Connection Example; Function Of The Standstill Monitor Moc3Za; Fig. 2: Connection Example Of The Standstill Monitor Moc3Za; Fig. 3: Function Diagram Moc3Za - SICK MOC3ZA Notice D'instructions

Operating instructions
MOC3ZA
Fig. 2: Connection example
of the Standstill Monitor
MOC3ZA
Fig. 3: Function diagram
MOC3ZA
8014608/1DS0/2022-02-16
Subject to change without notice
Product description
3.3.1

Connection example

3.4

Function of the Standstill Monitor MOC3ZA

The supply voltage for the device is connected to terminals A1/A2; the PWR LED
illuminates  Green. In case of undervoltage the safety outputs on the device will not be
enabled.
If the semiconductor application diagnostics outputs are used, then a supply voltage
(24 V DC) must also be connected to the terminals A3 and A4.
An electric motor connected to the measurement channels L1/L2/L3 generates an
induced voltage due to the residual magnetism (remanence) as it coasts down (i.e. if the
supply voltage to the motor is switched off); the magnitude of the voltage is proportional to
the rotational speed of the motor.
This voltage is evaluated redundantly by the Standstill Monitor MOC3ZA. For this purpose
the measurement inputs L2 and L3 are used; L1 is a common reference point. If the
voltage on both measurement inputs is below the voltage threshold U
detected.
If the voltage drops below the voltage threshold U
S1/X1 is closed and the standstill time t
safety contacts 13/14, 23/24 and 33/34 close and the contact on 41/42 opens.
At the same time the signal relay is energized (signal contacts 53/54 close), the
semiconductor output ON is switched on and the OUT LED illuminates  Green. While the
standstill time t elapses, the OUT LED flashes  Green.
s
If the voltage measured on the measurement inputs L1/L2/L3 exceeds the value for U
on one of the measurement channels (i.e. there is power flowing through the motor
connected or it is running under mechanical action), the output relay is switched off
immediately (the safety contacts 13/14, 23/24 and 33/34 open and the positively guided
N/C contacts 41/42 close). The signal relay drops out (signal contacts 53/54 open), the
semiconductor output ON switches off and the OUT LED illuminates  Yellow (U
exceeded).
© SICK AG • Industrial Safety Systems • Germany • All rights reserved
, the external device monitoring (EDM)
an
has elapsed, the output relay switches on. The
s
en
Chapter 3
set, standstill is
an
an
an
53