase voltage monitoring relay from FIICCO's product range.
The time delay setting depends on your application. For fast-trip protection without motor starting conditions, use a short delay such as 0.1s or 3s. For motor protection where inrush current causes brief voltage dips during startup, use a longer delay (e.g., 12s, 20s, or 30s) to prevent nuisance tripping. The FCP18-06's 0.1~30s adjustable range covers both scenarios.
The FCP18-06 has a single SPDT (single-pole double-throw) relay contact rated 16A/250V AC. Terminal 11 is the common, 12 is normally closed (NC), and 14 is normally open (NO). Wire your load between terminal 11 and terminal 14 for normally open operation — the circuit is energized when the relay trips.
The FCP18-06 is certified to CE, RoHS, and meets the standards of IEC 60947-5-1, GB/T 14048.5, and EN 61812-1. This makes it suitable for industrial automation applications in Europe, Asia, and other global markets.
Yes. FIICCO provides OEM services including custom branding (logo, model number, color), tailored specifications, and custom packaging for orders of 100+ units. Factory-direct pricing ensures competitive costs for OEM customers. Contact us at info@fiicco.com with your requirements and quantity for a tailored quotation.