Stem NC97 Operating Instructions

Operating instructions for safety control unit mod. NC97-NC9701
These operating instructions are valid only in
conjunction with the manuals of the relative sensors
used, which can be downloaded from the main
manuals section at the following link
https://www.stemsrl.it/it/downloads/.
Refer to the table below for the type of STEM sensors
paired with the control unit.
Sensor code Type
Reed
Nxxx Hx Nxxx FP, Nxxx FH
coded
Reed
Axxx 2L, Dxxx 2L, Exxx 2L
non-coded
Hall
NxxH G3
coded
RFID + Hall
N5xx RF G02
coded
Correct use
Safety sensors are a series of safety devices suitable for
monitoring the status of the removable safety guards on
the machine.
They ensure that dangerous work on machines can only be
carried out if the safety guards are closed.
A stop command is only activated if a safety guard is
opened while the machine is running.
SAFETY PRECAUTIONS
!
Safety devices perform a personal protection function; they
must not be bypassed (by shorting the contacts), moved,
removed or otherwise rendered ineffective.
Incorrect installations or manipulations can cause serious
personal injury.
The manufacturer or installer of the machine is responsible
for its correct and safe operation.
The auxiliary output 41/42/54 provides information on the
status of the device, therefore it must not be used in any
way as a safety output.
The NC97 and NC9701 are not suitable for operation in the
presence of ionizing and non-ionizing radiation (X-rays,
microwaves, lasers, ultraviolet rays) (EN 60204-1, §4.4.7).
Operation
The NC97 and NC9701 safety control unit are able to
control the status NO+NO (with open guard) separated
inputs (magnetic safety sensors, emergency buttons,
mechanical safety switches, safety interlocks for movable
guards): the output is activated by pressing and releasing
the START button (reset) only if the two NO inputs are
activated (contacts closed or transistor outputs activated).
The switching of even just one input determines a safety
situation, placing the safety outputs in the open state and
preventing them from closing even after the input has been
switched again and the START button (reset) is pressed.
If the units are used to control emergency buttons,
following the intervention of the device, their reset must not
involve restarting the machine (EN 60204-1, §9.2.3.4.2,
EN ISO 13850, §4.1.4).
If the units are used to control the interlocking sensors of
movable guards, the reclosing or reactivation of a guard
must not start a dangerous operation of the machine
(EN 60204-1, §9.3.1).
By short-circuiting terminals Y1-Y2-X1, the device is reset
automatically (in this case A2 must not be connected to the
start circuit);
the behavior of the machine when the device is reset - i.e.
the non-automatic restart of the dangerous elements of the
machine - depends on the implementation method of the
machine control circuit according to the risk assessment
carried out by the user.
If the emergency stop control has only one NC contact,
connect it between the positive terminal (L+) of the power
supply and terminal A1; if no safety sensor is used,
terminals S11-S12 and S21-S22 must be bridged.
Safety category 4 is guaranteed only if (see connection
drawing):
- two relays are used to interrupt the load, each of which is
connected to an output of the control unit.
- the NC auxiliary contacts of the relays controlled by the
control unit (Ka, Kb) are inserted in the feedback loop
(X1-S12).
Safety is ensured by the use of guided contacts,
redundancy and the contact interconnection scheme.
It is the responsibility of the user to choose suitable
components for safety applications, for example guided
contact relays.
Assembly
The installation must be carried out only by authorized
personnel.
The NC97 and NC9701 must be installed in a suitable area
of use (electrical cabinet, junction box, at least IP54) by
fixing it to a standard 35 mm DIN omega rail.
Operative
Electric connections
intructions
Coded sensors
The electrical connections must only be made by
manual
authorized personnel following the instructions on the
Non-coded
EN ISO 13849-1 and EN ISO 13849-2.
sensors manual
Hall safety sensors
All electrical inputs must be isolated from the mains supply
manual
or via a separate safety transformer in accordance with EN
RFID sensors
IEC 61558-2-6 with limited output voltage in the event of a
manual
fault, or by an equivalent removable mechanism.
The power supply must be permanently connected using a
cable with a maximum length of 10 m;
the sensors must be connected to the unit with cables of a
maximum length of 30 m.
The relay outputs have a maximum current of 3A; the
power supply connected to these outputs must be
protected against overcurrents by devices suitable for the
loads to be protected. All output contacts must have an
adequate protection circuit for inductive and capacitive
loads.
All inductive and capacitive loads connected to the power
supply must be connected to an appropriate interference
suppressor.
Setup
If the controller appears to be inoperable when mains
voltage is applied (the green PWR LED does not light up) it
must be returned sealed to the manufacturer.
Check that the safety outputs switch (see LED table) by
activating the inputs and pressing the START (reset)
button.
Table of LEDs
Function
Power supply
Outputs 13-14/23-24 : OPEN
Output 41-42 : OPEN
Output 41-54 : CLOSED
Outputs 13-14/23-24: CLOSED
Output 41-42 : CLOSED
Output 41-54 : OPEN
Maintenance and Inspection
The correct functioning of the control unit must be checked
by the operator and/or by the control circuit of the machine
in which it is used at each installation, new wiring or
modification of the configuration of the sensors and in any
case on a periodic basis (at the beginning of each shift or
at the latest within the 8 hour period) by verifying the
following :
- correct commutation of each single sensor
checking that:
a) at the opening of the single sensor/guard the safety
outputs (13-14 / 23-24) open
b) when closing the same sensor/guard the safety
outputs (13-14 / 23-24) close following any start
command
- safe fixing of the components
- correct fastening of the connections.
The device monitoring function is performed at each
intervention of the device itself.
If with all the guards closed and following a possible start
command, the control unit does not activate its safety
outputs, do not switch the device off and on , then proceed
to check any open guards and carry out the checks
indicated above in point a ) and b).
In the event of failure or wear, the damaged system must
be replaced.
Warranty coverage is voided in the following
circumstances:
- if the instructions are not followed
- non-compliance with safety regulations
- installation and electrical connection not carried out by
authorized personnel
- failure to carry out the functioning checks.
- tampering with the product
Sensors and Magnetic Units installation
Install Sensor and Magnetic units so that:
- They are accessible for inspection work and for the
installation of spare parts.
- When the safety guard is closed, the active read
head and actuator area are exactly aligned
(see "Alignment between Sensors and Magnets"
in the sensor manual)
- The magnetic unit is inside the activation area
of the sensor when the safety guard is closed.
- A guide and an extra stop are inserted in the
mobile part of the safety guard.
- A stop mechanism is inserted on the protective doors
for closed position.
If several Sensor-Magnetic Unit pairs are mounted close
together, the switching distance is reduced according to
the distance between the pairs and the safety guard
material.
If Sensors and Magnetic Units are mounted on
ferromagnetic material, the activation distance is reduced.
The approach speed between the sensor and the magnet
must not be too slow, if the unit is working in automatic
start configuration.
To ensure that round Magnetic Units cannot rotate when
fixed to the protective doors, a 2 mm hole must be drilled
during installation for the anti-rotation pin that each
magnet is equipped with.
Connection diagram
Manual Start
Power supply
24 V
ac/dc
LED Color Status
PWR Green on
CH1 Green off
CH2 Green off
S21 S22
CH1 Green on
Sensor inputs
CH2 Green on
Feedback
control loop*
Automatic start
Feedback
control loop*
Timing diagram for manual start
S1
S2
avvio
13-14 / 23-24
Timing diagram for automatic start
S1
S2
13-14 / 23-24
Original
instructions
Start
Signal output
A1 A2 Y1 Y2 41 42 54
-
+
~ ~
K3
K1 K2 K1 K2
Safety
S11 S12 X1 13 14 23 24
outputs
L1
Ka
Kb
N
A2 Y1 Y2
-
~
S11 S12 X1
* If it is not necessary to
control the NC auxiliary
contacts of the relays via a
feedback loop, short-circuit
terminals S12 and X1.
t3 t3
t1 t1
(Y1- Y2 - X1 bridged)
t2 t3 t2 t3 t2
L
L2 L3
M
M
3
t3
t1
t3