Functioning
The NC88 Module can control the state of two Reed magnetic sensors : the
output is activated by pressing the START button only if the contacts of two
sensors are closed. The opening of even only one input contact (S1 and/or S2),
leads to a safety situation, by putting the safety outputs in open state and by
preventing the closing even after the re-closing of the contact and the pressure of
the START button.
For automatic start, see connection diagram.
Input channels work on opposite potentials (S11
-
; S21
+
).
It's available an input (X1-X2) for feedback with contactors or external relays (see
Ka and Kb on the connection diagram).
The control unit has a dedicated circuit to guarantee the its correct functionality
in case of short voltage dips
The safety is ensured by using guided contacts, by the redundance and by the
interconnection schematic of the contacts.
The responsibility to choose the adequate components for safety applications, for
example guided contacts safety relays, falls to the user.
Assembly
Installation must be performed by authorized personnel only.
The NC88 control unit must be assembled in a suitable operating area (switch
cabinet, protective housing).
The unit is installed by clipping it to a standard 35 mm top-hat rail.
Safety Precautions
The manufacturer of a machine or installation is responsible for correct and
safe overall function.
Auxiliary output Y1/Y2 and Y2Y3 are optoinsulated and gives informations
about the state of the device; it must not be used as a safety output.
NC88 is not proper for the operation in presence of ionizing and not ionizing
radiations (rays X, microwaves, laser, ultraviolet rays)
(CEI EN 60204-1:2006, §4.4.7).
Operating instructions for safety control unit mod. NC8 8
STEM S.r.l. via della Meccanica, 2 I-27010 Cura Carpignano Pavia Italia Tel. +39 0382 583011 Fax +39 0382 583058 www.stemsrl.it [email protected]
!
Description
The NC88 safety relay is created for use in safety circuit intended by
EN 81-20:2014, EN 81-50:2014
This module is based upon the use of guided-contact safety relays.
!
Electrical Connection
Electrical connection must be performed by authorized personnel only.
All the electrical inputs must either be isolated from the mains supply by a
separate coils safety transformer in accordance with EN IEC 61558-2-6
with limited output voltage in the event of a defect or by another equivalent
movable mechanism.
The outputs of the relays have a maximum current of 3 A; the supply
connectedto the outputs must be protected from overcurrents by devices
adequate to the loads that have to be protected.
All the output contacts must have an adequate protective circuit for capacitive
and inductive loads.
If a common power supply is used, all the inductive and capacitive loads (e.g.
relay contactors) connected to the power supply must be connected to
appropriate interference suppressors.
Service and Inspection
The correct functioning of the NC88 safety unit must be controlled by the
operator and/or by the control circuit of the elevator in which it is used
periodically, by checking:
- Correct switching function of each sensor by checking:
a) that the opening of the single sensor will cause the opening of the safety
outputs (13-14 / 23-24)
b) that the closure of the same sensor will cause the closing of the safety
outputs (13-14 / 23-24) as a result of a startup command
- secure mounting of components
- correct connection fixing.
The monitoring function of the unit is done at every switching cycle. If the
elevator is in a door zone and following the eventual start command, the
safety device does not activate its safety outputs, do not turn off and turn on
the device, then proceed to the checking of the possible sensor fault and
perform the above tests in point a) and b).
In the event of damage or wear and tear, the damaged system component
must be replaced.
Liability coverage is void under the following circumstances:
- if instructions are not followed
- non-compliance with safety regulations
- installation and electrical connection not performed by authorized personnel
- non-implementation of functional checks.
Setup
If the control unit does not appear to function when operating voltage is
applied (yellow LED does not light up), the unit must be returned unopened to
the manufacturer.
Check whether the safety outputs are being switched (see LED display) by
activating the two inputs S1, S2 and START.
Connections
Y2
Signal outputs
Power supply
24 V ac/dc
A1 A2 Y1
Ka
Start
button
(reset)
Feedback
control loop
N
M
3
K1
23
X1
Y3 Y4
K1
X2 13 14
L3
L1L2
24
Inputs(Reed sensors)
S22
S21
K2
K3
K2
S11S12
K3
K3
Safety
outputs
Kb
S2
S1
L
+ -
Automatic start connections
1) Automatic start with the sync time between inputs infinite
(ONLY for use in the lift industry - EN81-20: 2014).
Reed switch sensors ID, IS and IZ.
In this configuration the inputs synchronization time among the closing of IZ
and one between IS and ID, it is endless, but a correct closing sequence has
to be respected: the first contact to be closed is IZ, then IS or ID.
This configuration cannot be used with Hall effect sensors.
S12
S11
S22
S21
X1 X2
GND
+
+
NOT CONNECTED
IZ
IS
ID
Feedback loop of the
external contactor
(short-circuit if not used)
MD
N.O
.
N.O
.
MZ
N.O
.
MS
ID
IZ
IS
2) Short-circuit of S33 and S34; in this case there will be a
synchronism time between inputs of 600 ms.
X1 X2
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