Operation P54x/EN OP/La4
MiCOM P543, P544, P545 & P546
(OP) 5-129
OP
Operation of the element will produce a time-delayed alarm visible on the LCD, an event
record and a DDB 294: CT Fail Alarm, with an instantaneous block (DDB 928: CTS Block)
for inhibition of protection elements see Figure 82 above.
Figure 83 Standard CTS
3.2.3 CTS blocking
The sta
ndard and differential methods will always block protection elements operating from
derived quantities: Broken Conductor, Earth Fault and Neg Seq O/C. The differential
method will also restrain the differential protection. Other protection functions such as DEF
can be selectively blocked by customizing the PSL, gating DDB 928: CTS Block (originated
by either method) or DDB 929 CTS Block Diff with the protection function logic.
3.3 Transformer magnetizing inrush detector
I
n section 1.1.4.1 Trans
former magnetizing inrush and High set differential setting it is
described how inrush is taking into account by the differential protection. As this inrush
restrain technique is only valid for differential protection, there is a need of a separate inrush
detector in order to prevent operation of other functions if needed.
The MiCOM P54x distance protection has been designed as a fast protection relay. It is
therefore not desirable that distance zones should be slowed by forcing them to wait for a
detection/no detection of transformer inrush current (in general applications). For this
reason, the relay has no second harmonic blocking of the distance elements in the standard
protection algorithms.
However should a user wish to employ, for example, a long Zone 1 reach through a
transformer, it is possible to implement harmonic blocking for magnetizing inrush current.
Provided that the Inrush Detection is Enabled, the user can then pick up the output of the
I(2)/I(1) detectors in the Programmable Scheme Logic. The user can then assign blocking
functions in the PSL as necessary, because as stated above this detector does not directly
route into the relay’s fixed logic.
3.4 Function keys
The P54x re
lays offers users 10 function keys for programming any operator control
functionality such as auto-reclose ON/OFF, earth fault1 ON/OFF etc. via PSL. Each function
key has an associated programmable tri-color LED that can be programmed to give the
desired indication on function key activation.
These function keys can be used to trigger any function that they are connected to as part of
the PSL. The function key commands can be found in the ‘Function Keys’ menu (see
Settings chapter, P54x/EN ST). In the ‘Fn. Key Status’ menu cell there is a 10 bit word
which represent the 10 function key commands and their status can be read from this 10 bit
word.
In the programmable scheme logic editor 10 function key signals, DDB 1096 - 1105, which
can be set to a logic 1 or On state, as described above, are available to perform control
functions defined by the user.
To Next Page
Loading...
