Lesson 1.5: Emergency Glass Breaks

Lesson 1.5: Emergency Glass Breaks (EGB)

⚡ The Logic (Mermaid)

flowchart LR
    PSU("12V/24V PSU 
+V")
    subgraph RLY["Door Relay"]
        direction TB
        NO
        COM
        NC
    end  
    subgraph DINPUT["Door Input Terminals"]
        direction TB
        TONG("Tong Input")
        ZV("0V")
    end
    subgraph GB["Emergency Glass Break Unit"]
        direction TB
        EGB("1st NC Contact
(Breaks Lock Power)")
        EGB1("2nd NC Contact
(Reports EGB Status)")
    end
    PSU --- COM
    NC ---|"NC
Always Powered"| EGB
    EGB --- LOCK("Fail-Safe EMLock")
    LOCK --- GND("PSU 0V")
    EGB1 --- TONG
    EGB1 --- ZV

Hardware Landmark: Emergency Glass Break (EGB)

!300
Above: A standard green Emergency Glass Break unit. Manual activation physically breaks the lock power circuit.

🧠 The Concept

The Emergency Glass Break is a life-safety device. It MUST physically break the power to the lock, even if the controller software crashes. This is a "hard-wired" safety bypass for Fail-Safe doors (Maglocks).

🛠️ Hands-on Steps

Series Wiring: Always wire the EGB in series with the positive power wire going to the lock.
Monitoring: Most EGBs have a second set of contacts. Wire these to a Controller Input so the security system knows the glass has been broken.
Testing: Use the "Test Key" provided with the EGB to verify the door releases without breaking the actual plastic/glass.

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