Safety relay - Two-hand control relay SNZ 4052K
  • Safety relay - Two-hand control relay SNZ 4052K

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Safety relay - Two-hand control relay SNZ 4052K

•  Stop Category 0 according to EN 60204-1
• Two-channel actuation; 1 NO contact and
1 NC contact for each channel
• Cross monitoring
• Monitoring of synchronous activation
• 2 enabling current paths, 1 signaling current pathy 


• Protection of people and machinery
• Monitoring of two-hand applications
• Monitoring of safety gates
• According to EN 574 Type IIIC
• Up to PL e / Category 4 (EN ISO 13849-1)
• Up to SIL CL 3 (EN 62061)


The device complies with EN 574 Type III C safety requirements. The safety behavior of the device is designed for applications according to Category 4 (EN 954-1). The device is single-fault safe and self-monitoring. Synchronous activation of both actuators (two-hand momentary contact or safety gate contacts) is monitored. Each of the two actuators is connected to the device with an NO contact and an NC contact. The technical design of the input circuit provides cross connection and ground fault monitoring. The output function is designed with 2 NO contacts as an enabling current path and 1 NC contact as signaling current path (all forcibly guided). With supply voltage applied to terminals A1/A2 and the feedback loop (terminals Y1/Y2) closed, the enabling current paths are closed by simultaneously activating the actuators (S1+S2). Both actuators must be activated within 0.5 s for the output contacts to be enabled. If only one of the two actuators is released, thedevice is immediately de-energized. The enabling current paths open. The device can be restarted only after both actuators have returned to their initial position (for example when the two-hand momentary contact switches have been released) and the feedback circuit is closed again. The feedback circuit should only be opened again after both actuators are activated. Otherwise the device will remain in the OFF position. The current status of the device is indicated by 3 LEDs: application of the supply voltage with LED SUPPLY, activation of both actuators with LED K1 and additionally with LED K2 in case of synchronous activation

Proper use
Machines whose operation requires repeated motion of the hands into the hazardous zone may be operated with this device.
• The safety category according to EN 954-1 depends on the external circuitry, the choice of control devices and their placement on the machine.
• SNE expansion devices or external contactors with positively driven contacts can be used to multiply the enabling current paths.
• The device and the contacts must be protected with max. 6 A utilization category gG or through circuit breakers with trigger characteristic B or C.
• The devices must be installed in a control cabinet with a protection degree of at least IP 54.

Please also note the information provided by your trade association.

Connection scheme


SNZ 4052K/K-A AC/DC 24 V
SNZ 4052K/K-A AC 115 – 120 V/AC 230 V


Function diagram


A1/ A2 supply voltage, LED SUPPLY
Actuator S1
Actuator S2
K1, LED K1
K2, LED K2
Synchronous monitoring
13/14, 23/24
tE = response time
tA = release time
tW = recovery time
tS = synchronous monitoring time
(1) Enabled in case of synchronous activation.
(2) Enabled in case of synchronous activation. If one of the actuators is released,
the unit will be immediately disabled. It can be enabled again only after both actuators
have been released.

(3) Not enabled in case of asynchronous activation

SNE 4004K/KV SNE 4004K-A/KV-A
type Nominal voltage Terminals      numer         pce/package.
SNZ 4052K
AC/DC 24 V           50 - 60 Hz
screw terminals R1.188.0450.1     1
AC 115 - 120 V      50 - 60 Hz
screw terminals R1.188.0920.1     1
AC 230 V               50 - 60Hz
screw terminals R1.188.0930.1     1
SNZ 4052K-A
AC/DC 24 V           50 - 60 Hz
plug screw terminals R1.188.0530.1     1
AC 115 - 120 V      50 - 60 Hz
plug screw terminals R1.188.0940.1     1
AC 230 V               50 - 60Hz
plug screw terminals R1.188.0950.1     1


Technical data SNZ 4052K
Function according to EN 574-1
Two-hand control relay
Function display
3 LEDs green
Function diagram
FD 221-9-1 W
Power supply circuit
Rated voltage Un AC/DC
24 V
Rated voltage Un AC
115 - 120 V
230 V
Rated consumption at 50 Hz i Un (AC)
3,1 VA
2,4 VA
2,4 VA
Rated consumption at 50 Hz i Un (AC)
1,9 W
2,2 W
2,2 W
Rated consumption at Un (DC)
2,4 W
Residual ripple
2,4 Vss
Electrical isolation supply circuit – control circuit
Fuse for control circuit supply
PTC thermistor
Short-circuit proof transformer
Short-circuit proof transformer
Residual ripple Uss
2,4 V
Rated frequency
50 - 60 Hz
Operating voltage range
0,85 - 1,1x UN
Control circuit
Rated output voltage (Y12 / Y14 or Y22 / Y24 and Y1), only for supply of inputs Y11, Y21 and Y2
DC 24 V
Response time  tE for K1, K2
40 ms
Release time tA
< 50 ms
Synchronous monitoring time tS
500 ms
Recovery time tW
250 ms
Output circuit