Protection relay question. ABB inverse-time

[[email protected]]

ABB distribution protection unit 2000R defines
inverse-time characteristics not according IEEE
Std C37.112-1996. Still they call
their curve for example "IEEE Very Inverse". The
eqation is the same, but
the parameters don't match.

Parameters:
IEEE Std C37.112-1996: A=19.61, B=0.491, p=2

ABB 2000R: 2.855, B=0.0712, p=2

"Extremely inverse" parameters don't match either.

What is this ABB version of IEEE inverse-time?

O.B.

 

[Figaro]

| ABB distribution protection unit 2000R defines
| inverse-time characteristics not according IEEE
| Std C37.112-1996. Still they call
| their curve for example "IEEE Very Inverse". The
| eqation is the same, but
| the parameters don't match.
|
| Parameters:
| IEEE Std C37.112-1996: A=19.61, B=0.491, p=2
|
| ABB 2000R: 2.855, B=0.0712, p=2
|
| "Extremely inverse" parameters don't match either.
|
| What is this ABB version of IEEE inverse-time?
|
| O.B.
|

Best to get in touch with ABB, Allentown PA.

 

[stevenal]

ABB distribution protection unit 2000R defines
inverse-time characteristics not according IEEE
Std C37.112-1996. Still they call
their curve for example "IEEE Very Inverse". The
eqation is the same, but
the parameters don't match.

Parameters:
IEEE Std C37.112-1996: A=19.61, B=0.491, p=2

ABB 2000R: 2.855, B=0.0712, p=2

"Extremely inverse" parameters don't match either.

What is this ABB version of IEEE inverse-time?

O.B.

They don't use the same equations. The IEEE formula is multiplied directly
by the time dial, while the ABB formula multiples it by (14n-5)/9 where n is
the time dial. Note that the A and B parameters are off by the same
multiple. Curve shape is the same, it just varies with the time dial
differently.

Also note that C37.112 first gives the equations and parameters, then uses
them to define the center of the conformance band. I suspect you'll find the
ABB curves lie within this band. Both formulas were intended to emulate an
induction disk, something ABB should know about.

 

[[email protected]]

They don't use the same equations. The IEEE formula is multiplied directly
by the time dial, while the ABB formula multiples it by (14n-5)/9 where n is
the time dial. Note that the A and B parameters are off by the same
multiple. Curve shape is the same, it just varies with the time dial
differently.

Also note that C37.112 first gives the equations and parameters, then uses
them to define the center of the conformance band. I suspect you'll find the
ABB curves lie within this band. Both formulas were intended to emulate an
induction disk, something ABB should know about.

Indeed, the ratio A/B is about the same for both
parameter sets. Thank you for a good answer.