Binary Outputs; Leds - Siemens Argus 7SR21 Technical Manual

1.3

Binary Outputs

Binary Outputs are mapped to output functions by means of settings. These could be used to bring out such
digital signals as trips, a general pick-up, plant control signals etc.
All Binary Outputs are Trip rated
Each can be defined as Self or Hand Reset. Self-reset contacts are applicable to most protection applications.
Hand-reset contacts are used where the output must remain active until the user expressly clears it e.g. in a
control scheme where the output must remain active until some external feature has correctly processed it.
Case contacts 26 and 27 will automatically short-circuit when the relay is withdrawn from the case. This can be
used to provide an alarm that the Relay is out of service.
Notes on Self Reset Outputs
With a failed breaker condition the relay may remain operated until current flow in the primary system is
interrupted by an upstream device. The relay will then reset and attempt to interrupt trip coil current flowing
through an output contact. Where this level is above the break rating of the output contact an auxiliary relay with
heavy-duty contacts should be utilised.
1.4

LEDs

Output-function LEDs are mapped to output functions by means of settings. These could be used to display such
digital signals as trips, a general pick-up, plant control signals etc.
User Defined Function Key LEDs are used to indicate the status of Function Key operation. These do not relate
directly to the operation of the Function Key but rather to its consequences. If a Function Key is depressed to
close a Circuit-Breaker, the associated LED would show the status of the Circuit-Breaker closed Binary Input.
Each LED can be defined as Self or Hand Reset. Hand reset LEDs are used where the user is required to
expressly acknowledge the change in status e.g. critical operations such as trips or system failures. Self-reset
LEDs are used to display features which routinely change state, such as Circuit-Breaker open or close.
The status of hand reset LEDs is retained in capacitor-backed memory in the event of supply loss.
Each LED can be assigned as red, yellow or green in colour. There are two methods for doing this: -
1) In the LED Matrix tab, to assign the LED as a red colour select a box on the red row. To assign the
LED as a green colour select a box on the green row. To assign the LED as a yellow colour, select
boxes on both the red and green rows.
NB: If there are no boxes selected the LED will not illuminate.
Figure 1.4-1
© 2013 Siemens Protection Devices Limited
LED configuration via the LED Matrix tab
7SR210 & 7SR220 Applications Guide
Page 9 of 48