FCC18-03
Over & Under Current Protection Relay — Manual Reset
Dual Over & Under Current Protection in One 18mm Relay
The FCC18-03 is a precision current monitoring relay combining both over-current protection and under-current protection in a single ultra-compact 18mm DIN rail module. Unlike automatic reset models, the FCC18-03 requires manual intervention to restore operation after a fault — making it ideal for applications where a confirmed reset is required before restarting equipment.
Designed for industrial control panels and equipment protection, the FCC18-03 delivers ±1% measurement accuracy with adjustable trip thresholds and configurable time delays via front-panel buttons — no programming or software required.
Quick Specifications
Why Choose the FCC18-03?
Engineered for industrial reliability and precise current monitoring.
Dual Protection
Over-current and under-current monitoring in a single device. Protects against both excessive and insufficient current conditions.
±1% Measurement Accuracy
Electronic current sensing circuit ensures stable, repeatable protection with minimal drift across temperature and load variations.
16A SPDT Output Relay
High-capacity SPDT output handles direct motor and contactor switching. Mechanical life 10 million cycles, electrical life 100,000 cycles.
Button Configuration
Front-panel buttons allow fast, screwdriver-free setup. Configure all parameters without programming or software tools.
Manual Reset Safety
Requires intentional power cycle to reset after fault. Prevents automatic restart, ensuring operator inspection before equipment resumes operation.
How It Works
Understanding the FCC18-03 operating sequence and protection logic.
The FCC18-03 continuously monitors the current flowing through the monitored circuit. When the measured current falls outside the safe operating range (either below the under-current threshold or above the over-current threshold), the relay trips and opens the output contact.
The manual reset function ensures that after a fault condition clears, the relay cannot automatically resume operation. The operator must physically power cycle the relay (disconnect and reconnect power) to restore normal operation. This is essential for safety-critical applications where unexpected restarts could cause injury or damage.
Operating Sequence:
1. Power-On: After powering on, the relay waits for the start delay period (Tr: 0.5-10s adjustable).
2. Monitoring: Once Tr elapses, the relay begins monitoring. If current is within the safe zone (between I< and I>), the NO contact remains closed.
3. Fault Detection: If current exceeds I> or drops below I< and persists for Tt (0.1-20s), the relay trips and opens the NO contact.
4. Manual Reset: After a trip, the relay requires power cycle to reset — even if current returns to normal.
Technical Specifications
Full electrical and mechanical specifications for the FCC18-03 series.
| Parameter | Specification |
|---|---|
| Product Model | FCC18-03 (Over + Under Current, Manual Reset) |
| Input Terminals | A1-A2 (Current sensing via external CT if needed) |
| Supply Voltage - A Code | AC 230V |
| Supply Voltage - D Code | DC 24V |
| Supply Voltage - W Code | AC/DC 12-240V (Wide voltage) |
| Power Consumption | AC: 3.5VA / DC: 2.0W |
| Voltage Tolerance | -15% to +10% |
| AC Current Ranges | A0.5 (0.05-0.5A), A1 (0.1-1A), A2 (0.2-2A), A5 (0.5-5A), A8 (0.8-8A), A16 (1.6-16A) |
| DC Current Ranges | D0.5 (0.05-0.5A), D1 (0.1-1A), D2 (0.2-2A), D5 (0.5-5A), D8 (0.8-8A), D16 (1.6-16A) |
| Start Delay (Tr) | 0.5s ~ 10s (adjustable via buttons) |
| Time Delay (Tt) | 0.1s ~ 20s (adjustable via buttons) |
| Measurement Accuracy | ΔA < ±1% |
| Setting Deviation | 0.1% |
| Temperature Coefficient | 0.05%/°C (at 20°C) |
| Output Contact | 1 × SPDT (NO+NC) |
| Rated Current | 16A / 250V AC |
| Mechanical Life | 1 × 10⁷ operations |
| Electrical Life | 1 × 10⁵ operations |
| Ambient Temperature | -20°C to +60°C |
| Mounting | DIN Rail EN/IEC 60715 (35mm) |
| Dimensions (H × W × D) | 90 × 18 × 64 mm |
| Weight | 75g |
| IP Rating | IP20 |
| Standards | GB/T 14048.5, IEC60947-5-1, EN61812-1 |
Current range is determined by the specific model suffix (A0.5, A1, A2, A5, A8, A16 for AC; D0.5, D1, D2, D5, D8, D16 for DC).
Terminal Connections
SPDT relay output with screw-clamp terminals for fast, reliable wiring.
FCC18-03
Over & Under Current Protection RelayTerminal Connections
- Always de-energize the panel before wiring
- Verify supply voltage matches the module rating (A=AC230V, D=DC24V, W=AC/DC 12-240V)
- Connect load in series with S1-S2 terminals for current monitoring
- 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 / AWG13-20)
- Tighten terminal screws to 0.4 N·m torque specification
- Stripping length: 7mm (0.28in)
Front Panel & Settings
Configure the FCC18-03 using front-panel buttons — no software or programming tools required.
| Parameter | Description | Setting Range |
|---|---|---|
I<
| Under-current Trip Threshold — current below this value triggers a fault | Adjustable within selected current range |
I>
| Over-current Trip Threshold — current above this value triggers a fault | Adjustable within selected current range |
Tt
| Trip Time Delay — delay before confirming a fault after threshold exceeded | 0.1s ~ 20s |
Tr
| Start Delay — delay after power-on before monitoring begins | 0.5s ~ 10s |
LED Indicator Panel
Un — Green LED
Lit = relay is powered on and monitoring the system
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 parameters: Set
I<,I>,Tt, andTrto your desired values using the buttons. - Confirm: Press and hold the button until the LED stops flashing to save your settings.
Note: All settings are made via front-panel buttons. No dial or screwdriver adjustment is required. Refer to the product manual for detailed button operation procedures.
Models & Ordering
Choose the current range and supply voltage that matches your application.
| Model Code | Current Range | Type | Manual |
|---|---|---|---|
| FCC18-03-A0.5 | AC 0.05A - 0.5A | Alternating Current | PDF ↓ |
| FCC18-03-A1 | AC 0.1A - 1A | Alternating Current | PDF ↓ |
| FCC18-03-A2 | AC 0.2A - 2A | Alternating Current | PDF ↓ |
| FCC18-03-A5 | AC 0.5A - 5A | Alternating Current | PDF ↓ |
| FCC18-03-A8 | AC 0.8A - 8A | Alternating Current | PDF ↓ |
| FCC18-03-A16 | AC 1.6A - 16A | Alternating Current | PDF ↓ |
| FCC18-03-D0.5 | DC 0.05A - 0.5A | Direct Current | PDF ↓ |
| FCC18-03-D1 | DC 0.1A - 1A | Direct Current | PDF ↓ |
| FCC18-03-D2 | DC 0.2A - 2A | Direct Current | PDF ↓ |
| FCC18-03-D5 | DC 0.5A - 5A | Direct Current | PDF ↓ |
| FCC18-03-D8 | DC 0.8A - 8A | Direct Current | PDF ↓ |
| FCC18-03-D16 | DC 1.6A - 16A | Direct Current | PDF ↓ |
FCC18 Family — Model Comparison
Compare all four FCC18 series models to find the right protection configuration for your application.
FCC18-01
Over-Current ProtectionFCC18-02
Under-Current ProtectionFCC18-03
Over & Under Current ProtectionFCC18-04
Over & Under Current ProtectionConfiguration Examples
Real-world setting examples for common current monitoring applications.
Example 1 — Motor Protection
| Model | FCC18-03-A5 |
| I> (Over) | 6A (120% of normal) |
| I< (Under) | 3A (60% of normal) |
| Tr (Start) | 3s |
| Tt (Trip) | 1s |
Example 2 — Conveyor Belt
| Model | FCC18-03-A2 |
| I> (Over) | 2.5A (125% of normal) |
| I< (Under) | 1.5A (75% of normal) |
| Tr (Start) | 5s |
| Tt (Trip) | 2s |
Example 3 — Pump Protection
| Model | FCC18-03-A1 |
| I> (Over) | 1.3A (130% of normal) |
| I< (Under) | 0.7A (70% of normal) |
| Tr (Start) | 2s |
| Tt (Trip) | 0.5s |
Example 4 — DC Circuit Monitor
See It In Action
Watch the FCC18 series product overview and demonstration.
Typical Applications
The FCC18-03 protects equipment across a wide range of industrial sectors.
Motor Protection
Protect motors from overload and stall conditions with manual reset for safety.
Conveyor Systems
Detect belt breakage, jams, or motor failures with automatic fault indication.
Pump Monitoring
Protect pumps from dry running, blockage, and electrical faults.
Power Supplies
Monitor DC power supplies and detect over-current or under-current conditions.
Industrial Presses
Safety-critical equipment requiring manual reset after fault conditions.
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 FCC18-03 over and under current protection relay
Manual reset (FCC18-03) requires the operator to physically power down and then power up the relay to restore operation after a fault. Automatic reset (FCC18-04) automatically resumes operation once the fault condition clears. Manual reset is preferred for safety-critical applications where unexpected restarts could cause injury or damage.
The FCC18-03 is available in 12 different current ranges: AC versions (A0.5: 0.05-0.5A, A1: 0.1-1A, A2: 0.2-2A, A5: 0.5-5A, A8: 0.8-8A, A16: 1.6-16A) and DC versions (D0.5: 0.05-0.5A, D1: 0.1-1A, D2: 0.2-2A, D5: 0.5-5A, D8: 0.8-8A, D16: 1.6-16A).
The start delay (Tr) prevents nuisance trips during motor startup or equipment initialization when high inrush currents are normal. When power is applied, the relay waits for the Tr period (0.5s-10s adjustable) before beginning to monitor current. Set Tr long enough to cover the normal startup period of your equipment.
Three supply voltage options are available: A code (AC 230V), D code (DC 24V), and W code (AC/DC 12-240V wide voltage). The W code is recommended for applications where supply voltage may vary or where both AC and DC supplies are needed.
Yes, but you must select the correct model variant. AC current models (suffix A0.5 to A16) are designed for AC current monitoring, while DC current models (suffix D0.5 to D16) are designed for DC current monitoring. Choose the model that matches your application type.
All parameters are configured using the front-panel buttons, not dials or potentiometers. Press and hold the button to enter setting mode, adjust I<, I>, Tt, and Tr values, then press and hold again to save. Refer to the product manual for detailed button operation procedures.
The FCC18-03 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.