CIRCU124

Electric Circuit

CIRCU124 Element Description

CIRCU124 is a general circuit element applicable to circuit simulation. The element has up to 6 nodes to define the circuit component and one or two degrees of freedom per node to model the circuit response.

CIRCU124 can be directly coupled to the electromagnetic or stranded coil analysis options of PLANE233, SOLID236, and SOLID237 through the VOLT degree of freedom.

For electric circuit applications (KEYOPT(3) = 0), CIRCU124 is applicable to static, harmonic, and transient analyses. For acoustic equivalent circuit applications (KEYOPT(3) = 1), CIRCU124 is applicable to harmonic and transient analyses.

CIRCU124 Input Data

The geometry, node definition, and degree of freedom options are shown in Figure 124.1: CIRCU124 Circuit Element Options (circuit components) and Figure 124.2: CIRCU124 Circuit Source Options (circuit source options). The element is defined by active and passive circuit nodes. Active nodes are those connected to an overall electric circuit, and passive nodes are those used internally by the element and not connected to the circuit.

Element circuit components and sources are defined by KEYOPT(1) settings and its corresponding real constants. Real constant input is dependent on the element circuit option used. A summary of the element input options is given in "CIRCU124 Input Summary". Real constants numbers 15 and 16 are created by the GUI Circuit Builder (see the Modeling and Meshing Guide), and are not required input for analysis purposes. The element is characterized by these degrees of freedom:

VOLT (voltage) - KEYOPT(3) = 0
CURR (current)

Figure 124.1: CIRCU124 Circuit Element Options

Figure 124.2: CIRCU124 Circuit Source Options

Independent voltage and current sources (KEYOPT(1) = 3 or 4) may be excited by AC/DC, sinusoidal, pulse, exponential, or piecewise linear load functions as defined by KEYOPT(2); see Figure 124.3: Load Functions and Corresponding Real Constants for Independent Current and Voltage Sources.

The time-step size for a transient analysis is controlled by the DELTIM or NSUBST commands. The CIRCU124 element does not respond to automatic time stepping (AUTOTS command), but AUTOTS can be used as a mechanism for ramping the time step to its final value. For coupled electromagnetic-circuit problems, automatic time stepping may be used if controls are placed on degrees of freedom other than VOLT or CURR, or loads associated with those degrees of freedom.

For problems using the CIRCU124 element, the sparse direct solver is chosen by default.

CIRCU124 Input Summary

Nodes

I, J, K, L, M, N

Degrees of Freedom

VOLT, CURR (see Figure 124.1: CIRCU124 Circuit Element Options), PRES

Real Constants

R, L, C, I, V, (blank), (blank), K, G, E, H, F

Dependent on KEYOPT(1) and KEYOPT(2) settings. See Table 124.1: CIRCU124 Real Constants for details.

In a full harmonic analysis (ANTYPE,HARMIC and HROPT,FULL), real constants R, L, and C can be defined as table parameters using the frequency as the primary variable (Var1 = FREQ on the *DIM command).

In a full transient analysis (ANTYPE,TRANS and TRNOPT,FULL), real constants R, L, and C can be defined as table parameters using time as the primary variable (Var1 = TIME on the *DIM command).

Material Properties

None

Surface Loads

None

Body Loads

See KEYOPT(2)

Special Features

None

KEYOPT(1)

Circuit component type:

0 --: Resistor
1 --: Inductor
2 --: Capacitor
3 --: Independent Current Source
4 --: Independent Voltage Source
8 --: Mutual Inductor
9 --: Voltage-Controlled Current Source
10 --: Voltage-Controlled Voltage Source
11 --: Current-Controlled Voltage Source
12 --: Current-Controlled Current Source

KEYOPT(2)

Body loads available if KEYOPT(1) = 3 or 4:

0 --: DC or AC Harmonic load
1 --: Sinusoidal load
2 --: Pulse load
3 --: Exponential load
4 --: Piecewise Linear load

KEYOPT(3)

Circuit type:

0 --: Electrical circuit with the VOLT degree of freedom

Table 124.1: CIRCU124 Real Constants

Circuit Option and Graphics Label

KEYOPT(1)

Real Constants

Resistor (R)

R1 = Resistance (RES)

Inductor (L)

R1 = Inductance (IND)

R2 = Initial inductor current (ILO)

Capacitor (C)

R1 = Capacitance (CAP)

R2 = Initial Capacitor Voltage (VCO)

Mutual Inductor (K)

R1 = Primary Inductance (IND1)

R2 = Secondary Inductance (IND2)

R3 = Coupling Coefficient (K)

Independent Current Source (I)

For KEYOPT(2) = 0:

R1 = Amplitude (AMPL)

R2 = Phase angle (PHAS)

For KEYOPT(2) > 0: see Figure 124.3: Load Functions and Corresponding Real Constants for Independent Current and Voltage Sources.

Voltage-Controlled Current Source (G)

R1 = Transconductance (GT)

Current-Controlled Current Source (F)

R1 = Current Gain (AI)

Independent Voltage Source (V)

For KEYOPT(2) = 0:

R1 = Amplitude (AMPL)

R2 = Phase angle (PHAS)

For KEYOPT(2) > 0: see Figure 124.3: Load Functions and Corresponding Real Constants for Independent Current and Voltage Sources.

Voltage-Controlled Voltage Source (E)

R1 = Voltage Gain (AV)

Current-Controlled Voltage Source (H)

R1 = Transresistance (RT)

Note: For all above Circuit options, the GOFFST and ID real constants (numbers 15 and 16) are created by the Circuit Builder automatically:

Figure 124.3: Load Functions and Corresponding Real Constants for Independent Current and Voltage Sources

CIRCU124 Output Data

The element output for this element is dependent on the circuit option selected. Table 124.2: CIRCU124 Element Output Definitions summarizes the element output data.

The Element Output Definitions table uses the following notation:

A colon (:) in the Name column indicates that the item can be accessed by the Component Name method (ETABLE, ESOL). The O column indicates the availability of the items in the file jobname.out. The R column indicates the availability of the items in the results file.

In either the O or R columns, “Y” indicates that the item is always available, a letter or number refers to a table footnote that describes when the item is conditionally available, and “-” indicates that the item is not available.

Table 124.2: CIRCU124 Element Output Definitions

Name	Definition	O	R
For KEYOPT(1) = 0: Resistor
EL	Element Number	Y	Y
NODES	Nodes - I, J	Y	Y
RES	Resistance	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current	Y	Y
POWER	Power loss	Y	Y
For KEYOPT(1) = 1: Inductor
EL	Element Number	Y	Y
NODES	Nodes - I, J	Y	Y
IND	Inductance	Y	Y
IL0	Initial current	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current	Y	Y
POWER	Power absorption	Y	Y
For KEYOPT(1) = 2: Capacitor
EL	Element Number	Y	Y
NODES	Nodes - I, J	Y	Y
CAP	Capacitance	Y	Y
VC0	Initial voltage	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current	Y	Y
POWER	Power absorption	Y	Y
For KEYOPT(1) = 3: Independent Current Source
EL	Element Number	Y	Y
NODES	Nodes - I, J	Y	Y
CURRENT SOURCE	Real or imaginary component of applied current	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current	Y	Y
POWER	Power (loss if positive, output if negative)	Y	Y
For KEYOPT(1) = 4: Independent Voltage Source
EL	Element Number	Y	Y
NODES	Nodes - I, J, K	Y	Y
VOLTAGE SOURCE	Real or imaginary component of applied voltage	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current at node K	Y	Y
POWER	Power (loss if positive, output if negative)	Y	Y
For KEYOPT(1) = 8: 3D Mutual Inductor (Transformer)
EL	Element Number	Y	Y
NODES	Nodes - I, J, K, L	Y	Y
IND1	Primary inductance	Y	Y
IND2	Secondary inductance	Y	Y
INDM	Mutual inductance	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current in I-J branch	Y	Y
CONTROL VOLT	Voltage drop between node K and node L	Y	Y
CONTROL CURR	Current in K-L branch	Y	Y
POWER	Power absorption	Y	Y
For KEYOPT(1) = 9: Voltage Controlled Current Source
EL	Element Number	Y	Y
NODES	Nodes - I, J, K, L	Y	Y
GT	Transconductance	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current in I-J branch	Y	Y
CONTROL VOLT	Voltage drop between node K and node L	Y	Y
POWER	Power (loss if positive, output if negative)	Y	Y
For KEYOPT(1) = 10: Voltage Controlled Voltage Source
EL	Element Number	Y	Y
NODES	Nodes - I, J, K, L, M	Y	Y
AV	Voltage gain	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current at node K	Y	Y
CONTROL VOLT	Voltage drop between node L and node M	Y	Y
POWER	Power (loss if positive, output if negative)	Y	Y
For KEYOPT(1) = 11: Current Controlled Voltage Source
EL	Element Number	Y	Y
NODES	Nodes - I, J, K, L, M, N	Y	Y
GT	Transresistance	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current at node K	Y	Y
CONTROL VOLT	Voltage drop between node L and node M	Y	Y
CONTROL CURR	Current at node N	Y	Y
POWER	Power (loss if positive, output if negative)	Y	Y
For KEYOPT(1) = 12: Current Controlled Current Source
EL	Element Number	Y	Y
NODES	Nodes - I, J, K, L, M, N	Y	Y
AI	Current gain	Y	Y
VOLTAGE	Voltage drop between node I and node J	Y	Y
CURRENT	Current at node K	Y	Y
CONTROL VOLT	Voltage drop between node L and node M	Y	Y
CONTROL CURR	Current at node N	Y	Y
POWER	Power (loss if positive, output if negative)	Y	Y

Table 124.3: CIRCU124 Item and Sequence Numbers lists output available through the ETABLE command using the Sequence Number method. See The General Postprocessor (POST1) in the Basic Analysis Guide and The Item and Sequence Number Table in this reference for more information. The following notation is used in Table 124.3: CIRCU124 Item and Sequence Numbers:

Name: output quantity as defined in the Table 124.2: CIRCU124 Element Output Definitions
Item: predetermined Item label for ETABLE command
E: sequence number for single-valued or constant element data

Table 124.3: CIRCU124 Item and Sequence Numbers

Output Quantity Name	ETABLE and ESOL Command Input
Output Quantity Name	Item	E
VOLTAGE	SMISC	1
CURRENT	SMISC	2
CONTROL VOLT	SMISC	3
CONTROL CURR	SMISC	4
POWER	NMISC	1
SOURCE (real)	NMISC	2
SOURCE (imaginary)	NMISC	3

CIRCU124 Assumptions and Restrictions

For static analyses, a capacitor circuit element is treated as an open-circuit and an inductor circuit element is treated as a short-circuit.
Only MKS units are allowed (EMUNIT command).
The resistor, inductor, capacitor, independent current source, and mutual inductor circuit options produce symmetric coefficient matrices while the remaining options produce unsymmetric matrices.
The sparse solver is the default for problems using the CIRCU124 element. Even if you choose a different solver, Mechanical APDL switches to the sparse solver when CIRCU124 elements are present.
This element may not be compatible with other elements with the VOLT degree of freedom. To be compatible, the elements must have the same reaction force (see Element Compatibility in the Low-Frequency Electromagnetic Analysis Guide).

CIRCU124 Product Restrictions

There are no product-specific restrictions for this element.