ELESTA SIR222P Forcibly Guided Safety Relay

ELESTA (Swiss safety relay brand under Pilz) SIR4 Power high-current PCB-mount safety relay

1. SIR: SIR4 series safety relay with forcibly guided contacts
2. 222: Contact configuration: 2 Normally Open (NO) + 2 Normally Closed (NC) (dual-pole double-throw safety structure)
3. P: High-current version rated for 12A load (standard SIR222 is 10A)

Standard stock coil specifications:

SIR222P 24VDC (mainstream, part number H301164, coil resistance 760Ω)

SIR222P 12VDC (part number H301192)

Custom coil voltages available: 5/6/18/48/110VDC

Core Safety Certifications

Compliant with IEC 61810-3 Type A Forcibly Guided Contacts and EN50205 machinery safety standards. Applicable to machine tool and automated safety circuits to meet safety contact fault monitoring requirements.

2. Mechanical Dimensions & Mounting

Overall size: 46.4(L) × 16(W) × 30.7(H) mm

Mounting: Through-hole PCB soldering (14-pin footprint)

Weight: Approx. 32g

Housing: Transparent green dustproof flame-retardant PC, allows visual inspection of coil and contact status

Standard through-hole pin pitch for PCB mounting; compatible with dedicated PCB sockets

3. Coil Electrical Parameters (DC)

4. Core Contact Electrical Ratings (2NO+2NC Safety Forced Linkage)

4.1 Load Capacity (High-Current Advantage of SIR222P)

Continuous rated current: 12A / 250VAC (AC1 resistive load)

Peak inrush current: Max. 60A (20ms, suitable for inductive startup of motors and contactors)

Switching voltage range: AC 5~480V / DC 5~250V

Rated switching capacity: 3000VA

Minimum reliable switching load: 5mA / 5V (no sticking for weak signal circuits)

Contact material: AgSnO2 silver tin oxide, arc-resistant and anti-welding

4.2 Core Feature of Forcibly Guided Safety Design (Distinction from Standard Relays)

Forced mechanical linkage: NO and NC contacts within the same channel can never conduct simultaneously

Monitoring logic: Safety circuits can detect NC feedback signals to judge contact welding faults

Dielectric withstand voltage between contacts: 4000VAC; open contact withstand voltage: 1500VAC

Contact creepage distance: ≥10mm between coil and output contacts; ≥8mm between two output contact banks for enhanced isolation protection

4.3 Service Life Ratings

Mechanical life: 10 million operations under no-load conditions

Electrical life (12A/250VAC resistive): 250,000 operations

Factory contact resistance: ≤100mΩ (tested at 6V/100mA)

5. 14-Pin Pinout Definition (Standard Top Silkscreen Layout)

Coil Pins (Drive Side)

13(+), 14(-): DC coil positive and negative terminals with built-in diode. Connect 14 to 0V and 13 to DC24V.

Two Independent Safety Contact Banks (1NO+1NC per bank with forced linkage)

Channel 1 (First Contact Bank)

1: Common COM1 | 2: NC Normally Closed | 3: NO Normally Open

Channel 2 (Second Contact Bank)

4: Common COM2 | 5: NC Normally Closed | 6: NO Normally Open

Pins 7~12 are unoccupied locating pins with no electrical connections.

6. Environmental Operating Parameters

Operating temperature: -40℃ ~ +70℃

Storage temperature: -40℃ ~ +85℃

Humidity: 5%~95% RH non-condensing

Vibration / Shock resistance: IEC60068 industrial equipment grade, suitable for machine tool and production line control cabinets

7. Typical Application Scenarios (Dedicated for Safety Circuits)
8. Dual-channel monitoring for machine safety door and emergency stop circuits (NC contacts detect welding faults)
9. Safe cut-off circuits for inverter and servo enable signals
10. Output expansion for safety light curtains and safety mats on automated production lines
11. Safety control circuits for rail transit, medical equipment and lifts
12. High-current output expansion for PLCs (direct drive of contactors and solenoid valves up to 12A)
13. Equipment fault diagnosis feedback (self-inspection of contact adhesion via NC contacts)
14. Cross-Series Model Selection Comparison Table

9. Troubleshooting Matrix

10. Mandatory Installation & Usage Prohibitions
11. NC contact safety monitoring must not be omitted: Safety devices must read NC feedback signals; otherwise anti-welding protection is lost.
12. Long-term resistive load shall not exceed 12A; inductive loads are recommended to be derated to 8A.
13. DC coils must not be energized with reversed polarity for extended periods (built-in diode only provides one-time transient protection; sustained reverse voltage burns the coil).
14. Prohibit full-load continuous operation above 70℃ in sealed cabinets; sufficient heat dissipation space must be reserved.
15. Do not parallel contacts of different relays for current expansion; single-channel load cannot exceed rated current of one contact.
16. Only PCB soldering mounting is allowed; avoid violent bending or repeated plugging/unplugging of pins.
17. Standard Packing List

1 × SIR222P relay unit

2. Original manufacturer safety datasheet, TÜV/CE safety certification documents
3. Standard package quantity: 15 pieces per box

Application Manual for ELESTA SIR222P Forcibly Guided Safety Relay

Document Version: V1.0｜Applicable Models: SIR222P-24VDC (mainstream), SIR222P-12VDC

Brand: ELESTA (Switzerland)｜Safety Standards: IEC 61810-3 Type A Forcibly Guided Contacts, EN50205, ISO13849-compliant safety circuit design

Table of Contents

1. Product Overview & Model Code Explanation
2. Complete Electrical Specifications
3. Pinout Definition & Standard Wiring Specifications
4. 4 Standard Industrial Wiring Schemes (Including Safety Circuits)
5. PCB Mounting, Soldering & Mechanical Installation Standards
6. Load Selection & Derating Guidelines
7. Core Rules for Safety Circuit Design (Requirements for Forcibly Guided Contacts)
8. Power-On Commissioning & Functional Test Procedures
9. Troubleshooting Matrix
10. Mandatory Installation & Usage Prohibitions
11. Cross-Series Alternative Model Comparison
12. Packaging & Certification Documents
13. Product Overview & Model Code Explanation

1.1 Model Code SIR222P

SIR: SIR4 Power series PCB-mounted forcibly guided safety relay

222: Contact structure: 2NO + 2NC, two independent banks of 1NO+1NC forced-linkage contacts

P: High-current version with 12A AC1 continuous rating per contact (standard SIR222 is only 10A)

1.2 Core Safety Features (Distinction from Ordinary Relays)

1. Forcibly Guided Mechanical Structure: NO and NC contacts within one channel can never conduct simultaneously. If contacts weld shut, the paired opposite contacts remain open to enable fault diagnosis.
2. Coil-to-contact dielectric withstand voltage: 2500VAC; inter-contact isolation: 4000VAC. Creepage distances meet safety isolation criteria.
3. AgSnO2 silver tin oxide contacts with thin gold plating, anti-arcing and anti-welding, compatible with both high-current loads and weak signal detection.
4. Built-in coil freewheeling diode (dedicated for DC coils to prevent reverse voltage breakdown).

1.3 Applicable Safety Performance Levels

Suitable for PLd / Cat.3, SIL2 safety cut-off circuits. Dual-channel redundant design achieves Cat.4 / PLe.

2. Complete Electrical Specifications

2.1 Coil Parameters (DC)

2.2 Contact Load Ratings (Per 1NO/1NC Channel)

1. AC1 resistive: 12A / 250VAC, max switching capacity 3000VA
2. AC15 inductive (contactors / solenoid valves): 8A / 250VAC (derating mandatory)
3. DC13 inductive: 5A / 24VDC
4. Peak surge current: 60A (short-duration 20ms)
5. Minimum reliable switching load: 5mA / 5V (no poor contact for PLC weak feedback signals)
6. Contact material: AgSnO2 with 0.2~0.4μm gold plating
7. Factory contact resistance: ≤100mΩ (6V/100mA test condition)

2.3 Service Life Ratings

Mechanical life (no load): 10 million operations

Electrical life (12A/250VAC resistive): 250,000 operations

Electrical life (8A inductive load): 100,000 operations

2.4 Environmental & Mechanical Parameters

Overall dimensions: 46.4(L)×16(W)×30.7(H)mm, 14-pin through-hole PCB mount

Weight: 32g

Operating temperature: -40℃ ~ +70℃ (enhanced heat dissipation required for full load at 70℃)

Storage temperature: -40℃ ~ +85℃

Humidity: 5%~95% RH non-condensing

Vibration resistance: 10~55Hz, 1.5mm amplitude for 2 hours on each of three axes

Housing: Transparent green flame-retardant PC for visual contact inspection

3. Pinout Definition (Top Silkscreen View, Standard PCB Footprint)

3.1 Coil Drive Pins

13: Coil positive DC+

14: Coil negative DC(cathode of built-in diode; sustained reverse connection prohibited)

3.2 Two Independent Forcibly Guided Contact Banks (COM+NC+NO per bank)

Channel 1 (First Safety Contact Bank)

1: Common COM1

2: NC1 Normally Closed (forced linkage feedback contact)

3: NO1 Normally Open (main power output)

Channel 2 (Second Safety Contact Bank)

4: Common COM2

5: NC2 Normally Closed (forced linkage feedback contact)

6: NO2 Normally Open (main power output)

3.3 Unoccupied Pins

Pins 7,8,9,10,11,12: Locating reinforcement only, no electrical connection, wiring forbidden.

3.4 Forced Linkage Logic (Core Safety Principle)

Coil de-energized (open state): Pins 2-NC1 and 5-NC2 conduct; Pins 3-NO1 and 6-NO2 open

Coil energized (pulled-in state): Pins 2-NC1 and 5-NC2 open; Pins 3-NO1 and 6-NO2 conduct

Fault judgment rule: If NC contacts remain closed after coil energization → NO contacts welded shut; safety circuit triggers fault and equipment shutdown.

4. Four Standard Industrial Wiring Schemes

Scheme 1: Dual-Channel Safety Cut-Off Circuit (Emergency Stop / Safety Door, Most Common)

Function Description

Two independent NO contacts cut servo/inverter enable signals; two NC contacts connect to PLC for contact welding fault monitoring, complying with ISO13849 Cat.3 safety requirements.

Wiring Steps

1. Coil drive: PLC 24V+ output → Pin13; 0V → Pin14
2. Power output circuit (two independent cut-off paths, parallel connection prohibited)

Channel 1: 24VAC/DC supply → COM1(Pin1); NO1(Pin3) → Servo Enable Coil 1

Channel 2: 24VAC/DC supply → COM2(Pin4); NO2(Pin6) → Servo Enable Coil 2

3. Fault feedback monitoring (NC contacts wired to PLC digital input)

NC1(Pin2) and NC2(Pin5) shorted together and connected to PLC PNP input; PLC logic: NC contacts must open when relay pulls in. Continuous conduction indicates contact welding and locks out equipment startup.

Mandatory Safety Rule

Two output loads must be independent. Parallel connection of NO1 and NO2 for current expansion destroys dual-channel redundant safety design.

Scheme 2: PLC High-Current Output Expansion (Solenoid Valve / Contactor Drive)

Application Scope

PLC single-point output current ≤0.5A, insufficient for direct drive of 10A solenoid valves; SIR222P expands contact current capacity.

1. Coil: PLC output drives Pins13/14 (24VDC)
2. Main circuit AC220V live wire → COM1(Pin1), COM2(Pin4)
3. NO1(Pin3) and NO2(Pin6) parallel to solenoid coil (parallel allowed for resistive loads, not recommended for inductive loads)
4. NC contacts unused or wired to alarm indicator light (light illuminates when relay de-energized)

Scheme 3: Equipment Self-Diagnosis Circuit (Safety Light Curtain Output Expansion)

1. Dual-channel NC signals from safety light curtain wired in series to drive relay coil Pins13/14
2. Two NO contacts cut main contactor power supply; two NC contacts feed real-time contact status to PLC
3. Logic: Curtain blocked → coil de-energized → NO contacts open and machine stops; If NC contacts stay closed with unobstructed curtain, relay contact damage is detected and alarm interlock activates.

Scheme 4: Mixed Weak Signal & High-Current Circuit (Contact Channel Isolation)

1. Channel1 NO contacts: Drive high-current AC220V contactors
2. Channel2 NC contacts: Feed 5V weak feedback signal to MCU IO ports (gold-plated contacts guarantee stable low-current contact performance)

Prohibition: Do not share one contact bank for both high-current inductive loads and 5V weak signals; arcing contaminates contact surfaces and causes intermittent weak signal faults.

5. PCB Mounting & Soldering Standards

5.1 PCB Pad Design Requirements

Pin hole diameter: 1.3mm, pad diameter ≥2.2mm

Standard pin pitch layout compatible with all 14-pin relays

Wider copper traces for COM/NO/NC high-current pins; copper thickness ≥35μm, trace width ≥5mm for 12A loads

5.2 Soldering Process Specifications

1. Wave soldering peak temperature ≤260℃, contact duration ≤4s; hand iron temperature ≤350℃, single pin soldering time ≤3s
2. Prolonged high-temperature heating of pins is forbidden, as it melts internal contact plastic supports
3. Solder joints must be fully filled without cold solder or bridging between adjacent pins
4. Clean flux residue after soldering to prevent leakage and creepage currents

5.3 Heat Dissipation Requirements

Continuous full 12A operation: Increase PCB copper trace heat dissipation area; cabinet ambient temperature ≤60℃

Ambient temperature of 70℃: Load must be derated to ≤8A

6. Load Selection & Derating Standards

Recommended Arc Suppression Measures

Fit absorption components across inductive load coils:

AC loads: RC absorption circuit (0.1μF capacitor in series with 100Ω resistor)

DC loads: Freewheeling diode wired in reverse parallel across coil terminals

7. Mandatory Core Rules for Safety Circuit Design (Violation Invalidates Safety Certifications)
8. NC contact monitoring cannot be omitted

All safety cut-off circuits (emergency stop, safety doors, light curtains) must route both NC contact banks to the upper controller (PLC) for welding diagnosis. Circuits without monitoring fail to meet IEC61810-3 safety requirements.

2. Dual-channel outputs must not be paralleled

Two NO contacts provide redundant safety cut-off; each must drive an independent load. Parallel connection eliminates fault isolation capability.

3. Single-channel cut-off is prohibited for safety applications

Using only one NO contact to cut power while leaving the other unused downgrades safety classification directly to Cat.1 and fails machine safety acceptance tests.

4. Do not series multiple safety relay contacts for current expansion

Multi-stage series connection increases contact failure probability and reduces safety level.

5. Coil power supply must share the same source as the safety circuit. Separate power supplies cause asynchronous logic operation.
6. Power-On Commissioning & Functional Test Procedures

8.1 Static Pre-Power Test (Multimeter Required)

1. Coil de-energized state: Measure continuity between 1-2 and 4-5; open circuit between 1-3 and 4-6
2. Measure coil resistance at Pins13/14 (760Ω for 24VDC model) to rule out short/open circuits
3. Verify no continuity between unoccupied pins and coil/contact terminals

8.2 Energized Pull-In Test

1. Apply rated DC24V to Pin13(+) and Pin14(-)
2. Multimeter verification: Open circuit between 1-2 and 4-5; continuity between 1-3 and 4-6
3. Cut coil supply voltage; contacts reset rapidly to original state

8.3 Safety Fault Simulation Test (Mandatory for Acceptance)

Manually simulate NO contact welding by shorting Pins1 and 3. With coil energized, NC1 (Pin2) remains conductive. PLC detects persistent NC closure and triggers fault alarm to validate the forcibly guided mechanical design.

9. Troubleshooting Matrix

10. Absolute Installation & Usage Prohibitions
11. Omission of NC contact welding monitoring on safety cut-off circuits voids safety certification validity.
12. Continuous resistive loads exceeding 12A or inductive loads exceeding 8A burn contact sets.
13. Long-term reverse energization of DC coils destroys the built-in freewheeling diode.
14. Do not run continuous full 12A loads above 70℃ in sealed cabinets.
15. Do not share one contact bank for both high-current inductive loads and 5V weak signal circuits.
16. Parallel connection of two NO contacts for current expansion is forbidden in safety circuit applications.
17. Prolonged full-load operation at ambient temperature above 70℃ is prohibited.
18. Violent pin bending, repeated plugging/unplugging, and extended high-temperature soldering are forbidden.
19. Do not deploy in circuits above AC480V, exceeding contact voltage withstand ratings.
20. Cross-Series Alternative Selection Comparison

12. Packaging & Certification Documents

12.1 Standard Packing List

1 × SIR222P-24VDC safety relay

2. Original manufacturer datasheet
3. Copies of CE and TÜV safety certification
4. Standard carton quantity: 15 pieces per box

12.2 Compliance Certifications

CE Industrial Equipment Certification

TÜV IEC 61810-3 Type A Forcibly Guided Contact Certification

EN50205 Machinery Safety Standard Compliance

RoHS Lead-Free Environmental Compliance Certification