Second Harmonic Restraint Test - ISA T1000 PLUS User Manual

DOC. MIE91093
I
D
Therefore, applying current Iac only (from T1000 PLUS)

may result in a trip even when the current generated
by the D1000 is zero: you must increase D1000 current
until the relay contact drops out
If transformer Taps have to be taken into account, the

above formulas become a little more complex:
Restraint Current:
o

I
R
Differential Current:
o
I
D

1.15.8 Second harmonic restraint test

This test requires that you generate a distorted waveform:
1.5
1
0.5
0
0 0.005
-0.5
-1
-1.5
The only way to generate such current waveform is to parallel
the main and auxiliary currents, having selected an 100 Hz
Rev. 1.34
I I
  
A
I
B
3
I I

A
Tap
Tap 3
1
2
I I
 
A
Tap
Tap 3
1
0.01
50 Hz 2nd Harm
 
1
( I I )
1 2
3
I

B 1
Tap 3
2 
1
I
 
B 1
Tap 3
2
1
0.015
50 Hz + 2nd Harm
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
( I I )
1 2
Tap
2
2

( I I )
1 2
Tap
2
0.02 0.025