Manual 37138C
ESDR 4T - Current Differential Protection Relay
© Woodward
Page 11/46
Measuring Inputs
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WARNING
Before detaching the secondary current transformer connections or those on the unit, you should en-
sure that the current transformer secondary is short-circuited.
NOTE
One side of the secondary of all CTs must be earthed. The earth connection should be made on the
side of the secondary facing the protected object. The polarity of the CTs must be in accordance with
the following diagram.
Star point
Transducer set 1
(high voltage side)
Block connection
Transducer set 2
(low voltage side)
Differential
current
monitoring
Transducer
set 1
Differential
current
monitoring
Transducer
set 2
L2
L1
L3
G
l (s2)
k (s1)
L2
l (s2)
k (s1)
l (s2)
k (s1)
l (s2)
k (s1)
L3
L2
L1
l (s2)
k (s1)
l (s2)
k (s1)
25
26
30
29
28
27
35
36
33
34
31
32
L1
L3
Generator diff. prot.
G
Protection object
Figure 3-3: CT (transducer) inputs
Terminal Measurement Description
A
max
25
Measured current L1, Transducer input s2 (l)
4 mm²
26
Measured current L2, Transducer input s1 (k)
4 mm²
27
Measured current L2, Transducer input s2 (l)
4 mm²
28
Measured current L2, Transducer input s1 (k)
4 mm²
29
Measured current L3, Transducer input s2 (l)
4 mm²
30
CT set 1
../1 A
or
../5 A
Measured current L3, Transducer input s1 (k)
4 mm²
31
Measured current L1, Transducer input s2 (l)
4 mm²
32
Measured current L1, Transducer input s1 (k)
4 mm²
33
Measured current L2, Transducer input s2 (l)
4 mm²
34
Measured current L2, Transducer input s1 (k)
4 mm²
35
Measured current L3, Transducer input s2 (l)
4 mm²
36
CT set 2
../1 A
or
../5 A
Measured current L3, Transducer input s1 (k)
4 mm²
