Description
1. Product Overview
2. Key Features
Three‑Phase Differential Protection: Compares both ends of each phase winding (CT inputs)DEIF.
Ultra‑Fast Response: <50 ms operating time (instantaneous, no intentional delay)DEIF.
Adjustable Differential Threshold (I>>): 100–400% of CT secondary rated current (1 A or 5 A)DEIF.
Dual Relay Outputs: 2 sets of parallel contacts (NO/COM/NC) for trip/alarm redundancyDEIF.
LED Status Indicators: POWER and DIFF CURRENT LEDs for immediate status.
Wide Auxiliary Supply: 24 VDC ±20% or 110/230 VAC ±10%.
Isolation: 3250 VAC isolation between inputs, outputs, and supply.
DIN‑Rail or Surface Mount: Compact Uni‑line housing.
Certifications: CE, IEC 60945 (marine), DNV/GL, ABS, LR, CCS.
Conformal Coating: Withstands humidity, dust, and corrosive environments.
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Model | RMC‑131D (Differential Current Relay, I>>) |
| Manufacturer | DEIF A/S |
| Part Number | 4921240140 (standard) |
| CT Inputs (Differential) | |
| – Rated Current | 1 A or 5 A (selectable via internal jumper)DEIF |
| – Input Burden | ≤0.5 VA per phase |
| – Frequency | 50/60 Hz ±5% |
| – Measurement | RMS (sinusoidal); peak‑processed for speedDEIF |
| Differential Trip (I>>) | |
| – Threshold | 100–400% In (adjustable via potentiometer)DEIF |
| – Response Time | <50 ms (instantaneous)DEIF |
| – Accuracy | ±5% of set value |
| Auxiliary Supply | |
| – DC | 24 VDC ±20% (18–30 VDC), ≤2 W |
| – AC (Optional) | 110/230 VAC ±10%, 50/60 Hz, ≤3.5 VA |
| – Fusing | 1 A slow‑blow (internal) |
| Relay Outputs | |
| – Configuration | 2× NO/COM/NC (parallel, redundant)DEIF |
| – Rating | 250 VAC / 8 A (resistive); 30 VDC / 8 A |
| – Mechanical Life | ≥100,000 operations |
| – Isolation | 3250 VAC / 1 min (inputs‑outputs‑supply) |
3.2 Environmental & Mechanical
| Parameter | Specification |
|---|---|
| Operating Temperature | –20 °C to +60 °C (marine: –30 °C to +60 °C) |
| Storage Temperature | –40 °C to +85 °C |
| Humidity | 5–95% RH non‑condensing |
| Vibration | 2–13.2 Hz: ±0.7 mm; 13.2–100 Hz: ±0.5 g |
| Enclosure | IP20 (front/terminals); conformal coated PCB |
| Dimensions (W×H×D) | 75 × 105 × 55 mm (4TE) |
| Weight | Approx. 0.48 kg |
| Mounting | 35 mm DIN rail (horizontal/vertical) or surface |
4. Application Scope
Generator Winding Protection: Internal short circuits and leakage currents (marine/industrial)DEIF.
Motor Differential Protection: Large AC motors (pumps, fans, compressors).
Transformer Windings: Primary/secondary internal fault detection.
Marine Switchboards: Shipboard generators (IEC 60945 certified).
Industrial MCCs & Panels: Critical asset differential protection.
Retrofit Projects: Upgrade legacy differential schemes with fast, reliable I>> protection.
5. Installation & Wiring
5.1 Installation Requirements
Mounting: 35 mm DIN rail (preferred) or surface; ≥25 mm clearance top/bottom.
Environment: Avoid direct sunlight, moisture, corrosive gases, excessive vibration.
ESD Protection: Anti‑static wristband/grounded mat (static‑sensitive PCB).
Cable Separation: CT input cables away from auxiliary supply cables (≥5 cm).
5.2 Terminal Wiring (Simplified)
| Terminal | Description | Wire Gauge |
|---|---|---|
| CT Inputs (Line Side, L1/L2/L3) | ||
| 1–2 | L1 CT (Line) | 2.5 mm² (twisted‑pair) |
| 3–4 | L2 CT (Line) | 2.5 mm² (twisted‑pair) |
| 5–6 | L3 CT (Line) | 2.5 mm² (twisted‑pair) |
| CT Inputs (Neutral Side, L1/L2/L3) | ||
| 7–8 | L1 CT (Neutral) | 2.5 mm² (twisted‑pair) |
| 9–10 | L2 CT (Neutral) | 2.5 mm² (twisted‑pair) |
| 11–12 | L3 CT (Neutral) | 2.5 mm² (twisted‑pair) |
| Auxiliary Supply | ||
| 13–14 | 24 VDC (+/−) or 110/230 VAC | 1.5 mm² |
| 15 | Chassis ground (PE) | 2.5 mm² |
| Relay Outputs (2 Sets, Parallel) | ||
| 16–17–18 | Output 1: NO/COM/NC | 1.5 mm² |
| 19–20–21 | Output 2: NO/COM/NC | 1.5 mm² |
CT Polarity: Strictly match polarities (line vs neutral ends); never open CT secondary with primary current (lethal voltage)DEIF.
Shielding: Shielded twisted‑pair for CTs; ground shield at RMC‑131D end only.
Terminal Torque: 0.6–0.8 Nm (prevent looseness/overheating).
Fusing: Auxiliary supply: 1 A slow‑blow; CT inputs: no external fusing.
5.3 Jumper Settings
CT Ratio (J1): 1 A or 5 A (match system CT secondary)DEIF.
6. Front Panel & Operation
6.1 Front Panel Layout
LED Indicators
POWER: On = Auxiliary supply OK.
DIFF CURRENT: On = Differential fault detected (relay tripped).
Adjustment Potentiometer
I>> ADJ: 100–400% In (differential trip threshold)DEIF.
6.2 Startup & Configuration
Mounting & Wiring: Install DIN‑rail; wire CTs (line/neutral), supply, outputs.
CT Ratio: Set J1 to 1 A or 5 ADEIF.
Power On: Apply supply; POWER LED on.
Set Threshold:
Calculate: I>> = (Desired Differential Trip Current / CT Secondary Rated Current) × 100%.
Adjust I>> ADJ (100–400% In). Example: 5 A CT, trip at 15 A differential → 300%.
Output Wiring: Connect NO/COM to trip breaker/alarm (dual outputs for redundancy).
6.3 Normal Operation
POWER: Solid green (supply healthy).
DIFF CURRENT: Off (no fault).
Relays: De‑energized (NO open, NC closed).
6.4 Fault Operation (Differential Current)
DIFF CURRENT: Solid red (fault detected).
Relays: Energized (NO closes, NC opens → trips breaker/alarm).
Reset: Remove fault; auto‑reset (LED off, relays de‑energized).
7. Safety Precautions
High Voltage Hazard: Only qualified electrical personnel to install/service. Disconnect all sources (supply + CT primary) before wiringDEIF.
CT Overvoltage Risk: Never open CT secondary with primary current (lethal voltage); short CTs before connecting/disconnectingDEIF.
ESD Sensitivity: Static damage to PCB; use anti‑static gear.
Relay Ratings: Do not exceed 250 VAC/8 A; suppress inductive loads.
No Unauthorised Modification: Tampering voids warranty and risks unsafe operationDEIF.
Environmental Limits: Operate only –20 °C to +60 °C (standard) or –30 °C to +60 °C (marine).
8. Maintenance & Storage
8.1 Regular Maintenance (Every 12 Months)
Visual Inspection: Loose terminals, damaged wiring, corrosion, discoloration.
Cleaning: Dry lint‑free cloth; no liquid cleaners.
LED Check: Verify POWER/DIFF CURRENT operation.
Terminal Tightness: Retorque to 0.6–0.8 Nm.
Functional Test: Inject differential current > set threshold; verify LED and outputsDEIF.
Insulation Resistance: CT inputs to ground ≥1 MΩ @ 500 VDC.
8.2 Storage Guidelines
Packaging: Original anti‑static packaging + desiccant.
Environment: 10–30 °C, 30–70% RH, dry/clean/dust‑free.
Protection: Avoid direct sunlight, extremes, shock/vibration.
Duration: Shelf life ≤5 years; inspect/test before use if stored longer.
9. Troubleshooting
| Fault Phenomenon | Possible Cause | Solution |
|---|---|---|
| POWER LED Off | No supply / blown internal fuse | Check wiring; replace 1 A fuse. |
| DIFF CURRENT LED On (No Fault) | CT mismatch/wiring error / threshold too low | Check CT polarities/wiring; increase I>>. |
| No Trip on Differential Fault | Threshold too high / CT ratio mismatch / relay fault | Lower I>>; correct J1; test/replace relay. |
| Relay Chatters | Loose wiring / unstable supply | Retorque terminals; stabilize voltage. |
| CT Input Burnout | CT secondary open with primary current | Never open CT secondary; short before wiringDEIF. |
10. Warranty & Disclaimer
Model: RMC‑131D Differential Current Protection RelayDEIF.
Warranty Period: 24 months from delivery (normal installation/use per manual).
Warranty Exclusions: Misuse, overvoltage, lightning, water ingress, unauthorised modification, improper maintenance, CT/VT faultsDEIF.
Specifications Subject to Change: Manufacturer reserves the right to update specifications without prior noticeDEIF.
Liability Limitation: Manufacturer is not liable for indirect/consequential damages (downtime, lost revenue, equipment damage)DEIF.
Documentation Version: 1.0 (2026); latest manual at www.deif.comDEIF.
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