SOURC36
Current Source
SOURC36 Element Description
SOURC36 is a primitive (consisting of predefined geometries) used to supply current source data to magnetic field problems. The element represents a distribution of current in a model employing a scalar potential formulation (degree of freedom MAG). The currents are used to calculate a source magnetic field intensity (Hs) using a numerical integration technique involving the Biot-Savart law. The Hs term is used in the formulation as a magnetic load on the model. See SOURC36 in the Mechanical APDL Theory Reference for more details about this element.
SOURC36 Input Data
The geometry, node locations, and the coordinate system for this element are shown in Figure 36.1: SOURC36 Geometry. The element input data includes three nodes and the following real constants (see "SOURC36 Input Summary"):
- TYPE
Source type - use 1 for Coil, 2 for Bar, 3 for Arc.
- CUR
Total current flowing through source (that is, number of turns times current per turn).
- DY
Characteristic y dimension for source type.
- DZ
Characteristic z dimension for source type.
- EPS
Convergence criterion for source field (Hs) calculations for arc and coils. Defaults to 0.001. EPS represents the relative maximum difference in the field Hs calculated at any node during the iterative calculation of the source field. EPS does not apply for bar sources.
Characteristic dimensions described above are in the element coordinate system. In the case of circular sources (coils, arcs) the radius is determined from the first and third nodes (I, K). For bar sources, the length is determined from the first two nodes (I, J).
As a modeling aid, a magnetic command macro, RACE, is available within the Mechanical APDL command set. This macro enables you to build a racetrack conductor from SOURC36 primitives. The macro is discussed in further detail in the Command Reference and in the Low-Frequency Electromagnetic Analysis Guide.
A summary of the element input is given in "SOURC36 Input Summary". A general description of element input is given in Element Input.
SOURC36 Input Summary
- Nodes
I, J, K (nodes I, J and K define the characteristic length, current flow direction, and orient the source)
- Degrees of Freedom
None
- Real Constants
TYPE, CUR, DY, DZ, (Blank), (Blank), (Blank), (Blank), EPS See Table 36.1: SOURC36 Real Constants for a description of the real constants. - Material Properties
None
- Surface Loads
None
- Body Loads
None
- Special Features
None
- KEYOPTS
None
Table 36.1: SOURC36 Real Constants
| No. | Name | Description |
|---|---|---|
| 1 | TYPE | Source type |
| 2 | CUR | Total current through source |
| 3 | DY | Characteristic Y dimension |
| 4 | DZ | Characteristic Z dimension |
| 5 ... 8 | (Blank) | |
| 9 | EPS | Convergence criteria for Hs calculations |
As a modeling aid, a magnetic command macro, RACE, is available within the Mechanical APDL command set. This macro enables you to build a racetrack conductor from SOURC36 primitives. The macro is discussed in further detail in the Command Reference and in the Low-Frequency Electromagnetic Analysis Guide.
SOURC36 Output Data
The source element has no output of its own since it is used only to supply current source data to magnetic field problems.
SOURC36 Assumptions and Restrictions
The source element must have characteristic DY or DZ values that are greater than zero.
The third node must not be colinear with the first two nodes.
The nodes for this element need not be attached to any other elements.
For the coil and the arc (types 1 and 3), the K-I line determines the radius (and the x axis) and the J node orients the x-y plane.
For the arc (type 3) the subtended angle must be less than 180°. When you specify an arc using three points, Mechanical APDL always uses the angle that is less than 180°.
All source element nodes should be located a least 1E-6 units apart.
Source element cannot have a zero inside radius (Radius ≠ DY/2 for types 1 and 3).
The EPS convergence criterion is a measure of the relative difference in the calculated Hs field used during an iterative numerical integration procedure for coil and arc source primitives. The default value (.001) provides for good accuracy in regions outside of the source primitive location. For highly accurate calculations within the source primitive domain, the criteria may have to be tightened (that is, a factor of 20 increase would be represented by EPS = .00005).
Tightening the convergence criteria will significantly increase the solution run time.
Users concerned with accurate calculations within the coil and arc source primitive domain should experiment with the criteria until satisfied with the degree of accuracy obtained.
All currents for a magnetostatic model employing the scalar potential formulation must be specified. Whereas symmetry conditions on the finite element model may be employed, no symmetry may be employed on the current source elements.