ABB 615 Series ANSI, Technical Manual

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Section 5
Protection related functions
615 series ANSI 403
Technical Manual
5.5.2 Function block
Figure 203: Function block
5.5.3 Functionality
The arc flash detector AFD detects arc situations in air insulated metal-clad switchgears
caused by, for example, human errors during maintenance or insulation breakdown during
operation.
The function detects light from an arc either locally or via a remote light signal. The
function also monitors phase and ground currents to be able to make accurate decisions on
ongoing arcing situations.
The function contains a blocking functionality. Blocking deactivates all outputs and resets
timers.
5.5.4 Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are Enable and Disable.
The operation of the arc flash detector can be described by using a module diagram. All
the modules in the diagram are explained in the next sections.
Figure 204: Functional module diagram. I_A, I_B and I_C represent phase currents.
Level detector 1
The measured phase currents are compared phase-wise with the set Phase pickup value . If
the measured value exceeds the set Phase pickup value , the level detector reports the
exceeding of the value to the operation mode selector.