D25
User's Manual
GE Grid Solutions
108
994-0081-3.00-21
GE Information
Using Current-Monitored Digital Outputs
Current-
Monitored
Digital Outputs
D25s equipped with a high-current control card are provided with 8 digital
outputs that have current monitoring. The last 8 of the 32 points on the card
(i.e. 25 – 32) are designated as the current-monitored points.
By default, current monitoring and seal-in is enabled in the D25
configuration. A point enabled for monitoring and seal-in operates according
to the following rules:
Rules Current-
Monitored
Digital Outputs
•
Only pulse type commands are accepted.
•
If the current across the relay contacts exceeds the relay breaking current during
the pulse operation, and clears before the pulse duration expires, the relay will
open normally when the pulse duration expires and no alarm will be raised.
•
If current in excess of the relay breaking current is detected across the contacts
of the point when the pulse duration has expired, the contact will remain closed
and a current seal-in digital input alarm will be activated to indicate the
condition. The local/remote LEDs on the front of the D400 will begin flashing as
well to indicate the presence of the condition. The alarm points are placed at
digital inputs 148 to 155 in the D25 Plant I/O DCA (actual point number may be
offset if there are DCAs placed before Plant I/O in the configuration).
•
While a contact is sealed closed, additional control requests on the point are
rejected. If the board is placed in local mode via the local/remote switch on the
front of the D25, the contact will remain sealed.
•
The contact will remain sealed closed until the excessive current clears or an
override command is sent. If the excessive current clears, the relay will open
automatically. No additional user input is required. Alternatively, an override
command may be sent via a digital output. These digital outputs are placed at
digital outputs 36 to 43 in the D25 Plant I/O DCA (actual point number may be
offset if there are DCAs placed before Plant I/O in the configuration). If a
control operation is sent to the override digital point for a sealed-in digital
output, then the relay seal-in will be overridden and the relay opened. This may
cause damage to the high-current control card if the excessive current is still
present. The override points remain online even if the control is placed in local
mode, to ensure that the option to override a sealed-in relay is always available.
•
A current seal-in digital input alarm that is active due to seal-in will clear when
the relay contact opens, whether due to clearing of the current or do to an
override command being sent.
•
D25 Plant I/O DCA will reject control requests sent to the seal-in override digital
output for a point not under seal-in.
Summary of Contents for D25
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