ABB REL 352, Instruction Manual

Page: 156 / 163

I.L. 40-201.9 Power Automation and Protection Division
K-4 REL 352 Version 1.00
Please note that the information applies to LP and LN as well.
IKEY
i
i
Figure 3. Square Wave Duration - 60 Hz
60 Hz
Where r = IKEY/IT [rms]
i.e. IKEY = 0.5,
IT = 5 A
IKEY time = t (r) *1000
IT computation
IT = C0xI0+C1xI1+C2xI2
Example:
Applying balanced 3-phase fault of
5A rms requires C1=1 to obtain IT
of 5A rms
I< t(r) >I
f : = 60 r: 0 0.05..1 2
⋅
, =
t r
( )
:
1
2 f
⋅
----------
r
2
-------
 
 
asin
f
π ⋅
---------------------- =
i: 0..48 =
X
i
: i
π
24
------
⋅
 
 
sin =
y
i
: i.
π
24
------
π
6
--- +
 
 
sin =
r
t(r)•1000
0 8.33
0.05 8.15
0.1 7.96
0.15 7.77
0.2 7.58
0.25 7.39
0.3 7.2
0.35 7.01
.04 6.81
0.45 6.62
0.5 6.42
0.55 6.21
0.6 60.1
0.65 5.8
0.7 5.59
0.75 5.37
0.8 5.15
0.85 4.90
0.9 4.67
0.95 4.43
1 4.17
1.05 3.89
1.1 3.61
1.15 3.3
1.2 2.96
1.25 2.58
1.3 2.15
1.35 1.6
1.4 0.75
>> <<[msec]