Programmable Pushbuttons - GE 845 Instruction Manual

CHAPTER 4: SETPOINTS

Programmable Pushbuttons

845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
The user-programmable pushbuttons provide an easy and error-free method of entering
digital state (on, off) information. Three pushbuttons are available for programming.
Each pushbutton asserts its own ON and OFF FlexLogic operands (for example,
PUSHBUTTON 1 ON and PUSHBUTTON 1 OFF). These operands are available for each
pushbutton and are used to program specific actions. Each pushbutton has an associated
LED indicator. By default, this indicator displays the present status of the corresponding
pushbutton (ON or OFF).
The activation and deactivation of user-programmable pushbuttons is dependent on
whether latched or self-reset mode is programmed.
LATCHED MODE:
In Latched Mode, a pushbutton can be set (activated) by directly pressing the associated
front panel pushbutton. The pushbutton maintains the set state until deactivated by a
Reset command or after a user-specified time delay. The state of each pushbutton is
stored in non-volatile memory and maintained through loss of control power.
The pushbutton is Reset (deactivated) in Latched Mode by directly pressing the associated
active front panel pushbutton. It can also be programmed to Reset automatically through
the PB 1 AUTORESET and PB 1 AUTORESET DELAY settings. These settings enable the auto-
reset timer and specify the associated time delay. The auto-reset timer can be used in
select-before-operate (SBO) switching device control applications, where the command
type (CLOSE/OPEN) must be selected prior to command execution. The selection must
Reset automatically if control is not executed within a specified time period.
SELF-RESET MODE:
In Self-reset mode, a pushbutton remains active for the time it is pressed (the pulse
duration) plus the Dropout time specified in the PUSHBTN 1 DROPOUT TIME setting. The
pushbutton is Reset (deactivated) in Self-reset mode when the dropout delay specified in
the PUSHBTN 1 DROPOUT TIME setting expires.The pulse duration of the pushbutton must
be at least 50 ms to operate the pushbutton. This allows the user-programmable
pushbuttons to properly operate during power cycling events and various system
disturbances that may cause transient assertion of the operating signals.
The operation of each user-programmable pushbutton can be inhibited through the
PUSHBTN 1 LOCK setting. If locking is applied, the pushbutton ignores the commands
executed through the front panel pushbuttons. The locking functions are not applied to the
auto-reset feature. In this case, the inhibit function can be used in SBO control operations
to prevent the pushbutton function from being activated and ensuring "one-at-a-time"
select operation.
The locking functions can also be used to prevent accidental pressing of the front panel
pushbuttons.
Pushbutton states can be logged by the Event Recorder and displayed as Target
Messages. In latched mode, user-defined messages can also be associated with each
pushbutton and displayed when the pushbutton is ON or changing to OFF.
DEVICE
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