2 Engineering
2.2 Safety shutdown with reduced lifespan (EMS-DOS-…/EMS-ROS-…)
Elektronischer Motorstarter EMS/Electronic Motor Starter EMS 04/15 MN03407009Z-DE/EN www.eaton.com 43
2.2 Safety shutdown with reduced lifespan (EMS-DOS-…/EMS-ROS-…)
The simplest way to integrate an EMS electronic motor starter into an emer-
gency stop circuit is shown in Section “Single-channel switching and control
current path emergency stop (reduced lifespan)” below. In this circuit, the
supply voltage is cut off with a safety relay as soon as the emergency stop
pushbutton is pressed. The motor voltage is guaranteed to be cut off 25 ms
after the rated control voltage is cut off.
Since the electronic motor starter's supply voltage is only cut off with a sin-
gle-channel configuration, this type of installation is only permissible for SIL 3
(cat. 3, cat. 4) if cross-fault fault exclusions are allowed. This will be the case,
for example, when the electronic motor starter and the safety relay are
installed in the same control panel. If this type of fault exclusion is not per-
missible, the supply voltage must be cut off with a dual-channel or 2-pole
configuration.
The following examples of circuits, used to implement an electronic motor
starter safety shutdown mechanism, cut off the electronic motor starter's
supply voltage. When using this approach, always bear in mind that cutting
off the supply voltage while the motor is being driven will always result in
additional wear to the electronic motor starter. Because of this, these two
circuits should only be used if no more than 10,000 shutdown operations are
expected throughout the starter's entire service life!
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