Siemens 7SR242 Duobias - Page 16

7SR242 Duobias Commissioning & Maintenance Guide
©2010 Siemens Protection Devices Limited Chapter 6 Page 16 of 57
2.1.1.2 Results for testing 87BD with 2 current sources
W1
CURRENT (X I
N
)
0.00 1.00 1.50 2.00 2.50
87BD INITIAL
SETTING
87BD
1ST BIAS
SLOPE SETTING
W2 Current (x I
n
)
0.10 0.10 0.1 1.11 1.66 2.21 2.76
0.20 0.20 0.2 1.22 1.83 2.44 3.06
0.30 0.30 0.3 1.35 2.03 2.71 3.38
0.40 0.40 0.4 1.5 2.25 3.0 3.75
0.50 0.50 0.5 1.67 2.5 3.33 4.17
0.50 0.60 0.5 1.86 2.79 3.71 4.64
0.50 0.70 0.5 2.08 3.12 4.15 5.19
Selected Settings Test Results
0.00 1.00 1.50 2.00 2.50
Phase A Pickup
Phase B Pickup
Phase C Pickup
2.1.1.3 Differential Highset 87HS
Differential Highset can be tested by single phase secondary current injection. 87HS settings will usually be
higher than the continuous thermal rating of the relay current inputs and equipment or test procedure should be
arranged in such a way that the short term thermal withstand of the relay current inputs is not exceeded during
testing. 50% of relay setting current can be injected into each of the 2 winding inputs simultaneously to achieve a
differential current level of 100% if test current is limited by test equipment capacity.
The settings used for Secondary Injection test purposes should be:
W1 ICT Multiplier 1x
W1 ICT Connection Yy0,0deg
W2 ICT Multiplier 1x
W2 ICT Connection Yy0,0deg
These settings ensure a 1:1 ratio between the injected current and the relay setting. Note that operation of the
element can be achieved at a lower level of current if a higher ICT multiplier setting is applied.
During testing the Operate current can be monitored on the relay in the Instruments menu.