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Measure negative sequence currents.
- Thread starter Audun
- Start date
It is possible to configure passive elements (reactors and resistors) in such a way as to develop a voltage that is proportional to negative sequence current.
If you have a copy of the Westinghouse "Applied Protective Relaying", there is an example schematic shown in Figure 3-8. Older electro-mechanical 46 relays operated on this principle.
If you have a copy of the Westinghouse "Applied Protective Relaying", there is an example schematic shown in Figure 3-8. Older electro-mechanical 46 relays operated on this principle.
One possible “out-of-the-box” capability is a Basler BE1-46N with analog output option
The text, A R Van Warrington, "Protection Relays Their Theory and Practice"
The text, A R Van Warrington, "Protection Relays Their Theory and Practice"
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electricpete
Electrical
Well, there are plenty of negative sequence current meters (used on generators) and relays on the market. Some of the relays based on electromechanical.
HCB-1 pilot wire relay includes negative sequence filter. Manual is available here but very slow. I don't know if the diagram is in there:
HCB-1 pilot wire relay includes negative sequence filter. Manual is available here but very slow. I don't know if the diagram is in there:
electricpete
Electrical
Well, the hcb flyer finally loaded and nothing there.
I hate to try to think about reinventing the wheel since it's already been done. But... I'm just thinking about how you would do it starting from the definition.... something like I- = Ia + A*Ib + A^2*Ic where A is exp(j*120 degrees)... and you might switch the B and C coefficients depending upon your power system phase rotation.
So... how to shift the phase of a current. Well certainly putting it through an RC or RL network could develop that phase shift on the voltage... then how to add the voltages? Hmmm.
I hate to try to think about reinventing the wheel since it's already been done. But... I'm just thinking about how you would do it starting from the definition.... something like I- = Ia + A*Ib + A^2*Ic where A is exp(j*120 degrees)... and you might switch the B and C coefficients depending upon your power system phase rotation.
So... how to shift the phase of a current. Well certainly putting it through an RC or RL network could develop that phase shift on the voltage... then how to add the voltages? Hmmm.
jbartos
Electrical
- Jan 15, 2000
- 6,440
Suggestion: Reference:
1. C. Russell Mason "The Art and Science of Protective Relaying," John Wiley and Sons, Inc., 1956,
page 189 figure 22 A positive-phase-sequence-current filter and relay.
By interchanging the leads in which Ib and Ic flows, the filter becomes a negative-phase-sequence-current filter.
1. C. Russell Mason "The Art and Science of Protective Relaying," John Wiley and Sons, Inc., 1956,
page 189 figure 22 A positive-phase-sequence-current filter and relay.
By interchanging the leads in which Ib and Ic flows, the filter becomes a negative-phase-sequence-current filter.
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