Siemens 7SR242 - Self-Monitoring and Virtual I;O

7SR242 Duobias Description Of Operation
©2010 Siemens Protection Devices Limited Chapter 1 Page 19 of 52
Event
Output 1
Min Operate Time
Hand Reset
BO 1 hand reset
S
R
Q
OUTPUT CONFIG>
OUTPUT MATRIX
(Or gates)
Logic signals,
e.g. '51-1'
Reset LEDs & Outputs (TEST/RESET key, Binary Input, Data Comms)
&
&
&
1
1
Event
Output n
BO n hand reset
S
R
Q
&
&
&
1
1
BO 1
BO n
OUTPUT
CONFIG>
BINARY
OUTPUT
CONFIG
OUTPUT
CONFIG>
BINARY
OUTPUT
CONFIG
Figure 2-3 Binary Output Logic
2.10 Virtual Input/Outputs
The relays have 16 virtual input/outputs, these are internal logic states. Virtual I/O is assigned in the same way as
physical Binary Inputs and Binary Outputs. Virtual I/O is mapped from within the INPUT CONFIG > INPUT
MATRIX and OUTPUT CONFIG > OUTPUT MATRIX menus.
The status of virtual I/O is not stored during power loss.
2.11 Self Monitoring
The relay incorporates a number of self-monitoring features. Each of these features can initiate a controlled reset
recovery sequence.
Supervision includes a power supply watchdog, code execution watchdog, memory checks by checksum and
processor/ADC health checks. When all checks indicate the relay is operating correctly the ‘Protection Healthy’
LED is illuminated.
If an internal failure is detected, a message will be displayed, also an event will be generated and stored. The
relay will reset in an attempt to rectify the failure. This will result in de-energisation of any binary output mapped to
‘protection healthy’ and flashing of the protection healthy LED. If a successful reset is achieved by the relay the
LED and output contact will revert back to normal operational mode, and the relay will restart.
2.11.1 Protection Healthy/Defective
A normally open contact can be used to signal protection healthy. When the relay has DC supply and it has
successfully passed its self-checking procedure then the Protection Healthy contacts are made.
A normally closed contact is used to signal protection defective. When the DC supply is not applied to the relay or
a problem is detected within the relay then this output is de-energised and the normally closed contacts make to
provide an external alarm.
An alarm can be provided if the relay is withdrawn from the case. A contact is provided in the case at positions
25-26 of the PSU module, this contact closes when the relay is withdrawn.