FCV18-01 Series

Voltage Control Relay
Over & Under Voltage — Manual Reset

Precision single-phase voltage monitoring relay with independent overvoltage and undervoltage thresholds, adjustable time delay, and manual reset function — ideal for protecting sensitive equipment where automatic restart is not desired.

12–240V AC/DC Supply Over/Under Voltage Protection Manual Reset ≤1% / ±1V Accuracy DIN rail mount 18mm slim design 1×SPDT 16A @ 250V AC 0% Setting Deviation IP40 Front
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FCV18-01 Voltage Control Relay with Manual Reset
🛡️ Over & Under Voltage Protection Independent adjustable thresholds protect equipment from both high and low voltage conditions.
🤚 Manual Reset Function Output remains off after a fault clears until manually acknowledged — critical for safety-sensitive applications.
🎯 ≤1% Measurement Accuracy High-precision voltage detection with ≤1% or ±1V accuracy ensures reliable tripping decisions every time.
⚡ 12–240V Universal Supply Voltage AC/DC supply on A1-A2 — one relay covers virtually all control panel power sources worldwide.
📏 18mm Ultra-Slim Housing Same compact form factor as the FCT18 and FCP18 series — saves valuable DIN rail space.
🔧 1×10⁷ Mechanical Life Exceptional durability with 1×10⁷ mechanical operations for demanding applications.

📋 Models & Ordering

Model Monitoring Voltage Voltage Type Reset Mode Supply Voltage Datasheet
FCV18-01A240 65–260V AC Manual 12–240V AC/DC 📄 Download PDF
FCV18-01A220 165–260V AC Manual 12–240V AC/DC 📄 Download PDF
FCV18-01A48 20–80V AC Manual 12–240V AC/DC 📄 Download PDF
FCV18-01D240 65–260V DC Manual 12–240V AC/DC 📄 Download PDF
FCV18-01D48 20–80V DC Manual 12–240V AC/DC 📄 Download PDF
FCV18-01D12 9–18V DC Manual 12–240V AC/DC 📄 Download PDF

💡 Model selection guide: Choose A prefix for AC voltage monitoring, D prefix for DC voltage monitoring. The number indicates the nominal monitoring voltage range. All models share the same 12–240V AC/DC supply on A1-A2 terminals, manual reset function, and digital push-button parameter setting.

⚙️ Technical Specifications

🔌 Supply

Supply TerminalsA1 – A2
Supply Voltage12–240V AC/DC
Power ConsumptionAC 3.5VA / DC 2.0W
Voltage Tolerance-15% ~ +10%

🛡️ Monitoring Function

FunctionOver & Under Voltage Protection
Reset ModeManual Reset
Monitoring TerminalsS1 – S2
Setting Accuracy0% – Digital Setting
Measurement Accuracy≤1% / ±1V
Time DelayAdjustable via button

🔌 Output

Contact1 × SPDT
Rated Current16A @ 250V AC
Mechanical Life1×10⁷ operations
Electrical Life1×10⁵ operations

📐 Physical & Environmental

Dimensions18 × 90 × 64 mm
MountingDIN rail EN 60715
Protection DegreeIP40 (front) / IP10 (terminals)
Operating Temp.-20°C ~ +55°C
Storage Temp.-30°C ~ +70°C

📜 Standards & Certifications

ComplianceGB/T 14048.5, IEC 60947-5-1, EN 6812-1
Contact ConfigurationSPDT: 11(COM)-12(NC)-14(NO)
Pollution Degree2
Max. Cable SizeAWG 13–20 / 0.4 N·m

💡 Panel LED Indicators

LED Color Status Meaning
Un Green OFF Supply voltage not applied
Un Green ON Supply voltage applied
R Red OFF NC (11-12) contact closed
R Red ON NO (11-14) contact closed

📈 Function Diagram – Overvoltage & Undervoltage Protection

FCV18-01 Overvoltage and Undervoltage Protection Function Diagram

• The relay monitors single-phase voltage via terminals S1–S2.
• When supply voltage A1-A2 is applied and the monitored voltage is within the set thresholds, the output relay R closes (NO contact 11-14 makes).
• If voltage goes above the overvoltage threshold, the output relay R opens after the set time delay to protect connected equipment.
• If voltage drops below the undervoltage threshold, the output relay R opens after the set time delay.
• Manual Reset: After a fault clears, the output relay remains open even when voltage returns to normal. The operator must either press and hold the button or cycle the supply power to reset the relay. This prevents automatic restart of machinery after a voltage event.

🎬 See it in Action

🔧 Wiring & Terminal Layout

Terminal Identification

A1 — Supply L / + A2 — Supply N / - S1 — Voltage Input (+) S2 — Voltage Input (-) 11 — COM 12 — NC 14 — NO
⚠️ 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.

Supply (A1–A2): Connect to 12–240V AC/DC. This powers the relay's internal electronics.
Monitoring (S1–S2): Connect the voltage to be monitored. For AC, polarity is not critical. For DC models, observe polarity.
Output (11-12-14): SPDT contact rated 16A @ 250V AC. Wire in series with the load contactor or protection circuit.

FCV18-01 Wiring and Terminal Layout Diagram

🛠️ Parameter Setting Guide

  1. Enter Parameter Setting Mode: Press and hold the button until the LED starts flashing. This indicates you have entered the configuration mode.
  2. Set Overvoltage Threshold (U>): Use the button to set the upper voltage limit. When the monitored voltage exceeds this value, the relay will trip after the time delay.
  3. Set Undervoltage Threshold (U<): Configure the lower voltage limit. When the monitored voltage drops below this value, the relay will trip after the time delay.
  4. Set Time Delay: Adjust the time delay from the available range. This delay applies before the output opens on voltage faults and before the initial closure on power-up.
  5. 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 after a power cycle.

🏭 Typical Applications

⚡ Generator Protection
Prevents equipment damage from generator voltage excursions — manual reset ensures operator inspection
🔧 Machine Tools
Protects CNC and precision machines where automatic restart after a fault is unsafe
💡 Lighting Systems
Prevents lamp and ballast damage from sustained overvoltage conditions
🔋 Battery Systems
Monitors DC battery voltage — protects against overcharge and deep discharge
🏗️ HVAC Equipment
Safeguards compressors and fan motors from voltage-related failures
📡 Telecom Equipment
Protects sensitive communication gear from DC supply voltage anomalies

🔗 Related Products

Explore other voltage monitoring relays in the FCV18 series:

FCV18-01 — Voltage Relay Manual Reset FCV18-02 — Voltage Relay Auto Reset

❓ Frequently Asked Questions

🔹 What does Manual Reset mean?
With manual reset, once a voltage fault causes the output relay to open, it remains open even after the voltage returns to normal. To reset, the operator must either press and hold the button or cycle the A1-A2 supply power. This is critical for safety applications where automatic restart could be dangerous.
🔹 What is the difference between FCV18-01 and FCV18-02?
The only difference is the reset mode. FCV18-01 uses manual reset — the output stays off after a fault until the operator intervenes. FCV18-02 uses auto reset — the output automatically re-closes when voltage returns to normal. Choose based on your safety requirements.
🔹 How accurate is the voltage measurement?
The FCV18-01 provides ≤1% or ±1V measurement accuracy, whichever is greater. Combined with 0% digital setting deviation, this ensures precise and repeatable voltage monitoring.
🔹 Can I monitor both AC and DC voltages with the same model?
No. Each sub-model is designed for either AC only (A prefix) or DC only (D prefix). Choose the appropriate model for your application voltage type. The supply voltage on A1-A2 is always 12–240V AC/DC for all models.
🔹 What monitoring voltage ranges are available?
AC models: 65–260V (A240), 165–260V (A220), 20–80V (A48). DC models: 65–260V (D240), 20–80V (D48), 9–18V (D12). Select the model whose monitoring range covers your nominal operating voltage.
🔹 What is the mechanical life of the output contacts?
The relay has an outstanding mechanical life of 1×10⁷ operations. Electrical life is 1×10⁵ operations at rated 16A/250V AC load.

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