2. APPLICATION
GEK-106243E
DTP Digital Transformer Protection
2-5
This value must not exceed 20% for any set of CTs. If it does, it will be necessary to choose a higher CT ratio and
repeat the calculations for selecting the relay tap, mismatch error, and CT ratio error. Please refer to the example
shown in section 2.3. TRANSFORMER CALCULATIONS
2.2.4 PERCENTAGE RESTRAINT SETTING
The appropriate percentage restraint K
1
is determined by the sum of:
•
The maximum range of the tap changer, in percent.
•
The maximum mismatch error of the relay taps, in percent.
In general, if the total error does not exceed 20% use a restraint of 25%. Since the DTP relay’s percentage
restraint can be adjusted in steps of 0.1%, a very precise setting can be selected.
The second characteristic K
2
available in the relay must be set according to the maximum through current during
external faults, where there might be partial or total CT saturation.
Summary of Contents for DTP-B
Page 23: ...3 OPERATING PRINCIPLES 3 6 DTP B Digital Transformer Protection GEK 106243E ...
Page 53: ...10 INSTALLATION AND MAINTENANCE 10 2 DTP B Digital Transformer Protection GEK 106243E ...
Page 68: ...12 FIGURES GEK 106243E DTP Digital Transformer Protection 12 3 Figure 3 RS 232 Connection ...
Page 69: ...12 FIGURES 12 4 DTP B Digital Transformer Protection GEK 106243E Figure 4 Dimensions Diagram ...
Page 70: ...12 FIGURES GEK 106243E DTP Digital Transformer Protection 12 5 Figure 5 Front View ...