Micom P721, Technical Manual

Page: 187 / 334

Application Guide P72x/EN AP/C21
MiCOM P721/P723 Page 51/52
FIGURE 37 shows the CT requirements when the P72x is used in a REF/BEF application
and the Measurement Mode is set to Sample. The maximum K factor is approximately 0.91.
The operating time when V
K
/V
S
= 4 is 55 ms and K is approximately 0.76.
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 2 4 6 8 10 12 14 16
Vk/Vs
K
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
a
ver
ag
e
o
p
. ti
m
e
(s)
K average op. time
stable
unstable
FIGURE 37: CT REQUIREMENTS- REF/BEF- SAMPLE MODE
13.2 Busbar application
The operating characteristics shown in FIGURE 38, FIGURE 39 and FIGURE 40 are valid
when 5
≤
X/R
≤
120, 0.5
≤
If
≤
50 and [87N] Threshold I Diff = 0.1In.
FIGURE 38 shows the CT requirements when the P72x is used in a busbar application and
the Measurement Mode is set to Fourier. The maximum K factor is approximately 0.98.
When VK/VS is 4, the average operating time is 30 ms and K is approximately 0.89. The
user should consider these characteristics when selecting Vk/Vs, the K factor and the
average operating time as explained in the previous setting examples.
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0 2 4 6 8 10 12 14 16
Vk/Vs
K
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
aver
ag
e o
p
. t
im
e (
s)
K average op. time
unstable
stable
FIGURE 38: CT REQUIREMENTS- BUSBAR - FOURIER MODE