The Simulation of a Test GCB’s

Coupled Electromagnetic-Mechanic Analysis

Coupled Electromagnetic-Mechanic Dynamic

Analysis of Generator Circuit Breakers

Abstract: Due to their specific position and role in electric power systems, generator circuit breakers (GCBs) must be so developed and manufactured that they can

withstand extremely high short circuit currents several times over their entire lifetime. Therefore, an accurate and efficient method for performing a coupled

electromagnetic-mechanical simulation of a GCB in its full geometrical complexity is of paramount importance for daily design. The suggested method is fast,

accurate, efficient, robust, and suitable for 3-D geometries of high complexity.

Jasmin Smajic, Cornelius Jäger

University of Applied Sciences of Eastern Switzerland (HSR)

Severin Neubauer, Astrid Bauer, Daniel Jun Chen, M. Widenhorn

ABB Switzerland Ltd.

HSRHOCHSCHULE FÜR TECHNIK

RA PPERSW IL

FHO Fachhochschule Ost schw ei zUNIVERSITY OF APPLIED SCIENCES OF EASTERN SWITZERLAND

Problem Statement

Simulation Results and their Verification

These GCB’s are designed to withstand a

non-harmonic short circuit current with a

peak value up to 685 kA. The occurring,

corresponding magnetic force acting on

the GCB is also extremely high, which

makes the mechanical design very

demanding. To avoid oversizing and high

material cost, an efficient electro-

magnetic-mechanic simulation method is

needed.

The assumptions of the analysis: 1) Displacements of the GCB structure due to the magnetic

forces do not influence the magnetic field and force distribution (i.e. weak or single directional

electromagnetic-mechanical coupling is sufficient). 2) Induced eddy currents do not influence

significantly the distribution of short circuit forces (i.e. static current distribution is sufficient).

3) No magnetic bodies are present in the model and the model is linear (i.e. material properties

do not depend on field values).

The verification of the method was an important task to prove its accuracy.

Therefore a simple test subject was created and a measurement setup was build.

The results of measurements on the Π-shaped subject confirmed the obtained

simulation results.

INSTITUTE OF ENERGY

TECHNOLOGY

Stationary current distribution: Biot-Savart integration:

Stationary magnetic force density:

Transient mechanical analysis based on

the dynamic equilibrium equation:

Comparison of the simulated and measured

results. The mechanical model is ideal (no

damping).

Comparison of the simulated and measured

results. Mechanical model has the beta-damping

or structural damping coefficient of 0.001.

The measurement arrangement: copper conductor, capacitor,

shunt, oscilloscope, short circuit switch and high speed camera.

Ansys model of the conductor, measured short

circuit current and the simulation results in Ansys.

Definition of the short-circuit current:

𝐼𝑅𝑀𝑆 = 63 𝑘𝐴 , 𝑓 = 50 𝐻𝑧 , 𝜏 = 133 𝑚𝑠

𝑖𝑅 𝑡 = 2 ∙ 𝐼𝑅𝑀𝑆 ∙ sin 𝜔𝑡 −𝜋

2+𝑒−

𝑡𝜏

0 0.02 0.04 0.06 0.080

0.5

1

1.5

2

2.5

3

3.5

4

Time (s)

Vo

n M

ise

s S

tre

ss (

MP

a)

Generated FEM-mesh of the GCB

(approximately 1 Mio nodes).

Von Mises stress distribution (Aluminium)

Path of the short circuit current in

the GCB.

FEM vs. BEM-Results, Simulation of a GCB HECS-130R

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.080

0.5

1

1.5

2

2.5

3

3.5

4

Time (sec)

Magnitude o

f th

e d

ispla

cem

ent

(mm

)

Displacement vs. Time recorded at: (-0.16396,0.76424,0.74716)m

POLOPT+ABAQUS - 27mm

ANSYS - 30mmThe extension of the method to

three-phase is straightforward.

The comparison of the results of

the previously developed

simulation chain based on BEM

(electromagnetic part) and Abaqus

(mechanical part) and the

suggested FEM approach has

revealed an acceptable accuracy.