Contact Input Configuration - GE D90 Plus Instruction Manual

CHAPTER 8: AUTOMATION

Contact input configuration

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D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Figure 330: Contact input and output assignments
All available contact inputs and output can be reassigned using the >> and << buttons.
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The D90 can monitor the status of up to 115 field contacts. Each input can be wetted
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from the D90 48 volt auxiliary supply or from an external power supply. Each digital
input has a dedicated delay timer for filtering of contact bouncing. The D90
detect an oscillating input via the chatter feature. Each contact input active impedance
circuitry to provide security against false turn-on of an input due to excessive stray
capacitance of field wiring.
A raw status is scanned synchronously for all contact inputs at the rate of 0.25 ms as
shown below. A new contact input state must be maintained for a user-programmable
debounce time for the D90
at 2.0 ms in the figure below; as such, the eighth sample validates the change of state
(mark 1 in the figure below). Once validated (de-bounced), the automation contact input
asserts a corresponding automation operand and logs an event (if event logging is
enabled).
A time stamp of the first sample in the sequence that validates the new state is used when
logging the change of the contact input into the event recorder (mark 2 in the figure
below).
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to validate the new contact state. The debounce time is set
AUTOMATION INPUTS AND OUTPUTS
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can also
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