Siemens 3TK28 - Display of the Operating State

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
85
3.6.7.5
Display of the operating state
The operating state and functioning of the device are indicated by five LEDs:
● POWER
● CHANNEL 1
● CHANNEL 2
● CH 1 (t)
● CH 2 (t)
Operating states of 3TK2827/28
= off
= on
LED
Operation
POWER Ch 1 Ch 2 Ch 1 (t) Ch 2 (t) Line
supply
EMERGENCY
STOP
ON Enabling circuit
On Not pressed Pressed Closed
Pressed, delay
time running
Not pressed FK1 & FK2 open,
FK1 (t) & FK2 (t)
closed
Pressed
Not pressed
Open
Not pressed
Not pressed
Open
Fault
• Relay welded
• Motor contactor welded
• Fault in electronics
• Short-circuit in ON circuit
Open
Cross-circuit in EMERGENCY STOP circuit (minimum fault
current I
Kmin
= 0.5 A;
PTC fuse responds) or supply voltage missing
Ch1 = Channel 1
Ch2 = Channel 2
FK1 = enabling circuit 1, instantaneous
FK2 = enabling circuit 2, instantaneous
FK1 (t) = enabling circuit 1, time-delayed
FK2 (t) = enabling circuit 2, time-delayed