Loading (LD)

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Loading (LD)

Purpose: To specify the impedance loading on one segment or a number of segments. Series and parallel RLC circuits can be generated. In addition, a finite conductivity can be specified for segments.

Card:

         _________________________________________________________________
        /2|  5|   10|   15|   20|    30|    40|    50|    60|    70|    80|
       /  |   |     |     |     |      |      |      |      |      |      |
      |   |   |     |     |     |      |      |      |      |      |      |
      |LD |I1 | I2  | I3  | I4  |  F1  |  F2  |  F3  |  F4  |  F5  |  F6  |
      |   |   |     |     |     |      |      |      |      |      |      |
      |   | L |  L  |  L  | L   | ZLR  | ZLI  | ZLI  |  B   |  B   |  B   |
      |   | D |  D  |  D  | D   |      |      |      |  L   |  L   |  L   |
      |   | T |  T  |  T  | T   |      |      |      |  A   |  A   |  A   |
      |   | Y |  A  |  A  | A   |      |      |      |  N   |  N   |  N   |
      |   | P |  G  |  G  | G   |      |      |      |  K   |  K   |  K   |
      |   |   |     |  F  | T   |      |      |      |      |      |      |
      |  The numbers along the top refer to the last column in each field |
      |   |   |     |     |     |      |      |      |      |      |      |

Parameters:

Integers

LDTYP (I1) - Determines the type of loading which is used. The options are:
  -1 - short all loads (used to nullify previous loads). The remainder of the card is left blank.
  0 - series RLC, input ohms, henries, farads.
  1 - parallel RLC, input ohms, henries, farads.
  2 - series RLC, input ohms/meter, henries/meter, farads/meter.
  3 - parallel RLC, input ohms/meter, henries/meter, farads/meter.
  4 - impedance, input resistance and reactance in ohms.
  5 - wire conductivity, mhos/meter.

LDTAG (I2) Tag number; identifies the wire section(s) to be loaded by its (their) tag numbers. The next two parameters can be used to further specify certain segment(s) on the wire section(s). Blank or zero here implies that absolute segment numbers are being used in the next two parameters to identify segments. If the next two paramters ara blank or zero, all segments with tag LDTAG are loaded.

LDTAGF (13) - Equal to m specifies the mth segment of the set of segments whose tag numbers equal the tag number specified in the previous parameter. If the previous parameter (LDTAG) is zero, LDTAGF then specifies an absolute segment number. If both LDTAG and LDTAGF are zero, all segments will be loaded.

LDTAGT (14) - Equal to n specifies the nth segment of the set of segments whose tag numbers equal the tag number specified in the parameter LDTAG. This parameter must be greater than or equal to the previous param- eter. The loading specified is applied to each of the mth through nth segments of the set of segments having tags equal to LDTAG. Again if LDTAG is zero, these parameters refer to absolute segment numbers. If LDTAGT is left blank, it is set equal to the previous parameter (LDTAGF).

Floating Point Input for the Various Load Types
  a. Series RLC (LDTYP = 0)
    ZLR (Fl) - Resistance in ohms, if none, leave blank.
    ZLI (F2) - Inductance in henries, if none, leave blank.
    ZLC (F3) - Capacitance in farads, if none, leave blank.
  b. Parallel RLC (LDTYP = 1), floating point input same as a.
  c. Series RLC (LDTYP = 2) input, parameters per unit length.
    ZLR - Resistance in ohms/meter, if none, leave blank.
    ZLI - Inductance in henries/meter, if none, leave blank.
    ZLC - Capacitance in farads/meter, if none, leave blank.
  d. Parallel RLCRLC (LDTYP = 3), input parameters per unit length, floating point input same as c.

  e. Impedance (LDTYP = 4)
    ZLR - Resistance in ohms.
    ZLI - Reactance in ohms.
  f. Wire conductivity (LDTYP = 5)
    ZLR - Conductivity in mhos/meter.

Notes:
- Loading cards can be input in groups to achieve a desired structure loading. The maximum number of loading cards in a group is determined by dimensions in the program. The limit is presently 30.
- If a segment is loaded more than once by a group of loading cards, the loads are assumed to be in series (impedances added), and a comment is printed in the output alerting the user to this fact.
- When resistance and reactance are input (LDTYP = 4), the impedance does not automatically scale with frequency.
- Loading cards used after any form of execute, require the regeneration of the structure matrix.
- Since loading modifies the interaction matrix, it will affect the conditions of plane or cylindrical symmetry of a structure. If a structure is geometrically symmetric and each symmetric section is to receive identical loading, then symmetry may be used in the solution. The program is set to utilize symmetry during geometry input by inputting the data for one symmetric section and completing the structure with a GR or GX card. If symmetry is used, the loading on only the first symmetric section is input on LD cards. The same loading will be assumed on the other sections. Loading should not be specified for segments beyond the first section when symmetry is used. If the sections are not identically loaded, then during geometry input the program must be set to a no-symmetry condition to permit independent loading of corresponding segments in different sections.

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