Read and understand these instructions before installing, operating, or maintai-
ning the equipment.
Will cause death or serious injury.
Disconnect power before working
Reliable functioning of the equipment is only ensured with certified compon-
The devices must be installed in a switchgear cabinet with the IP32,
IP43 or IP54 degree of protection, depending on the ambient conditions.
The products described herein are designed to be components of a customized
machinery safety-oriented control system. A complete safety-oriented system
may include safety sensors, evaluators, actuators and signaling components. It
is the responsibility of each company to conduct its own evalution of the effec-
tiveness of the safety system by trained individuals. Siemens AG, its subsidia-
ries and affiliates (collectively "Siemens") are not in a position to evaluate all of
the characteristics of a given machine or product or machine not designed by
Siemens accepts no liability for any recommendation that may be implied or sta-
ted herein. The warranty contained in the contract of sale by Siemens is the sole
warranty of Siemens. Any statements contained herein do not create new war-
ranties or modify existing ones.
You can use the safety relays 3TK2827/28 in EMERGENCY STOP devices as per
DIN EN 418, in safety circuits as per and/or EN 60 204-1 (11.98), such as for
monitoring safety guards, or in circuits with controlled standstill requirement
(STOP Category 1). Depending on the external circuitry, you can use this device
to install Safety Category 4 instantaneous release circuits and Safety Category 3
delayed release circuits according to DIN EN 954-1.
Functions and connections
The 3TK2827/28 safety relays possess two delayed and two instantaneous
release circuits as NO circuits and one instantaneous signal circuit as NC circuit.
Five LEDs indicate the operating status and the functions.
The internal redundant safety relays, the electronics and the operated motor
contactors are tested for proper functioning when the EMERGENCY STOP button
or the limit switch button is unlatched, and when ON circuit Y33, Y34 is closed.
On the 3TK2827 (monitored start), the ON circuit Y33, Y34 is checked for short-
circuit. This means that a fault ist detected when Y33, Y34 is closed before the
EMERGENCY STOP button is closed.
Operating voltage A1
The PE terminal should only be
connected if ground fault monitoring is
at Y33, 34
for 2 x 1.5 mm
Dimension drawings (dimensions in mm)
Installation / Cage Clamp
Internal circuit: ¿ power pack, À PTC fuse, Á control logic,
Â Channel 1, Ã Channel 2, Ä Channel 1 (t), Å Channel 2 (t)
3TK2827, Monitored start for EMERGENCY STOP
Safety category 2*
Safety category 3
Follow connection notes
given in Fig. VIII!
Release circuit 1, instantaneous
Release circuit 2, instantaneous
Signal circuit, instantaneous
Release circuit 1, delayed (t)
Release circuit 2, delayed (t)
3TK2827 / 3TK2828
Jumper from Y11 to Y12
Jumper from Y21 to Y22
or Jumper to
EMERGENCY STOP circuits
at Y10, Y11
Jumper from Y10 to Y11
EMERGENCY STOP circuits
at Y11, Y12 and Y21, Y22
max. 1000 m (total length for sensors)
Order No.: 3ZX1012-0TK28-5CA1
3TK2828, Autostart for Guard door monitoring
Safety category 2*
Fig. VII: Safety category 3
*) This wiring example only satisfies category 2 according to EN 954-1 if a warning is automatically
generated when the actuator fails or the machine control initiates a safe state. Otherwise an alternative
shut-down method is required.
Permissible ambient temperature T
Degree of protection to EN 60 529
Rated insulation voltage U
Rated impulse withstand voltage U
Rated control supply voltage U
AC/DC operating range
Shock resistance (half-sine) as per IEC 60068 8 g/10 ms
Recovery time after
Release time after EMERGENCY STOP
as per IEC 60947-5-1
Continuous current I
Signal circuit and
Control supply voltage
Be sure to fit the specified fuses. Otherwise safe interruption in
the event of a fault cannot be guaranteed.
For further data and accessories see Catalog.
DIN EN 60947-5-1 (08.00)
FK 1 & 2 open,
FK 1 (t) & FK2 (t)
• Relay fusion-welded
• Motor contactor fusion-welded
• Defect in electronics
• Short-circuit in ON circuit
Cross or ground faults in
EMER-GENCY STOP circuit (min.
fault current I
= 0.5 A; PTC fuse
trips) or supply voltage missing.
25 to +60 °C/
40 to +80 °C
24 V DC, 24 V AC, 115 V AC, 230 V AC
3 W/4 VA
0.85 to 1.1 x U
Restart only possible after this
0.05 to 3 s or 0.5 to 30 s adjustable
max. 80 ms
Rated operational current I
on loading of instantaneous / delayed
release circuits (A)
gL(gG) 6 A / quick response 10 A
gL(gG) 2 A