Micom P634 - Page 201

Address Description Range of Values
PS1 PS2 PS3 PS4
072 149 073 149 074 149 075 149 REF_1: Operating mode
PSx
Low imped. / sum(IP)
(default)
Low imped. / IP,max
High impedance
072 169 073 169 074 169 075 169 REF_2: Operating mode
PSx
Low imped. / sum(IP)
(default)
Low imped. / IP,max
High impedance
072 049 073 049 074 049 075 049 REF_3: Operating mode
PSx
Low imped. / sum(IP)
(default)
Low imped. / IP,max
High impedance
3.22.4.1 “Low imped. / sum(IP)” Operating Mode
From the amplitude-matched resultant currents I_
am,N ,a
and I_
am,Y ,a
, the
differential and restraining currents are calculated as follows:
I
d,N,a
=
|
I_
am,N ,a
+ I_
am,Y ,a
|
I
R,N ,a
=
|
I_
am,N ,a
|
Again, the equation for the differential current applies under the condition of
uniformly defined current arrows relative to the protected object. Both current
arrows point either towards the protected object or away from it.
Fig. 3-101, (p. 3-146) shows the tripping characteristic of the ground differential
protection function. The characteristic equation is as follows:
I
d,N,a
I
ref
=
I
diff >,N,a
I
ref ,N,a
+ 1.005 ⋅
I
R,N ,a
I
ref ,N,a
with
I
diff >,N,a
: setting at REF_1: Idiff> PSx
3 Operation P634
P634/EN M/R-42-A // P634‑311‑653 3-145