Description of the individual safety relays
3.6 3TK28 safety relays with relay enabling circuits
3TK28 safety relays
Manual, 07/2016, NEB926157502000/RS-AB/003
33
3.6.2
3TK2820 safety relay
3.6.2.1
Applications
Applications of the 3TK2820 safety relay
You can use the 3TK2820 safety relay in EMERGENCY STOP devices according to
DIN EN ISO 13850 and in safety circuits according to VDE 0113-1 or DIN EN 60204-1, e.g.
for movable guards and protective doors.
Depending on the external circuitry, SILCL 3 in accordance with IEC 62061 or PL
e
in
accordance with EN 13849-1 can be achieved. Depending on the hazard assessment,
additional measures may be necessary in the sensor circuit (e.g. protected cable
installation).
When the safety relay is used in "automatic start" mode, automatic restart (acc. to
EN 60204-1, section 9.2.5.4) after shutdown in an emergency (EMERGENCY STOP) must
be prevented by suitable means.
3.6.2.2
Description of function and connection information
The 3TK2820 safety relay has three enabling circuits (safe circuits, NO) and one signaling
circuit (non-safe, NC). The number of enabling circuits can be increased by adding one or
more 3TK2830 expansion blocks. Two LEDs indicate the operating state of the device.
The devices also monitor the sensor circuits for cross-circuits. This is done based on various
potentials in the sensor circuits.
When the EMERGENCY STOP buttons or limit switches are released and the ON button is
pressed, the internal circuit of the safety relay and the external contactors are monitored to
ensure that they are functioning correctly.
Connect the EMERGENCY STOP button or the limit switch at terminals T1/IN1 and T2/IN2.
The ON button is connected in series with the NC contacts of the external contactors
(feedback circuit) at terminals T3/IN3.
