Basler Electric BE1-11g - Manual (Page 125)

9424200994 Rev N 113
Figure 70. Phase Current Differential Element Logic Block
Table 39. Logic Inputs and Outputs
Name Function Purpose
Block Input Disables the 87 function when true
Trip Output True when the 87 element is in a trip condition
Pickup Output True when the 87 element is in a pickup condition
Unrestrained Trip Output True when the 87 element is in an unrestrained trip condition
2 nd Harmonic Inhibit Output True when the 87 is inhibited by 2 nd harmonic ratio
5 th Harmonic Inhibit Output True when the 87 is inhibited by 5 th harmonic ratio
Settings
Tap Compensation Settings
The measured currents must be tap adjusted to eliminate magnitude mismatch prior to being used by the
Phase Current Differential Protection (87) element. The tap adjust factors can be manually calculated per
Equation 13. Or, the user can enter the MVA and kV base parameters (Table 40) and the BE1-11g will
calculate the tap-adjust factors using CT Ratio (CTR) and Compensation Factor (COMP) parameters from
the current measurement input function settings. For a transformer application, the mismatch will be at a
minimum if the actual transformer voltage ratings are used.
𝑇𝐴𝑃𝑛 =
𝑀𝑉𝐴 × 1000 × 𝐶𝑂𝑀𝑃𝑛
√3 × 𝑘𝑉𝑛 × 𝐶𝑇𝑅𝑛
Equation 13. Calculate Tap Adjust Factors
Table 40. MVA and kVn Base Parameters
Parameter Description Explanation
Tapn Restraint winding The BE1-11g has 2 restraint windings (2 taps).
MVA MVA base Full load MVA or top rating of the protected equipment.
kVn kV base for CT input n L-L Voltage in kV for each CT input circuit.
CTRn CT ratio for CT input n Actual ratio not effective ratio.
COMPn
Phase compensation
adjustment factor for
CT input n
√3 if CTs are connected in Delta (CTcon = DAB or DAC).
1 in all other cases.
See the
Configuration chapter.
The input currents can be tap adjusted up to a spread ratio of 10:1. If the ratio between TAP1 and TAP2
is greater than ten, it will be necessary to adjust the CT ratios to bring the tap factors closer together.
When the auto-tap calculation feature is used, the BE1-11g will give an error message if the spread ratio
is greater than ten.
BE1-11g 0BPhase Current Differential (87) Protection