FCC18-04
Over & Under Current Protection · Auto-Reset · 18mm DIN Rail
Precision Over & Under Current Protection with Auto‑Reset
The FCC18-04 is a dedicated current monitoring relay that combines over-current and under-current protection in a single 18mm DIN rail module. Designed for automatic operation, it features a fixed 5% hysteresis and fully automatic reset once the current returns to the normal window. No manual intervention is required.
All settings — over-current threshold (I>), under-current threshold (I<), start-up delay (Tr), and trip delay (Tt) — are configured via the front-panel push-buttons. The bright LED display provides clear status of power, relay state, and fault conditions. Ideal for protecting pumps, motors, fans, and heating elements against overload and underload conditions.
Quick Specifications
Why Choose the FCC18-04?
Engineered for reliable current monitoring with true auto-reset functionality.
Over + Under Current
Simultaneously monitors for excessive current (overload) and low current (underload/loss of load) with independent thresholds.
Auto‑Reset with 5% Hysteresis
Relay automatically re-closes when current returns to 95% of over-current setting or 105% of under-current setting. No manual button press needed.
16A SPDT Output
High-capacity relay contact switches up to 16A, suitable for direct control of contactors, solenoids, and small motors.
Push-Button Setting
Four tactile buttons set I>, I<, Tr, and Tt. No screwdriver or dials — clear digital configuration with LED feedback.
Wide Current Range
12 models cover 0.05A to 16A for both AC and DC circuits. Select the suffix (A0.5 … D16) that matches your load.
Protection Logic & Timing
Clear visual diagram of over-current, under-current, and auto-reset behavior.
The FCC18-04 operates with two independent thresholds: I> (over-current) and I< (under-current). After power-up and the Tr (start-up delay), the relay begins monitoring. If the current exceeds I> or falls below I< for longer than Tt (trip delay), the output relay opens.
Thanks to the auto-reset function, the relay automatically re-closes when the current recovers to within 95% of I> (for over-current) or 105% of I< (for under-current). No manual reset is ever required.
Technical Specifications
Electrical and mechanical data for FCC18-04 series.
| Parameter | FCC18-04 (All current ranges) |
|---|---|
| Protection Functions | Over-current (I>) + Under-current (I<) |
| Reset Mode | Automatic (fixed 5% hysteresis) |
| Current Ranges (AC/DC) | 0.05-0.5A, 0.1-1A, 0.2-2A, 0.5-5A, 0.8-8A, 1.6-16A (see model table) |
| Setting Method | Front push-buttons (I>, I<, Tr, Tt) |
| Start-up Delay (Tr) | 0.1s – 2 adjustable |
| Trip Delay (Tt) | 0.1s – 20s adjustable |
| Measurement Accuracy | ΔI ≤ ±1% (of full scale) |
| Temperature Coefficient | 0.05%/°C at 20°C |
| Hysteresis | 5% fixed (95% for over-current, 105% for under-current) |
| Supply Voltage (depends on model) | 24V DC, 230V AC, or 12-240V AC/DC (universal) |
| Power Consumption | AC 3.5VA / DC 2.0W |
| Output Contact | 1 × SPDT (NO+NC) |
| Rated Current / Voltage | 16A / 250V AC (resistive) |
| Mechanical Life | 10⁷ operations |
| Electrical Life | 10⁵ operations (at rated load) |
| Ambient Temperature | -20°C to +60°C (operating) |
| Mounting | 35mm DIN Rail (EN/IEC 60715) |
| Dimensions (H×W×D) | 90 × 18 × 64 mm |
| Weight | ~75g |
| IP Rating | IP20 |
| Standards | GB/T 14048.5, IEC60947-5-1, EN61812-1 |
* Specific current range is determined by the model suffix (e.g., FCC18-04-A5 = 0.5-5A AC). Supply voltage must be specified at order.
Terminal Connections
SPDT relay output with screw-clamp terminals for fast, reliable wiring.
FCC18-04 – Single‑Phase AC/DC Current Monitoring
- De-energize panel before wiring.
- Use appropriate wire gauge for 16A load (min 1.5mm² / AWG16).
- For current input, connect in series with the load (or use external CT for high currents).
- Terminal torque: 0.4 N·m. Stripping length: 7mm.
- Ensure supply voltage matches relay rating.
Front Panel & Button Settings
All parameters are set via the four push-buttons — no dials, no tools.
| Parameter | Description | Setting Range / Notes |
|---|---|---|
I>
| Over-current trip threshold | Adjustable within the model's range (e.g., 0.5-5A for A5). Press button to increase. |
I<
| Under-current trip threshold | Must be set lower than I>. Adjustable within range. |
Tr
| Start-up delay (inhibit time) | 0.1s – 30s, step adjustable via button. |
Tt
| Trip delay (debounce time) | 0.1s – 30s, independent for over/under trips. |
LED Indicator Panel
PWR — Green LED
ON = supply present. Flashing during Tr start-up delay.
FLT — Red LED
ON = fault condition (over/under current trip). OFF = normal.
⚙ How to Set Parameters (Button Operation)
- Press and hold the desired parameter button (I>, I<, Tr, Tt) for 3 seconds. The corresponding LED flashes.
- Use short presses to increment the value. Hold to scroll faster.
- Release the button; after 5 seconds the value is saved and the LED stops flashing.
- Repeat for other parameters. No password or menu — direct setting.
Note: I< cannot be set higher than I>. If attempted, the relay will ignore the setting and keep the previous valid value.
Models & Ordering Information
Select the current range and supply voltage that matches your application.
| Model Code | Current Type | Measurement Range | Manual (PDF) |
|---|---|---|---|
| FCC18-04-A0.5 | AC | 0.05 – 0.5 A | PDF ↓ |
| FCC18-04-A1 | AC | 0.1 – 1 A | PDF ↓ |
| FCC18-04-A2 | AC | 0.2 – 2 A | PDF ↓ |
| FCC18-04-A5 | AC | 0.5 – 5 A | PDF ↓ |
| FCC18-04-A8 | AC | 0.8 – 8 A | PDF ↓ |
| FCC18-04-A16 | AC | 1.6 – 16 A | PDF ↓ |
| FCC18-04-D0.5 | DC | 0.05 – 0.5 A | PDF ↓ |
| FCC18-04-D1 | DC | 0.1 – 1 A | PDF ↓ |
| FCC18-04-D2 | DC | 0.2 – 2 A | PDF ↓ |
| FCC18-04-D5 | DC | 0.5 – 5 A | PDF ↓ |
| FCC18-04-D8 | DC | 0.8 – 8 A | PDF ↓ |
| FCC18-04-D16 | DC | 1.6 – 16 A | PDF ↓ |
FCC18 Family — Model Comparison
Compare all four FCC18 current monitoring relays to find the right protection.
| Model | Over-Current | Under-Current | Reset Mode | Voltage Type | Ideal For |
|---|---|---|---|---|---|
| FCC18-01 | Adjustable | — | Manual / Auto | AC / DC | Over-current protection with selectable reset mode for flexible applications |
| FCC18-02 | — | Adjustable | Manual / Auto | AC / DC | Under-current protection (e.g., no-load detection) with selectable reset mode |
| FCC18-03 | Adjustable | Adjustable | Manual Only | AC / DC | Over and under-current protection, manual reset ensures operator acknowledgment |
| FCC18-04 | Adjustable | Adjustable | Auto Only | AC / DC | Over and under-current protection, automatic restart when conditions normalize |
Setting Examples
Typical configuration scenarios for the FCC18-04.
Pump Dry-Run Protection
| I> (Over) | 4.5 A |
| I< (Under) | 1.2 A |
| Tr (Start delay) | 5 s |
| Tt (Trip delay) | 3 s |
| Action | Trips if current < 1.2A (dry run) or >4.5A (clogged). Auto-resets. |
Fan Belt Breakage
| I> | 1.8 A |
| I< | 0.6 A |
| Tr | 10 s |
| Tt | 2 s |
| Action | Trips if belt slips (low current) or motor overloads. |
Heater Element Monitor
DC Motor Stall
| I> | 4.0 A |
| I< | 0.8 A |
| Tr | 3 s |
| Tt | 0.5 s |
| Action | Over-current indicates stall; under-current indicates no load. |
See It In Action
Watch the FCC18-04 product overview and configuration demo.
Typical Applications
The FCC18-04 protects critical loads in industrial and commercial environments.
Pump Protection
Detect dry-running (under-current) and clogged impeller (over-current). Auto-resets after fault clears.
HVAC & Fans
Monitor fan motor current; trip on belt breakage (low current) or bearing failure (high current).
Conveyor Systems
Detect jam (over-current) or broken chain (under-current). Fully automatic restart.
Heating Elements
Monitor resistive loads for open circuit (under-current) or partial short (over-current).
Machine Tools
Protect spindle and coolant pump motors against overload and underload conditions.
Ready to Order the FCC18-04?
Contact us for a quotation, request samples, or discuss OEM customizations.
Frequently Asked Questions
Common questions about the FCC18-04 current protection relay
Auto-reset means the relay automatically re-energizes (closes the output contact) as soon as the current returns to the normal range, without any manual intervention. For over-current, reset occurs when current falls below 95% of the I> setting. For under-current, reset occurs when current rises above 105% of the I< setting.
Choose the model whose range fully covers your load's normal operating current. For best accuracy, select a range where the normal current is between 20% and 80% of the full scale. For example, if your motor draws 2.5A, the FCC18-04-A5 (0.5-5A) is ideal.
Yes, but you must order the correct suffix: models with "A" (e.g., FCC18-04-A5) are for AC current. Models with "D" are for DC current. The internal circuitry differs. Ensure you match the current type.
Tr masks the high inrush current that occurs when motors or transformers start. During Tr, the relay ignores the measured current. This prevents false over-current trips. Set Tr slightly longer than the typical inrush duration.
No. The FCC18-04 is designed exclusively for automatic reset. If you need a manual reset option for over+under current, consider the FCC18-03 model.
Press and hold the corresponding button (I>, I<, Tr, Tt) for 3 seconds. The LED flashes. Short press to increment the value. After 5 seconds of inactivity, the value is saved. The display is not numeric; setting is based on counting steps within the range. Refer to the manual for exact step values.
Yes, we offer OEM branding (custom logo, model number, color) and custom current ranges for volume orders. Contact info@fiicco.com with your requirements.