I'd like to ask if anyone knows how to form an equation shown in the attached figure (from US4559491 patent).
In the image there is an expression for a phase R current at a point A for a phase-to-phase fault:
IR = (a^2 * I1R + a * I2R + a^2 * Ipre-fault) * a (1)
I can't figure out why (1) is so complicated because in general case phase R current is constructed from symmetrical components as:
IR = I1R + I2R + I0R (2)
For S and T phases there would be also one "a" and one "a^2" operator. Removing zero sequence component and adding a pre-fault phase current I get:
IR = I1R + I2R + Ipre-fault (3)
This is clearly not the same as (1). Am I missing something?
Thank you
In the image there is an expression for a phase R current at a point A for a phase-to-phase fault:
IR = (a^2 * I1R + a * I2R + a^2 * Ipre-fault) * a (1)
I can't figure out why (1) is so complicated because in general case phase R current is constructed from symmetrical components as:
IR = I1R + I2R + I0R (2)
For S and T phases there would be also one "a" and one "a^2" operator. Removing zero sequence component and adding a pre-fault phase current I get:
IR = I1R + I2R + Ipre-fault (3)
This is clearly not the same as (1). Am I missing something?
Thank you