Siemens SIPROTEC 7SD610 User Manual

2 Functions
36
7SD610 Manual
C53000-G1176-C145-4
Usually, the internal burden of the current transformers is stated in the test report. If it
is unknown, it can be roughly calculated from the DC resistance R
i
of the secondary
winding.
P
i
≈ R
i
· I
N
2
The ratio between operational accuracy limit factor and rated accuracy limit factor n'/n
is set at address 251 K_ALF/K_ALF_N.
The CT error at rated current, plus a safety margin, is set at address 253 E%
ALF/ALF_N. It is equal to the „current measuring deviation for primary nominal current
intensity F1“ according to VDE 0414 / Part 1 or IEC 60044. It is
– 3 % for a 5P transformer,
– 5 % for a 10P transformer.
The CT error at rated accuracy limit factor, plus a safety margin, is set at address 254
E% K_ALF_N. It is derived from the number preceding the P of the transformer data.
Table 2-1 illustrates some usual protective current transformer types with their charac-
teristic data and the recommended settings.
Table 2-1 Recommended settings for current transformer data
1)
If n'/n ≤ 1.50, setting = calculated ratio; if n'/n > 1.50, setting = 1.50
With this data the device establishes an approximate CT error characteristic and cal-
culates the restraint quantity (see also Section 2.3).
Calculation example:
Current transformer 5P10; 20 VA
Transformation 600 A / 5 A
Internal burden 2 VA
Secondary lines 4 mm
2
Cu
Length 20 m
Device 7SD610 , I
N
= 5 A
Burden at 5 A, 0.3 VA
CT class Standard Error at rated current Error at rated
accuracy limit
factor
Recommended settings
Transforma-
tion ratio
Angle Address 251 Address 253 Address 254
5P IEC 60044-1 1,0 % ± 60 min ≤ 5% ≤ 1,50
1)
3,0 % 10,0 %
10P 3,0 % — ≤ 10 % ≤ 1,50
1)
5,0 % 15,0 %
TPX IEC 60044-1 0,5 % ± 30 min ε ≤ 10 % ≤ 1,50
1)
1,0 % 15,0 %
TPY 1,0 % ± 30 min ε ≤ 10 % ≤ 1,50
1)
3,0 % 15,0 %
TPZ 1,0 % ± 180 min
± 18 min
ε ≤ 10 %
(only I∼)
≤ 1,50
1)
6,0 % 20,0 %
PX IEC 60044-1
BS: Class X
≤ 1,50
1)
3,0 % 10,0 %
C100
to
C800
ANSI ≤ 1,50
1)
5,0 % 15,0 %
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Siemens SIPROTEC 7SD610 Specifications

General

Brand	Siemens
Model	SIPROTEC 7SD610
Category	Relays
Language	English