Forcibly guided coupling relay - PSR-PS21-1NO-1NC-24DC-SC 2700357

Coupling relay for SIL 2 high- and low-demand applications, couples digital output signals to the I/O, 1 enabling current path, 1 confirmation current path, 1 digital signal output, safe state off applications, test pulse filter, fixed screw terminal block

Product Details

Ambient conditions
Shock 15g
Min. degree of protection of inst. location IP54
Vibration (operation) 10 Hz ... 150 Hz, 2g
Maximum altitude ≤ 2000 m (Above sea level)
Ambient temperature (operation) -40 °C ... 65 °C (observe derating)
Max. permissible relative humidity (operation) 75 % (on average, 85% infrequently, non-condensing)
Ambient temperature (storage/transport) -40 °C ... 85 °C
Degree of protection IP20
Max. permissible humidity (storage/transport) 75 % (on average, 85% infrequently, non-condensing)

Signal: M1
Short-circuit protection no
Maximum inrush current 500 mA (Δt = 1 ms at Us)
Number of outputs 1 (non-safety-related)
Voltage approx. 22 V DC (UD - 2 V)
Output fuse 150 mA fast blow
Output description PNP
Current max. 100 mA
Relay: Confirmation current path
Contact material AgCuNi, + Au
Switching frequency max. 1 Hz
Contact type 1 confirmation current path
Number of outputs 1 (safety-related N/C contacts: 21/22)
Output fuse 150 mA Fast-blow
Limiting continuous current 100 mA
Output description 1 N/C contact, without delay, not floating (reference ground: A2)
Switching voltage min. 20.4 V DC
max. 26.4 V DC
Mechanical service life 10x 106 cycles
Inrush current min. 1 mA
max. 100 mA
Switching capacity min. 20 mW
Relay: Enabling current path
Contact material AgSnO2
Contact type 1 enabling current path
Output fuse 6 A gL/gG
4 A gL/gG (for low-demand applications)
Limiting continuous current 6 A (High demand)
4 A (Low demand)
Sq. Total current 36 A2 (observe derating)
Mechanical service life 10x 106 cycles
Switching frequency max. 1 Hz
Number of outputs 1 (safety-related N/O contacts: 13/14)
Switching capacity according to IEC 60947-5-1 4 A (24 V (DC13))
5 A (250 V (AC15))
Output description 1 N/O contact, without delay, floating
Switching voltage min. 12 V AC/DC
max. 250 V AC/DC (Observe the load curve)
Inrush current min. 3 mA
max. 6 A
Switching capacity min. 60 mW

Utilization restriction
EMC note EMC: class A product, see manufacturer's declaration in the download area
CCCex note Use in potentially explosive areas is not permitted in China.

Rated insulation voltage 250 V AC
Nominal operating mode 100% operating factor
Maximum power dissipation for nominal condition 2.35 W (IL2 = 36 A2)
Rated surge voltage/insulation Safe isolation, 6 kV reinforced insulation from control circuit, start circuit, confirmation current path, signal output to the enabling current path; 4 kV/basic insulation between all current paths and housing
Rated control circuit supply voltage US 20.4 V DC ... 26.4 V DC
24 V DC -15 % / +10 % (A1/A2)
Inrush current at UD typ. 2.5 A (Δt < 20 µs at UD)
Diagnostic supply voltage UD 24 V DC -15 % / +10 % (21/A2)
Filter time max. 2 ms (at A1-A2; test pulse width)
≥ 100 ms (at A1-A2; test pulse rate)
Input current at UD 6 mA (at 21-A2 for UD; depending on load + 100 mA at M1 and 22)
Power consumption at US typ. 1.08 W
Protective circuit Serial protection against polarity reversal; Suppressor diode 33 V (A1/A2), 38 V (21/A2)
Inrush current typ. 400 mA (Δt < 10 µs at Us)
Rated control supply current IS typ. 45 mA

Height 93.1 mm
Width 6.8 mm
Depth 102.5 mm

Indication 1 x red LED
Status display 2 x green LEDs
Operating voltage display 1 x yellow LED

Housing color yellow
Housing material PBT

Mounting position vertical, horizontal, with front of module upward
Assembly instructions See derating curve
Mounting type DIN rail mounting

Safety data: IEC 61508 - High demand
Duration of use 240 Months
Proof test interval 240 Months
λSD 494.66 FIT
Safety Integrity Level (SIL) 2
Designation For use in high-demand applications, the diagnostics function must be implemented via the confirmation current path.
Probability of a hazardous failure per hour (PFHD) 8.8 x 10-9 (4 A DC13; 5 A AC15; 8760 switching cycles/year)
Equipment type Type A
λSU 79.10 FIT
λDU 8.80 FIT
Safe Failure Fraction (SFF) 99.18 %
λDD 494.66 FIT
MTBF 91.65 Years
Safety data
Stop category 0
Safety data: EN 50156
Safety Integrity Level (SIL) 2
Safety data: IEC 61508 - Low demand
Duration of use 240 Months
Proof test interval 20 Months
Probability of a hazardous failure on demand (PFDAVG) 1.34 x 10-3
8.06 x 10-4 (for proof test interval = 1 year)
Safety Integrity Level (SIL) 2
Equipment type Type A
λSU 794.1 FIT
λDU 183.8 FIT
Safe Failure Fraction (SFF) 81.2 %
MTBF 99 Years

UL certificate E140324
IECEx certificate IECEx ULD 14.0003X
Environmental simulation test ISA-S71.04 (G3)
EU-type examination certificate DEMKO 14 ATEX 1284X
ATEX  II 3 G Ex nA nC IIC T4 Gc
Conformance CE-compliant
Certificate of classification 11253-14 HH
UL, USA/Canada cULus
Class I, Zone 2, AEx nA nC IIC T4 / Ex nA nC IIC Gc T4 X
Class I, Div. 2, Groups A, B, C, D, T4
IECEx Ex nA nC IIC T4 Gc

Connection technology
pluggable no
Conductor connection
Torque 0.5 Nm ... 0.6 Nm
Conductor cross-section AWG 24 ... 12
Screw thread M3
Conductor cross section solid 0.2 mm2 ... 2.5 mm2
Stripping length 12 mm
Connection method Screw connection
Conductor cross section flexible 0.2 mm2 ... 2.5 mm2

Air clearances and creepage distances between the power circuits
Standards/regulations DIN EN 50178, EN 60079-15

Relay type Electromechanical relay with force-guided contacts in accordance with IEC/EN 61810-3
Application Safe switch off
High demand
Low demand
Typical release time < 35 ms (when controlled via A1)
Recovery time 500 ms
Typ. starting time with Us < 100 ms (with Us when controlled via A1)
Insulation characteristics
Overvoltage category III

Order Key 2700357
Packing unit 1 pc
Minimum order quantity 1 pc
Sales Key CNA
Catalog Page Page 249 (C-6-2019)
GTIN 4046356912907
Weight per Piece (including packing) 160,0 GRM
Weight per Piece (excluding packing) 63,6 GRM
Customs tariff number 85364900
Country of origin DE

UL Listed

cUL Listed

UL Listed

cUL Listed

Functional Safety




Functional Safety

cULus Listed


UL Listed

cUL Listed


REACh SVHC Lead 7439-92-1
China RoHS Environmentally Friendly Use Period = 50 years
China RoHS For details about hazardous substances go to tab “Downloads”, Category “Manufacturer's declaration”

Compatible Products

Your advantages

Low housing width of just 6.8 mm
Corrosion protection due to conformal coating of the PCB
Up to SIL 2 according to IEC 61508
Forcibly guided contacts according to EN 50205
Easy proof test according to IEC 61508 thanks to integrated signal contact
Approved for Class I, Zone 2 applications
1 enabling current path, 1 digital signal output, 1 diagnostic current path
Couples digital output signals from failsafe controllers to I/O devices (valves, etc.) for electrical isolation and power adaptation
Long service life thanks to filtering of controller test pulses