Description of the individual safety relays
3.6 3TK28 safety relays with relay enabling circuits
3TK28 safety relays
82 Manual, 07/2016, NEB926157502000/RS-AB/003
3TK2827 / 3TK2828 safety relays
3.6.7.1
Applications
Applications of the 3TK2827/28 safety relay
You can use 3TK2827/28 safety relays in:
● EMERGENCY STOP devices acc. to DIN EN / IEC 60947-5-5
● Safety circuits acc. to DIN EN / IEC 60204-1, e.g. for monitoring safety guards
● Circuits in which controlled shutdown, STOP category 1 is necessary.
Depending on the external circuitry, you can achieve maximum performance level
PL
e
/Cat. 4/SIL 3 for instantaneous enabling circuits and maximum performance level
PL
d
/Cat. 3/SILCL 2 acc. to DIN EN ISO 13849-1/IEC 62061 for time-delayed enabling
circuits with this device.
Description of function and connection information
The 3TK2827/28 safety relays have two time-delayed and two instantaneous enabling
circuits as NO circuits and one instantaneous signaling circuit as an NC circuit. The
operating state and functioning are indicated by five LEDs.
When the EMERGENCY STOP buttons or the limit switch are released, when the ON circuit
Y33, Y34 is closed, the redundant safety relay, the electronics, and the controlled motor
contactors are checked for correct functioning.
With the 3TK2827 (monitored start), the ON circuit Y33, Y34 is checked for a short-circuit,
that is, it is identified as a fault if Y33, Y34 is closed before the EMERGENCY STOP button
is closed.
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