Choose Blocks to Model Cables or Lines

Step 2 of 2 in Model Cables and Lines in Simscape

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This tutorial shows how to select a block that models a cable or line using a mathematical model with the right level of complexity to meet your simulation goals.

If you chose a mathematical model in the previous tutorial, use the tables below to find a block that represents your conductor arrangement and uses the model you chose. Other factors, like how you want to parameterize the block and whether the block supports fault modeling, can also impact your block choice. In this tutorial, you learn about these differences between blocks and how to select a block for a range of DC and AC applications.

If you do not yet know what mathematical model you need, use the tables below to select a block based on your application or see Choose Mathematical Models that Represent Cables or Lines for more information about the different types of model that Simscape™ Electrical™ supports.

DC Applications

These tables show the blocks that you can use to represent DC cables using different mathematical models. Use these tables to select a block to model your cable. For steady-state DC applications where there is constant voltage and current, and no wave propagation, reflections, skin effect, or dielectric losses, a lumped-parameter model is often sufficient. A lumped-parameter model with series RL only is often sufficient for short cables or lines. A distributed parameter model is necessary only if the line is very long or you need accurate modeling of transient responses.

Lumped-Parameter Models with Series RL Only

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
Series Resistor and Inductor	A single conductor	Models resistance and inductance	Resistance and inductance	Resistor — Instantaneous transition to a faulted resistance value Inductor — Open-circuit fault between two inductor segments or a short-circuit fault in one of the segments	Steady-state or slow transient analysis of short DC cables: Battery cables in automotive applications Short DC busbars in power electronics Short harnesses in robotics or aerospace
Cable and Connectors	One or more conductors in a single cable Optionally, you can include the input and output connectors	Models resistance for each conductor Optionally models inductance for each conductor Models the connectors as contact resistances and inter-pin conductances	Conductors — Material and geometry You can specify the gauge as a diameter or using the American wire gauge (AWG) system. Connectors — Contact resistance and conductance between pins	Open-circuit faults in cables Short-circuit faults in cable connectors For an example that shows how to model and prevent a short-circuit fault in the connectors of an electric vehicle charging cable, see Model Short-Circuit Fault in EV Charging Cable.

Lumped Parameter Models with Pi- or L-Sections

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
Create your own model using these blocks: Resistor Inductor Capacitor	Custom	Models resistance, inductance, capacitance, and leakage conductance Includes distance effects, if you have repeating sections	Resistance, inductance, and capacitance	Resistor — Instantaneous transition to a faulted resistance value Inductor — Open-circuit fault between two inductor segments or a short-circuit fault in one of the segments Capacitor — Transition to faulted capacitance, series resistance, and parallel conductance values	Non-steady-state analysis of switching, startup, or fault events in medium-length DC cables, such as in: Solar PV arrays Battery energy storage systems (BESS) DC microgrids Railway traction systems Thermal modeling Modeling cables or lines with custom conductor arrangements

Distributed Frequency-Dependent Models

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
DC Cable	A single or double cable The cable cross section has six concentric layers: core conductor, insulation, sheath, inner jacket, armor, and serving.	Models resistance, inductance, capacitance, and leakage conductance as evenly distributed and frequency dependent	Material electrical parameters and geometric dimensions	Not supported	Simulating transient responses with high accuracy, over long distances, such as in: High-voltage direct-current (HVDC) transmission systems For an HVDC application example, see Model High-Voltage Direct-Current Transmission Using Modular Multilevel Converters. Underground and submarine applications

AC Applications

These tables show the blocks that you can use to represent cables or lines in AC applications using different mathematical models. Use these tables to select the right block to model your cable or line.

Delay-Based Models

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
Transmission Line Set the Model Type parameter to Delay-based and lossless or Delay-based and lossy.	Single-phase transmission line with an inner conductor and external shielding conductor	Represents the effects of inductance and capacitance as a time delay, without modeling energy storage explicitly Optionally incorporates series resistors to model signal losses	Transmission delay and characteristic impedance If signal loss is included: resistance per unit length, length, and the number of segments	Not supported	Simplified timing analysis of high-speed digital systems where the line delay dominates, such as in: Digital signal processing Control systems Synchronization in real-time systems

Lumped Parameter Models with Series RL Only

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
Series Resistor and Inductor	A single conductor	Models resistance and inductance	Resistance and inductance	Resistor — Instantaneous transition to a faulted resistance value Inductor — Open-circuit fault between two inductor segments or a short-circuit fault in one of the segments	Analysis of signal loss and delay in short AC cables at low frequencies: Short motor leads in industrial drives Low-frequency analog signal paths
Cable and Connectors	One or more conductors in a single cable Optionally, you can include the input and output connectors	Models resistance for each conductor Optionally models inductance that depends on the rated frequency Models the connectors as contact resistances and inter-pin conductances	Conductors — Material and geometry You can specify the gauge as a diameter or using the American wire gauge (AWG) system. Connectors — Contact resistance and conductance between pins	Open-circuit faults in cables Short-circuit faults in cable connectors

Lumped Parameter Models with Pi- or L-Sections

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
Create your own model using these blocks: Resistor Inductor Capacitor RLC (Three-Phase)	Custom	Models resistance, inductance, capacitance, and leakage conductance	Resistance, inductance, and capacitance	Resistor — Instantaneous transition to a faulted resistance value Inductor — Open-circuit fault between two inductor segments or a short-circuit fault in one of the segments Capacitor — Transition to faulted capacitance, series resistance, and parallel conductance values RLC (Three-Phase) — Instantaneous transition to a faulted resistance value for the impedance components You can choose a phase, two phases, or all three phases for the fault.	Analysis of medium-length AC cables carrying moderate frequency signals, such as: Motor cables Connections between converters, filters, and loads Simplified modeling of short lines at high frequency For a simple model of a lossless transmission line, see LC Transmission Line and Test Bridge. Thermal modeling Modeling cables or lines with custom conductor arrangements
AC Cable (Three-Phase)	A three-phase cable Each phase comprises a central conductor surrounded by a metallic sheath. The arrangement also includes the return path. You can choose different bonding configurations: Unbonded Single-point bonded Double-point bonded Cross-bonded For an example that allows you to choose the number of segments and type of bonding, see AC Cable with Bonded Sheaths.	Models the resistance of each phase and sheath and the return path Models the inductance and mutual inductance between each phase, sheath, and the return path Models the capacitance between each phase and the sheath of that phase, and between each sheath and the return path Assumes the phases are equivalent for resistance calculations Assumes that relative to the phase-to-sheath capacitance and the sheath-return capacitances, all other capacitances are negligible due to the shielding provided by the conducting sheaths Models capacitive coupling between the lines Includes distance effects, if you have repeating sections	Physical material properties and geometry	Not supported	Simplified system-level modeling of three-phase cables in power transmission applications
Transmission Line Set Model Type to Lumped parameter L-section or Lumped parameter pi-section.	Single-phase transmission line with an inner conductor and external shielding conductor	Models the line as pi- or L-sections Models capacitive coupling between the lines Includes distance effects, if you have repeating sections	Characteristic impedance or inductance per unit length Resistance, capacitance, and insulation conductance per unit length Reference Frequency Line length and number of segments	Not supported	Simplified system-level modeling of lines in power transmission applications For a simplified model of a power grid, with three-phase lines, see IEEE 9-Bus System.
Transmission Line (Three-Phase)	A three-phase transmission line with ground connections at each end of the line	Models the line as pi-sections: includes phase resistance, phase self-inductance, line-line mutual inductance and resistance, line-line capacitance, and line-ground capacitance Models capacitive coupling between the lines Includes distance effects, if you have repeating sections	Length, resistance, mutual resistance, self and mutual inductance, and capacitance Reference Frequency	Single-phase-to-ground Two-phase Two-phase-to-ground. Three-phase Three-phase-to-ground You define the fault location using an input physical signal.

Lumped-Parameter Models with Magnetically-Coupled Lines

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
Coupled Lines (Pair)	Two magnetically-coupled lines	Models the series resistance, self-inductance, and parallel conductance for each line Models mutual resistance, mutual inductance and magnetic-coupling between the lines The mutual resistance can model common return path losses.	Self-inductance, series resistance, and parallel conductance of each line Mutual resistance and mutual inductance between the lines	Not supported	Modeling lines when magnetic coupling is significant Magnetic coupling is most prominent when: The lines are parallel and close together The self-inductances of the lines are high The AC frequency of the network is high
Coupled Lines (Three-Phase)	Three magnetically-coupled lines	Models the series resistance, self-inductance, and parallel conductance for each line Models mutual resistance, mutual inductance, and magnetic-coupling between the lines The mutual resistance can model common return path losses.	Self-inductance, series resistance, and parallel conductance of each line Mutual resistance and mutual inductance between the lines	Single-phase-to-ground, two-phase, and three-phase faults

Distributed Frequency-Independent Models

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
Transmission Line Set Model Type to Distributed parameter line.	Single-phase transmission line with an inner conductor and external shielding conductor	Models the line using a distributed model that includes distance effects Uses the telegrapher's equations for electromagnetic behavior Models the line with high accuracy at a given frequency but the accuracy drops outside the frequency point specified from the block mask	Resistance, inductance, capacitance, and insulation conductance per unit length Reference Frequency Line length	Not supported	Long-distance, low-frequency power lines Impedance matching and reflection analysis

Distributed Frequency-Dependent Models

Block	Conductor Arrangement	Physics	Parameterization	Fault Modeling	Applications
Frequency-Dependent Overhead Line (Three-Phase)	A three-phase line	Models the line using a distributed, frequency-dependent model that includes distance and frequency effects Uses the telegrapher's equations for electromagnetic behavior Includes mutual coupling to represent zero sequence impedance Employs rational fitting and vector fitting for phase domain modeling Computes frequency-dependent impedance and admittance matrices The calculations also depend on the loss, inductance, and capacitance of the return path.	Data from cable geometry and arrangement	Not supported	Long-distance AC transmission lines with ground return, where behavior is highly frequency dependent Engineering applications where detailed electromagnetic behavior is required: Circuit board operation PWM inverter-fed motors Long cable runs with switching surges Simulating accurate transient responses over a wide range of conditions: Frequency — 0.01 Hz to 100 kHz Line length — 1 m to 300 km