Schneider EOCRSSD-05S Comprehensive Motor Protection Relay

Aufschlüsselung des Modellcodes

1. EOCR: Electronic Over-Current Relay for Motor Comprehensive Protection (Originally SAMWHA from South Korea, now integrated into Schneider Electric)
2. SSD: Digital Display Version (vs. basic SS model without display)
3. 05: Current detection range 0.5～6A
4. S: Wide-range control power supply type 24～240V AC/DC; W variant in the same series supports high voltage 380～440VAC
5. Grundlegende elektrische Spezifikationen

III. Three Core Protection Functions (Fault Code Display)

1. OC Overcurrent / Überlastschutz

Trips when the motor operates continuously above rated current beyond the preset O-Time duration; Recommended setting: 110%～125% of motor rated current.

2. PL Phase Loss Protection

Cuts off the contactor within 3 seconds if any phase of three-phase power supply is lost, preventing unbalanced winding burnout of the motor.

3. LC Locked Rotor Protection

Detects rotor jamming or load seizure during startup when current surges to 3× the set value, and triggers fast shutdown after D-Time delay.

1. Front Panel DIP Switches & Button Instructions
2. LOAD(A) Knopf: Calibrate rated motor protection current (continuously adjustable from 0.5～6A)
3. D-TIME: Delay to bypass high startup current; set 5～10s for fans/water pumps, 15～30s for heavy-duty compressors
4. O-ZEIT: Overload trip delay during normal operation; 1s for light loads, 5～10s for heavy loads
5. DIP Switch Bank

3P: 3-phase motor mode (factory default)

1P: Single-phase motor mode; live wire and neutral wire pass through two through-hole CTs separately

N/R: Contact mode switch

N (Ausfallsicher): Terminals 95-96 are normally closed under normal operation; opens upon fault to break the contactor coil circuit (mainstream wiring scheme)

R (Non-Fail-Safe): Terminals 97-98 are normally open under normal operation; closes upon fault to output alarm signals

5. TEST Self-test Button: Simulate overcurrent fault to verify continuity of the relay and control circuit
6. RESET Reset Button: Manual reset after fault tripping
7. Standard Wiring Rules
8. Direct Measurement via Built-in CT (Motor Rated Current ≤6A, No External CT Required)
9. Control power: Connect 24～240V AC/DC power to terminals A1 and A2
10. Hauptstromkreis: Run two motor phase cables through the upper two through-hole cores (current flows in the same direction)
11. Main control circuit: Wire the contactor coil in series with 95-96 Öffnerkontakte (N mode)
12. Alarm circuit: Connect fault indicator lamp / alarm buzzer to 97-98 KEINE Kontakte
13. High-Current Extension Scheme (Motor Rated Current ＞6A, External 5A CT Required)

Route the 5A secondary signal wires of external CT through the relay’s through-hole cores;

Calibration Formula: LOAD set value of relay = Motor rated current ÷ CT transformation ratio

Beispiel: 80A motor matched with 100/5A CT (ratio=20) → Set LOAD knob to 4A

1. Anwendbare Szenarien
2. Low-power 3-phase motors: 0.15～3kW fans, Wasserpumpen, Förderer, Präzisionswerkzeugmaschinen
3. Single-phase equipment: Einphasige Wasserpumpen, small air compressors (switch to 1P mode via DIP switch)
4. VFD-driven equipment (20～200Hz), superior anti-interference performance vs. basic SS model
5. Direct replacement for traditional bimetallic thermal overload relays and legacy EOCR-SS-05S (same footprint, no cabinet modification needed)

VII. Cross-Series Model Selection Comparison

VIII. Standard Commissioning Procedures

1. Route main circuit cables through CT cores, apply power to A1/A2; digital tube displays real-time operating current
2. Adjust LOAD knob to 1.1～1.25× motor rated current
3. Set D-Time to match actual motor startup duration to avoid false tripping from high inrush startup current
4. Configure O-Time according to load thermal withstand capability
5. Long-press TEST button for self-test; confirm reliable contactor cut-off and OC fault code display on panel
6. Simulate phase loss test; verify trip within 3s with PL code displayed, fault record retained without data loss after power cycle
7. Key Troubleshooting Guidelines
8. No display after power-on: Check supply voltage at A1/A2 and loose terminal connections
9. Instant tripping upon motor startup: D-Time delay set too short; mechanical rotor jamming; phase loss fault
10. Tripping after prolonged operation: LOAD setting value too low; Motorüberlastung; schlechte Wärmeableitung
11. No phase loss protection triggered: DIP switch accidentally switched to 1P single-phase mode; only one cable passed through CT cores

Schneider EOCRSSD-05S (0.5～6A Range) Segmented Application Scenarios

1. Matched Motor Power Range

Rated detection current: 0.5～6A, corresponding to 380V three-phase motors: 0.15kW～3kW; 220V single-phase motors ≤1.5kW. Built-in through-hole CT eliminates external current transformers for compact cabinet installation.

1. General Industrial Standard Applications
2. Small Conveying & Transmission Equipment

Mini belt conveyors on assembly lines, micro roller conveyors, small distributing feeders

Micro conveyor belts for packaging machinery, label transport motors, small material sorting motors

Protection requirements: Locked rotor protection for material jamming, phase loss burnout prevention, light-load overload protection

2. Lüfter & Lüftungssysteme

Cabinet cooling fans, small centrifugal fans, laboratory exhaust fans, air purification unit fans

Micro circulation fans for central air conditioning, auxiliary small cooling tower fans

Eigenschaften: Smooth startup current; D-Time delay set to 5～10s suffices; windings highly vulnerable to burnout under phase loss conditions

3. Wasserpumpen & Small Hydraulic Pump Stations

Small clean water pumps, metered chemical dosing pumps, machine tool cooling pumps, laboratory circulation pumps

Micro hydraulic station oil pumps, lubrication gear pumps

Suitable protection: Dry-run overload protection, impeller seizure locked rotor protection, three-phase phase loss fault protection

4. Auxiliary Equipment for Machine Tools

Machine tool cooling pumps, tool lubrication pumps, small chip conveyor motors, bench grinders, miniature polishers

Built-in micro drive motors for CNC equipment

Vorteile: Supports 20～200Hz variable frequency motors; can be directly installed on VFD output terminals with strong anti-interference capability

III. HVAC, Air Purification & Wasseraufbereitungsindustrie

1. Booster pumps for water purification equipment, small chemical dosing mixing motors
2. Micro air supply motors for fresh air systems, circulation fans of air purification units
3. Small swimming pool circulation pumps, Abwasserhebepumpen
4. Mixer motors for lab constant-temperature equipment, small vacuum pumps
5. Lebensmittelverpackung & Light Industry Equipment
6. Small sealing machines, micro mixing motors for filling equipment, micro conveyor drives
7. Micro distributing motors for candy & biscuit production lines
8. Small blenders and homogenizers (0.15～3kW)

Pain point: Material jamming leads to locked rotor; SSD series rapidly detects 3× rated locked rotor current and triggers trip

1. Small Loads Inside Automation Integrated Control Cabinets
2. Cooling fans for PLC cabinets and VFD cabinets
3. Micro actuator motors matched with valve islands, drive motors for electric regulating valves
4. Small electric actuators, electric air damper actuators
5. Local control boxes for ventilation & plumbing in smart buildings

Vorteile: Compact DIN rail mounting; wide 24～240V AC/DC power supply, compatible with 24VDC control cabinets directly

1. Plastik, Gummi & Printing Small Machinery
2. Small paper feed motors, micro take-up motors for printing presses
3. Feeder motors for auxiliary extrusion equipment, low-power plastic shredders
4. Micro traction motors for film slitting machines

VII. Motors Supporting Laboratory & Medizinische Ausrüstung

1. Small drive motors for mixing & centrifugation in biochemical instruments
2. Medical purification fans, small water circulation equipment
3. Laboratory vacuum pumps, small stirring devices

Eigenschaften: High-precision delicate equipment; dual protection against phase loss and overload to avoid equipment scrapping caused by motor burnout

VIII. Dedicated Single-Phase Application Scenarios (Switch to 1P via DIP Switch)

220V single-phase cooling water pumps, small single-phase air compressors

Inländisch / commercial small single-phase circulation fans, single-phase mixing motors

Small single-phase electric valve actuators

1. Dedicated VFD-Driven Scenarios

For 0.15～3kW motors driven by VFD output terminals; supports variable frequency current detection at 20～200Hz, immune to carrier frequency interference:

1. Small variable-frequency cooling pumps, variable-speed ventilation fans
2. Small variable-speed conveying equipment
3. Ungeeignete Anwendungsszenarien (Vermeidung von Auswahlfallen)
4. Motor rated current ＞6A (EOCRSSD-30S/60S required)
5. High-power air compressors, water pumps and fans above 5kW
6. Heavy-duty equipment with frequent shock loads (z.B., large crushers)
7. Sealed high-temperature enclosures without heat dissipation (ambient temperature exceeding -20～60℃)
8. Hazardous explosive areas: Keine explosionsgeschützte Zertifizierung; cannot be directly deployed in explosive hazardous locations

Summary of Selection & Anwendungsvorteile

EOCRSSD-05S is a universal protection relay for low-power motors, serving as a direct replacement for legacy thermal overload relays. It integrates digital real-time current display, Phasenverlust, locked rotor and overload all-in-one protection. Its wide AC/DC power input fits 24VDC control cabinets, 220V local control boxes and 380V main control cabinets. With standard 35mm DIN rail mounting, it is the preferred choice for compact integrated cabinet projects.