Schneider 3-pole main contacts LC1D38BD

Schneider TeSys Deca series, 3-Polhauptkontakte, 24VDC-Spule. Designed for motor start/stop, HVAC and automation control cabinets. Eingebaute 1NO+1NC-Hilfskontakte.

✅ Model Code Definition

LC1: Standardschütz

D: TeSys D (Deka) Serie

38: Rated operational current 38A @ AC-3, 400V

BD: 24V DC-Spule (integrated coil surge suppression)

📌 Key Electrical Specifications

🛠️ Typical Applications

Direct-on-line, star-delta and forward/reverse control of 3-phase asynchronous motors

HVAC-Systeme, Wasserpumpen, Fans, Luftkompressoren

Automatisierungsausrüstung, packaging machinery and production line control cabinets

Direct coil drive by PLC 24VDC digital outputs (no intermediate relay required)

🧩 Compatible Accessories

Thermisches Überlastrelais: LRD-Serie (LRD35…), snap-fit directly below the contactor

Auxiliary contact block: LA1DN (for extra NO/NC contacts)

Mechanisches Verriegelungsmodul: LA9D4001 (for forward/reverse interlock)

Überspannungsunterdrückung: Integrated inside coil, no external component needed

🔁 Alternative & Compatible Selection

1. AC coil variants within the same series: LC1D38M7 (220VAC), LC1D38B7 (24VAC)
2. Inländische Alternative: CJX2-3811 DC24V (note differences in dimension, terminals and mechanical life)

⚠️ Wichtig: BD = 24VDC, B7 = 24VAC. Coils are NOT interchangeable.

📋 Certifications & Standards

IEC 60947-1/-2/-4-1, CCC, cULus. Complies with IEC60335-1 flame retardant standard and A2L refrigerant safety certification for HVAC.

🧪 Second-hand Inspection Checklist

1. Spule: Continuity check on A1/A2. Apply 24VDC; armature pulls in without noise or overheating.
2. Hauptkontakte: L1/L2/L3 ↔ T1/T2/T3. Conductive when closed, high resistance when open; inspect contact erosion.
3. Hilfskontakte: 13-14(NEIN), 21-22(NC). Switch synchronously with main contacts.
4. Mechanisch: Kein Kleben; housing free of cracks or carbon blackening.

HS Code Reference

8536410000 (Electromagnetic contactor, voltage ≤60V)

Typical Engineering Application Cases for LC1D38BD

Core advantages: DC24V-Spule, direct PLC drive without intermediate relay; built-in surge suppression and certified mirror NC contact; 18.5kW max 3-phase motor @ AC-3, 50A for AC-1 resistive loads

Fall 1: Chilled water pump DOL start for HVAC BMS (Gebäudeautomationssystem)

Laden: 15kW 3-phase chilled water pump, 380V, motor rated current ≈28A

Control scheme: SPS (Siemens / Schneider M241) DO directly drives LC1D38BD 24VDC coil

Hauptstromkreis: 3P circuit breaker → LC1D38BD → LRD35 thermal overload relay → pump motor

Steuerlogik: BMS outputs 24VDC based on water temperature/pressure differential to energize contactor and start pump. Built-in 1NO auxiliary contact feeds running status back to PLC; built-in mirror NC contact for fault acquisition.

Selection rationale: DC coil provides strong anti-interference. BMS cabinets commonly adopt DC24V control. Wide temperature range -5~+60℃ suits high-temperature equipment rooms. 45mm narrow body saves cabinet space.

Zubehör: LRD35 thermal relay (28~36A), DIN-Schienenmontage.

Fall 2: Air compressor motor control (OEM machinery manufacturer)

Laden: 18.5kW screw air compressor main motor, 400V

Control scheme: PLC directly drives LC1D38BD with pressure switch interlock for shutdown

Schaltung: Circuit breaker → LC1D38BD → LRD thermal relay → air compressor motor

Merkmale: Häufiges Start-Stopp (max 3600 Zyklen/Stunde). DC coil pulls in stably without AC hum. Built-in coil surge suppression protects PLC output points against back EMF.

Notiz: AC-3 operation reaches the 38A rating limit. Derating evaluation is recommended for heavy-duty frequent cycling.

Fall 3: Water treatment — duty/standby mutual interlock control cabinet for sewage lift pumps

Laden: Two 15kW sewage pumps, duty-standby auto-switching by liquid level

Konfiguration: 2 × LC1D38BD + LA9D4001 mechanical interlock module

Logik: Pump starts on high liquid level. If main pump trips (thermal relay fault), PLC automatically switches to standby pump. Mechanical interlock prevents simultaneous closure and short circuit.

Safety feature: Built-in mirror NC contact for safety loop and fault diagnosis, meeting water treatment control cabinet safety specifications.

Anwendung: Municipal sewage, factory circulating water, rainwater lift pumping stations.

Fall 4: Forward/reverse circuit for conveyor motors in packaging machinery / Produktionslinien

Laden: 11~15kW belt conveyor motor requiring forward and reverse rotation

Konfiguration: 2 × LC1D38BD (KM1 forward, KM2 reverse) + LA9D4001 mechanical interlock

Kontrolle: PLC 24VDC digital outputs drive each contactor coil separately. Electrical interlock (using built-in NC auxiliary contacts) plus mechanical interlock provides double protection to prevent power short circuit.

Vorteil: DC coil has better EMI immunity than AC coils in workshops dense with inverters and sensors, reducing accidental pull-in faults.

Fall 5: Star-delta reduced voltage starting for 18.5kW dust extraction fan

Laden: 18.5kW dust removal fan with high inrush current, star-delta starting adopted

Konfiguration: 3 × LC1D38BD, serving as main contactor, star contactor and delta contactor respectively

Logik: PLC outputs 24VDC sequential control; star reduced-voltage start first, then time-delayed switch to delta full-voltage operation. Built-in contactor auxiliary contacts provide status feedback and electrical interlock.

Notiz: High inrush current occurs at delta switching in star-delta circuits; contact life must be reviewed.

Fall 6: AC-1 resistive load: Industrial heating module control

Laden: 3-phase heating elements, total resistive load ≤33kW (AC-1 50A @400V)

Besonderheit: Resistive load has no starting inrush current. AC-1 rated 50A capacity higher than motor duty. PLC 24V DO directly controls heating circuit on/off.

Anwendung: Öfen, constant temperature units, process heating equipment.

Fall 7: Cleanroom air handling unit for medical facilities (medical HVAC)

Laden: 15kW supply air fan for operating room clean air conditioning

Merkmale: Medical equipment demands high reliability and low EMI. LC1D38BD DC coil with built-in surge suppression, no electromagnetic noise from AC coils. Complies with IEC60335 HVAC safety standard, suitable for A2L refrigerant HVAC equipment, widely used in hospital BMS control cabinets.

Allgemeine Auswahl & Construction Key Points (Valid for All Cases)

1. DC coil critical note: BD = 24VDC, MUST NOT be connected to AC24V. PLC output capacity must meet coil power consumption (~15VA).
2. Hilfskontakte: Built-in 1NO (running feedback) +1NC (mirror safety contact, NOT for normal latching). Add LA1DN auxiliary contact block for more contacts.
3. Überlastschutz: Must be fitted with LRD thermal overload relay, set per motor nameplate current and shall not exceed motor rated current.
4. Utilisation category distinction

AC-3 (normaler Motor Start-Stopp): 38A, max 18.5kW @400V

AC-1 (pure resistive heating): 50A

AC-4 (frequent jogging, plug braking): Derating erforderlich

Not Suitable Applications

Direct-on-line starting of 3-phase motors above 18.5kW (AC-3)

High-power capacitor switching (use dedicated LC1DxxKQ capacitor contactors)

Explosionsgefährdete Bereiche (explosion-proof series required)

LC1D38BD (TeSys D DC Coil) Gliederung & Montagemaße

Without attached accessories (Hilfskontakte, Thermorelais, mechanische Verriegelung), DC-Spulenversion

Umrissmaße (B × H × T)

45 mm × 85 mm × 92 mm

Breite: 45mm (DIN rail module, 1 module unit)

Höhe: 85mm

Tiefe: 92mm (from mounting backplate to front face)

Panel screw mounting holes (DC coil specific, round holes for M4)

Horizontal center distance between two holes: 35 mm

Vertical center distance between two holes: 70 mm

Screw size: M4, two round holes (⚠️ AC coil LC1D38M7 uses slotted holes; mounting layout differs from BD DC version)

Schienenmontage

Kompatibel mit standardmäßiger 35-mm-DIN-Schiene (TH35-7,5), clip-on installation, no drilling required.

Cabinet Layout Recommendations

1. Mounting LRD thermal relay at bottom: overall height increases; reserve adequate clearance.
2. Mounting LA1DN auxiliary contact block on top: extra depth and height required.
3. Multiple contactors side-by-side: 45mm Breite, can be mounted tightly on rail without gap. Reserve heat dissipation gap for high-temperature environments.

Operating Principle of Schneider LC1D38BD Contactor

LC1D38BD is an electromagnetic contactor with DC coil (TeSys D-Serie). Im Wesentlichen, it is a remotely controlled electrical switch driven by 24VDC electromagnet, using low DC signal to switch high-power 3-phase main circuit.

1. Grundstruktur
2. Electromagnetic actuation section (Coil A1/A2): 24V DC excitation coil, fixed core, moving armature, Rückholfeder
3. Hauptkontakte (power circuit L1/L2/L3 → T1/T2/T3): 3 pairs of normally-open main contacts, rated 38A AC-3, carrying high current for 3-phase motors / heating loads
4. Hilfskontakte (Signalrückmeldung): Built-in 1NO (13-14)+1NC (21-22) mirror auxiliary contacts for status feedback and electrical interlock
5. Arc chamber: Extinguishes electric arc when main contacts open, protecting contacts from rapid erosion

✅ Key feature for BD model: DC coil with integrated surge suppressor.

2. Full Operating Sequence

2.1 Coil Energized (Pull-in action)

Apply DC24V to A1 and A2 via PLC or external control circuit:

DC coil generates constant magnetic field, magnetizing fixed core, overcoming return spring force and pulling in moving armature.

Armature drives contact carrier synchronously:

3 pairs of main NO contacts close → 3-phase main circuit energized, motor/load powered on

Auxiliary contacts switch simultaneously: 13-14(NEIN) schließt; 21-22(NC) öffnet sich

Characteristic of DC coil: constant current after pull-in, no vibration or hum from AC coils.

2.2 Coil De-energized (Drop-out action)

DC24V control signal removed:

Magnetic field of coil disappears, return spring pulls armature back.

All main contacts open, cutting high-current main circuit.

Auxiliary contacts reset: 13-14(NEIN) öffnet sich; 21-22(NC) restores closed state.

Built-in surge suppression absorbs back EMF generated at coil de-energization, protecting upstream PLC output points.

3. Core Differences Between DC Coil (BD) and Conventional AC Coil
4. Wechselstromspule: operates on alternating magnetic field, prone to vibration and hum; hoher Einschaltstrom; contact bounce under voltage fluctuation.
5. LC1D38BD DC24V coil:

Stable magnetic field, armature free of vibration, quiet operation

Pull-in current ≈ holding current, geringer Einschaltstrom

Built-in freewheeling suppression, ideal for direct PLC DO drive

Nachteil: Must never connect to AC supply; AC input burns coil immediately.

4. Typical Functions of Auxiliary Contacts

1NEIN (13-14): Running status feedback to PLC to detect contactor pull-in state

1NC (21-22, mirror contact): Safety circuits, fault detection, electrical interlock (forward/reverse circuits)

⚠️ Mirror contact property: NC contact cannot close when main contacts are welded shut, complying with safety circuit requirements.

5. Mandatory Protection Logic for Engineering

The contactor only performs switching and has NO overload protection:

Fit LRD thermal overload relay in main circuit: on motor overload, thermal relay NC contact opens contactor coil circuit to cut motor power.

Circuit breaker installed upstream: fast short-circuit protection for main power supply.

One-sentence summary:

Apply DC24V to A1/A2; electromagnetic force actuates internal contacts to close high-power 3-phase main circuit. Remove 24V supply; spring resets and opens main circuit. Low-voltage 24V signal remotely switches high-power loads. Auxiliary contacts provide status feedback and safety interlock.