3.12.6.1 Measured Current Values
The measured current values are displayed both as per-unit quantities referred
to the nominal quantities of the P634 and as primary quantities. To allow display
in primary values, the primary nominal current of the system current transformer
should be set in the P634.
3.12.6.2 Display of Delayed and Stored Maximum Phase Currents
Delayed Maximum Phase Current
The P634 offers the option of a delayed display of the maximum value of the
three phase currents (thermal ammeter function). The delayed maximum phase
current display is an exponential function of the maximum phase current I
P,max
(see upper curve in Fig. 3-45, (p. 3-77)). The time after which the delayed
maximum phase current display will have reached 95 % of maximum phase
current I
P,max
is set at MAIN: Settl. t. IP,max,del.
Stored Maximum Phase Current
The stored maximum phase current follows the delayed maximum phase current.
If the value of the delayed maximum phase current is declining, then the highest
value of the delayed maximum phase current remains stored. The display
remains constant until the actual delayed maximum phase current exceeds the
value of the stored maximum phase current (see middle curve in Fig. 3-45, (p. 3-
77)). The stored maximum phase current is set to the actual value of the
delayed maximum phase current at MAIN: IP,max p.u.,stored a, using end a
as an example (see lower curve in Fig. 3-45, (p. 3-77)).
P634 3 Operation
3-76 P634/EN M/R-42-A // P634‑311‑653
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