Measurements and Recording
P74x/EN MR/N
1, P742, P743
(MR) 8-
The Event Value is a 12, 16, 24 or 32-bit word showing the status of the opto inputs, where
the least significant bit (extreme right) corresponds to opto input 1 etc. The same
information is present if the event is extracted and viewed via PC.
2.3.2 Change of state of one or more output relay contacts
If one or more of the output relay contacts have changed state since the last time that the
protection algorithm ran, then the new status is logged as an event. When this event is
selected to be viewed on the LCD, three applicable cells will become visible as shown below:
Time & date of event
“OUTPUT CONTACTS #”
“Event Value 1010101010101010”
Where # = 1 or 2 depending upon which group of 16 output relays is selected. In the case of
P74x relay, however, the value will always be “1” as it is impossible to have more than 16
output relays.
The Event Value is a 12, 16, 24 or 32 bit word showing the status of the output contacts,
where the least significant bit (extreme right) corresponds to output contact 1 etc. The same
information is present if the event is extracted and viewed via PC.
2.3.3 Relay alarm conditions
Any alarm conditions generated by the relays will also be logged as individual events. The
following table shows examples of some of the alarm conditions and how they appear in the
event list:
Alarm Condition Event Text Event Value
Battery Fail Battery Fail ON/OFF Bit position 0 in 32 bit field
Field Voltage Fail Field Volt Fail ON/OFF Bit position 1 in 32 bit field
The previous table shows the abbreviated description that is given to the various alarm
conditions and also a corresponding value between 0 and 31. This value is appended to
each alarm event in a similar way as for the input and output events previously described. It
is used by the event extraction software, such as S1, to identify the alarm and is therefore
invisible if the event is viewed on the LCD. Either ON or OFF is shown after the description
to signify whether the particular condition has become operated or has reset.
2.3.4 Alarm List
Alarm P741 P742 P743
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