Safety relay module SRM 21 RT2

  • Enclosure width: 22.5 mm
  • 2 NC or 1 NC/1 NO contact can be connected
  • Feedback circuit
  • 2 enabling paths
  • 1 transistor output
  • Manual or automatic reset
  • LED indicator for switching condition
  • Crossed wire monitoring

Technical data

StandardsEN ISO 13849-1,-2; EN 62061;
EN 60204-1, EN ISO 13850;
EN 60947-5-1; GS-ET 20
Enclosureblack polycarbonate; polyamide terminal clamps V0
Contact materialAgNi 10 + 0.2 µm Au
MountingDIN rail mounting
Connectionscrew terminals
with + and - screws
Cable cross-sectionmin. 1x 0.5 mm² (AWG 20)
including conductor ferrules,
max. 1x 2.5 mm² (AWG 14) including conductor ferrules,
2x 1.5 mm² (AWG 16) including conductor ferrules
Degree of protectionEnclosure IP 40, Terminal block
IP 20 to IEC/EN 60529,
shock protection to VBG 4
Safety-relevant data:*
EN 60204-1stop category 0
EN 62061SIL CL 3
PFHd3 x 10-8 1/h
EN ISO 13849-1PL e, Category 4
MTTFd> 113 years
TMmax. 20 years
DC/DCavg> 99 %
Safety requirements nop
hop8 h/day
dop220 days/year
tzyklus30 s
Rated operating voltage Ue24 VDC ±15 %
Rated operating current Ie0.125 A
Rated operating isolation voltage Ui250 VAC
Rated impulse withstand voltage Uimp4 kV
Conditional short-circuit current100 A
Inputs1 NC/1 NO contact or 2 NC contacts,
1 feedback circuit, 1 start input (monitored)
Outputs2 enabling paths, 1 transistor output as signalling output
Ie/Ue enabling paths2 A/230 VAC; 1 A/24 VDC
Utilisation categoryAC-15; DC-13
Contact load capacitymin. 10 mA
Typ. input current/
22 mA/ 20 VDC
Max. load of signalling output20 mA
Max. fuse ratingpower supply 2A slow blow, enabling paths 6 A gG/gN fuse
Delay on energisation/ deenergisation≤ 20 ms
Risk time≤ 0.5 s (switch-on delay)
Attendance delay tv< 200 ms
Mechanical life> 50 million operations
Display1 LED for supply voltage, 1 LED each for input A and B, 1 LED for authorisation
Degree of pollution2 to DIN VDE 0110
Overvoltage categoryIII
Ambient temperature–22 °C … +55 °C
Storage and shipping temperature–22 °C … +70 °C
Relative humidity10 % ... 90 %
Shock resistance3 g
NoteInductive loads (contactors, relays etc.) are to be suppressed by suitable circuitry.
Weight220 g

Ordering details

Type   Material no.  
Type    Material no.   
Safety relay module SRM 21 RT2 stock type Standard versions, in stock or available at short notice 1179203
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