Wieland SNA-4053-K-A Safety Relay

SNA: Safety switch monitoring series (for monitoring emergency stop, cancelli di sicurezza, safety light curtains)

4053: Codice specifica

K: Pluggable screw terminals

UN: Supply voltage AC/DC 24 V

Suffix differentiation for the series:

A = AC/DC 24 V; C = Push-in spring terminals; KM = Automatic reset; KE = Special version

2. Specifiche principali & Safety Ratings
3. Certificazioni di sicurezza

PL e / Categoria 4 (NELL'ISO 13849-1)

SIL CL3 (IN 62061)

2. Configurazione dei contatti

3 safety normally open contacts (13-14 / 23-24 / 33-34)

1 normally closed signal contact (41-42)

3. Dati elettrici

Fornitura: 24 V CA/CC

Continuous rated current Ith: 8 UN

AC-15: 230 V / 5 UN; DC-13: 24 V / 5 UN

Montaggio: DA 35 guida da mm; Larghezza 22.5 mm

4. Input Functions

Dual-channel safety circuit (S11/S12, S21/S22)

Supports cross-channel short-circuit monitoring

Ripristino manuale (with reset monitoring)

Adatto per: Emergency stop buttons, interruttori dei cancelli di sicurezza, interruttori magnetici di sicurezza, safety light curtains

3. Typical Wiring Logic
4. A1(+), A2(-): 24 Alimentazione V
5. S11-S12, S21-S22: Dual-channel safety devices (normally closed signal)
6. S33-S34: Reset terminals (connect external normally open reset button; shorted = automatic reset)
7. 13-14 / 23-24 / 33-34: Safety outputs (for controlling main contactors)
8. 41-42: Normally closed fault feedback signal
9. Model Correction & Alternative Reference

⚠️ The most frequently confused model on the market: SNA4043K-A (4043, easily mistaken for 4053)

⚠️ Important Verification Conclusion

SNA4053K-A is NOT an official standard model in Wieland catalogues, it is highly likely a transcription error:

1. Most common miswriting: SNA4043K-A (Parte n. R1.188.1810.0)

Ripristino automatico, no reset monitoring; dual-channel with short-circuit monitoring

2. Alternative similar model: SNA4063K-A

Ripristino manuale (with reset monitoring) — this is the core difference from SNA4043

Model rules:

SNA4043K-A: Ripristino automatico

SNA4063K-A: Ripristino manuale (reset button monitoring)

Both models share identical contact configuration, safety rating and dimensions; only reset logic differs.

Quick Selection Comparison Table

Azioni consigliate

1. Verify the printed model on the physical nameplate of the unit;
2. Confirm site requirements: Reset monitoring required or not

Emergency stop circuits generally require manual reset (SNA4063K-A)

Safety light curtain applications may adopt automatic reset (SNA4043K-A)

Application Scenarios of Wieland SNA Series Relè di sicurezza (SNA4043 / SNA4063)

This series achieves PL e / Cat.4 / SIL3 with dual-channel monitoring, primarily deployed for safety circuits on machine tools and automated production lines. Content is divided into supported safety signal types, industry applications, and key selection differentiation.

1. Supported Safety Input Signals (Hardware Utilization)
2. Emergency stop buttons (dual normally closed contacts)

Most common application: Machine main emergency stop and zone emergency stop circuits.

Standard requirement: Emergency stop circuits prefer SNA4063K-A (manual reset with monitoring).

2. Safety gate switches / Magnetic safety sensors

Interlock for protective doors, maintenance doors and perimeter fencing; power circuit cutout upon door opening.

3. Barriere fotoelettriche di sicurezza

Hazard zone intrusion protection for presses, conveyor lines and robot stations.

Light curtain solutions commonly use SNA4043K-A (ripristino automatico).

4. Two-hand control devices

For stamping and riveting equipment, preventing single-hand access to hazardous zones.

5. Safety mats, safety bumpers

Perimeter intrusion detection around robot cells, automatic doors and lifting platforms.

2. Major Industry & Equipment Applications

(1) Industria delle macchine utensili

Torni CNC, machining centres, smerigliatrici, punching machines, macchine piegatrici

Applicazione: Protective door interlock, emergency stop circuits, safety light curtain protection

(2) Automated Production & Attrezzature per l'imballaggio

Macchine per l'imballaggio, palletizers, linee di trasporto, attrezzature per lo smistamento, etichettatrici

Robot workstations, gantry robot safety fence interlock

(3) Gomma & Industria della plastica

Injection moulding machines, estrusori, blow moulding equipment: Safety gates, arresto di emergenza, safety light curtains

(4) Logistica & Attrezzature per magazzinaggio

Automated warehouses, ascensori, navette, linee di smistamento

Piattaforme elevatrici, dock leveller safety interlocks

(5) Nuova energia & Attrezzatura per batterie al litio

Cell assembly machines, macchine per il riempimento di elettroliti, sealing equipment, test tooling

Wieland products are widely adopted on export machinery to meet EU CE Machinery Directive requirements

(6) Lavorazione del legno & Macchine da stampa

Panel saws, macchine da taglio, printing presses, die-cutting machine safety protection

(7) General Custom Automation

Custom test fixtures and assembly machines; deployed as core safety logic unit to cut off main contactors and servo power circuits.

3. Critical Application Selection Comparison

⚠️ SNA-4053-K-A is not an official Wieland standard model. It is almost certainly a nameplate transcription error; physical unit will be one of the two above variants.

4. Limitazioni & Applicazioni non idonee
5. Cannot directly drive high-power loads; safety contacts are intended to control contactor coils, not motors directly
6. Not suitable for solenoid valves or high-frequency switching loads
7. Cannot satisfy safety requirements higher than PL e / Cat.4 (this series already reaches Cat.4 maximum rating)

Selection Guidelines for Wieland SNA / SNO Safety Relays

Based on the SNA4043 / SNA4063 platform covered above; structured criteria ready for engineering proposals and procurement checks.

Fare un passo 1: Confirm Required Safety Rating (Mandatory Priority)

Conforme all'ISO 13849-1 / IN 62061

1. PL & Categoria

PL e / Cat.4: Highest rating. For high-risk stations including robots, stamping, injection moulding, machine tools and lithium battery equipment (supported by all mainstream SNA variants)

PL d / Cat.3: Low-risk general automation and conveyor lines

2. SIL Level

SIL 3 corresponds to PL e; preferred for machinery exported to EU

✅ Selection Rule: Do NOT downgrade safety rating for high-risk equipment.

Fare un passo 2: Determine Safety Input Channel Configuration (Dual Channel Is Standard)

Modalità canale

Dual-channel monitoring with cross short-circuit detection: Industry standard, fitted across all SNA variants. Compatible with dual normally closed safety devices (E-stop, cancelli di sicurezza, barriere fotoelettriche)

Single channel: Only permitted for low-risk scenarios; available on selected SNO variants. NOT allowed for high-risk machinery.

Compatible Sensor Types

Emergency stop switches, mechanical safety gates: Dual normally closed (NC)

Interruttori magnetici di sicurezza, safety light curtains: Dual NC / OSSD signals

⚠️ Two types of safety light curtains:

① OSSD solid-state output → Requires relay model supporting OSSD input

② Light curtain with relay converted contact output → Compatible with standard SNA4043 / SNA4063

Fare un passo 3: Modalità di ripristino (Most Common Source of Wrong Selection!)

Distinzione chiave:

Monitored reset detects open or short circuits on reset wiring and triggers safety lockout for superior safety. Simple unmonitored manual reset should be avoided on new projects.

Fare un passo 4: Tensione di alimentazione

Main Wieland options:

Suffix A = AC/DC 24 V (Automation standard, selected in 90% of projects)

Less common: 110 VCA, 230 VAC — only for legacy retrofits

Esempio: SNA4063K-A → A = AC/DC 24 fornitura V

Fare un passo 5: Tipo di terminale (Identified by Suffix K / C)

K = Pluggable screw terminals

Vantaggi: Vibration resistant, ideal for permanent cabinet installation and on-site maintenance (the unit in your photo uses K terminals)

C = Push-in spring terminals

Vantaggi: Fast wiring without screwdrivers; use cautiously under heavy vibration

Esempio: SNA4063K-A

Fare un passo 6: Output Contact Configuration

Main Safety Outputs (For Power Circuit Cutoff)

SNA4043 / SNA4063: 3 normally open safety contacts

Scopo: Wired in series with main contactor coils for redundant shutdown

Auxiliary Signal Contacts (PLC Feedback)

1 built-in normally closed fault contact

Opens upon safety activation or relay fault; used for alarm indicators and PLC signalling

Nota sulla selezione: If multiple feedback signals are required, add auxiliary relays. Safety contacts should not be expanded externally.

Contatta i coefficienti di carico

AC-15: 230 V / 5 UN

DC-13: 24 V / 5 UN

👉 Never drive motors directly; only control contactor coils!

Fare un passo 7: Montaggio & Specifiche fisiche

1. Montaggio: Standard DIN 35 guida da mm
2. Larghezza: SNA40xx series 22.5 mm, compact design saving cabinet space
3. Valutazione ambientale: IP20 (solo per installazione in armadio; not for outdoor direct deployment)

Fare un passo 8: Differentiate SNA vs SNO Series (Frequent Confusion)

SNA Series: Dual-channel safety monitoring, up to PL e Cat.4; for emergency stop, cancelli di sicurezza, barriere fotoelettriche (your target series)

SNO Series: Predominantly single channel, lower safety rating generally PL d and below; low-cost basic solutions

Common Selection Pitfalls Checklist

1. ❌ Misapplication: Using automatic reset SNA4043 for emergency stop circuits — violates machinery safety standards, fails third-party audit & Certificazione CE
2. ❌ Transcription error SNA-4053-K-A: No official model; physical unit is either SNA4043 or SNA4063
3. ❌ Direct drive of solenoid valves or high-power loads with safety contacts → contact burnout and loss of safety function
4. ❌ Mixing K screw terminals and C spring terminals, leading to mismatch on delivery
5. ❌ Ignoring reset monitoring requirements → machine fails acceptance testing

Rapid Selection Workflow (For Field Engineers)

1. Identify safety device: Arresto di emergenza / safety gate → select SNA4063xx-A (monitored manual reset); Light curtain / safety bumper → SNA4043xx-A (ripristino automatico)
2. Confirm supply voltage: Default AC/DC24V suffix A
3. Seleziona il tipo di terminale: Permanent cabinet installation → K screw terminal; high volume assembly for fast wiring → C spring terminal
4. Verify safety rating: High-risk equipment requires PL e / Cat.4 / SIL3
5. Confirm number of safety contacts sufficient for contactor control

Complete Official Model List of Wieland SNA40xx Safety Relays

Series Profile: safeRELAY SNA40xx dual-channel safety monitoring, PL e / Cat.4 / SIL3, Montaggio su guida DIN;

⚠️ Important Notice: SNA-4053-K-A is NOT an official Wieland model, it is a transcription error. Official core variants are limited to 4043 / 4044 / 4063 / 4064;

Industry standard: Suffix A = AC/DC24 V (automation default). Specify A suffix for new orders.

1. Regole di denominazione dei modelli

`SNA 40XX [terminale][Reset]-[Voltage Suffix]`

1. SNA: Dual-channel safety monitoring base unit
2. 40XX:

4043: 3 safety NO contacts, ripristino automatico (no reset monitoring)

4044: 4 safety NO contacts, ripristino automatico (no reset monitoring)

4063: 3 safety NO contacts, ripristino manuale (with reset circuit monitoring)

4064: 4 safety NO contacts, ripristino manuale (with reset circuit monitoring)

Ultima cifra 3 = 3 safety NO contacts; Ultima cifra 4 = 4 safety NO contacts

3. Terminal Code

K: Pluggable screw terminals (most widely used in projects)

C: Pluggable Push-in spring terminals

4. Extended Reset Suffix (KM/KE)

KM: Simple manual reset without monitoring; rarely specified for new projects

5. Voltage Suffix

UN: CA/CC 24 V (automation standard)

Nessun suffisso: Fixed screw terminals (legacy models, gradualmente eliminato)

2. Mainstream Models for Domestic Projects (24 V CA/CC)

SNA4043 Series | Ripristino automatico, 3 Safety NO Contacts

SNA4044 Series | Ripristino automatico, 4 Safety NO Contacts

SNA4063 Series | Ripristino manuale (Monitored), 3 Safety NO Contacts【Preferred for Complete Machinery】

SNA4064 Series | Ripristino manuale (Monitored), 4 Safety NO Contacts

3. Legacy Non-Standard Voltage Models (Only For Equipment Replacement, Not Recommended For New Projects)

Fixed non-pluggable screw terminals (no suffix A)

SNA4043K: AC42~48 V / AC115 V / AC230 V

SNA4063K: AC230 V

Nota: All new domestic machinery shall adopt AC/DC24 V models with suffix -A

4. General Specifications Applicable to All Variants
5. Valutazione di sicurezza: PL e / Cat.4, SIL 3 (EN ISO13849-1, EN62061)
6. Contact Ratings: AC-15 230 V/5 A; DC-13 24 V/5 A
7. Montaggio: DA 35 guida da mm; Larghezza 22.5 mm; IP20 (Cabinet installation only)
8. Caratteristiche: Dual-channel cross short-circuit monitoring, EDM external device monitoring support, 3 status LED indicators
9. Cablaggio: Supports single-channel / dual-channel connection modes
10. Quick Selection Summary Table

6. Procurement Reminders
7. If customer submits model `SNA-4053-K-A` → Confirm transcription error immediately. Check physical nameplate; the actual unit is almost certainly SNA4063K-A.
8. Always include complete model + manufacturer part number in BOM to avoid delivery mismatch between K screw terminals and C spring terminals.
9. Do not interchange automatic reset SNA4043 and monitored manual reset SNA4063; incorrect selection will lead to failed safety acceptance.
10. Contact count selection: 3 contactors or less → SNA4063; ≥4 contactors requiring synchronous shutdown → select SNA4064.