GFK-2956A November 2017 55
7.8 Dual-channel Safety Door Monitoring, Spring-operated
Interlock with Manual Reset and Emergency Stop
Note: All example applications shown are proposals without warranty. In any case the operator has
to perform a safety review of the entire site.
When the emergency stop button is pushed, the EP-19xx switches off the 24-V supply for the
modules (switchable modules refer to the section, General Contact Information) within the safety
segment and thus also contactors K3 and K4. The failure of a switching element in the emergency
stop button or the safety door contact as well as a cross-circuit in their supply lines does not result in
the failure of the emergency stop mechanism and is detected within the fault-reaction time.
A stop is performed by switching off K3 and K4 via the PLC. After the motor comes to a stop, as
observed by the zero-speed monitor, the spring-operated interlock can be activated via the
unlocking button and the safety door can be opened. When the power supply is turned off, the safety
door cannot be opened if the locking mechanism is engaged. We recommend using switches with
mechanical unlocking capabilities.
The EP-19xx switches on the 24-V supply for the following modules within the safety segment if:
• Emergency stop button is unlocked
• Safety door is closed
• Locking mechanism is engaged
• Feedback circuit (NC contacts of K3 and K4) is closed
• Start push button has been pushed and released again
Contactors K3 and K4 are controlled by the PLC and can switch on as soon as the EP-19xx has
switched on the 24-V supply.
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