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

Applied standardsEN ISO 13849-1; EN 62061;
EN 60204-1, BG-GS-ET-20;
EN 60947-5-1, -3; EN 61326-3-1
Enclosureblack polycarbonate
Contact materialSilver, gold flashed
MountingDIN rail mounting
Connectionscrew connection 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
Tightening torquescrew connection terminals: approx. 0.8 Nm
Degree of protectionenclosure IP 40, terminal block IP 20 to IEC/EN 60529, protection against contact to VBG 4
Safety-relevant data:
EN 62061SIL CL 3
PFHd3 x 10-8 1/h
EN ISO 13849-1Performance Level PL e
TMmax. 20 years
MTTFd> 113 years
DC/DCavg> 99 %
hop8 h/day
dop220 days/year
tzyklus30 s
EN 60204-1stop category 0
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
Rated operating current/voltage Ie/Ueto EN 60947-5-1: 2 A/230 VAC; 1 A/24 VDC
to CSA: B300/R300, 250 VAC
Conventional thermal current Ithe5 A
Utilisation categoryAC-15; DC-13
Contact load capacitymin. 10 mA
Typ. input current22 mA
Typ. input voltage20 VDC
Max. load of signalling output Y120 mA
Short-circuit protectionpower 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
Overvoltage categoryIII
Ambient temperature–22 °C … +55 °C
Storage and shipping temperature–22 °C … +70 °C
Relative humidity10 % ... 90 %
Shock resistance15 g
NoteInductive loads (contactors, relays etc.) are to be suppressed by suitable circuitry.
The safety-related data are based on a load of 24 V / 1 A / DC-1 for the enabling paths. With higher load currents for the enabling paths and other requirement rates nop, the safety-related data vary from the given data and can be provided on request.
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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