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Laminated Busbar Thermal Simulation – ANSYS Best Practices

07/10

2026

By A&JLINK Engineering Team · Last updated July 2026 · 8 min read
The short answer
How to predict busbar temperature with the ANSYS toolchain — and the two rules that separate good simulations from bad.
  • ✓Why simulate. Most busbar failures are thermal, and temperature is a field you cannot see or easily measure.
  • ✓What you are simulating. Joule heating as the source, conduction/convection/radiation as the sinks, contact resistance as the hard part.
  • ✓The two rules. Model copper as temperature-dependent, and treat bolted-joint contact resistance honestly — it is the largest source of error.
A laminated busbar is a low-inductance conductor, but it is also a thermal system. Current through it becomes heat, and that heat has to go somewhere — into the surrounding air, into the heatsinks at its ends, into the insulation that wraps it. When the heat does not leave fast enough, temperature climbs, insulation ages, and joints oxidize. Most busbar failures, in the end, are thermal failures.
This article is about how to predict that temperature with simulation — specifically with the ANSYS toolchain — before a single prototype is built. It is a methods article, not a physics review: for how temperature changes a busbar's electrical and mechanical behavior, see our companion piece on how temperature affects laminated busbar performance.
Scope: this article covers the workflow and best practices for thermal simulation of laminated busbars in ANSYS — the physics, the tool selection, the model setup, and the boundary conditions. It assumes the reader is an engineer who wants a reliable temperature prediction, not a marketing overview.
A laminated busbar is the backbone of low-inductance power distribution, and simulating its temperature is how you keep that backbone from quietly degrading.

1. Why Simulate Busbar Temperature

The reason to simulate is simple: temperature is the field you cannot see, and it is the field that decides the busbar's life. A busbar looks uniform, but its temperature never is. The current crowds at edges, the heat concentrates at bolted joints, and the hottest spot is almost never where you would guess.
You can instrument a prototype with thermocouples, but that only tells you the temperature where the thermocouples are — and it only tells you after you have built the thing. Simulation flips the order: it predicts the full temperature field before hardware exists, so the design can be changed while changes are cheap. For what temperature actually does to the busbar, see our companion piece on how temperature affects laminated busbar performance.
The thermal limits are not arbitrary either. The insulation's temperature class and the standards that govern temperature rise give you a concrete number to design against. For how those limits are defined, see our guide on laminated busbar standards and certifications.

2. The Physics You Are Simulating

Three things matter, and it is worth being precise about all three.
First, the heat source. Current through a conductor generates Joule heat at a rate of I²R. Because copper's resistivity rises with temperature — ρ = ρ₀ × (1 + α·ΔT) — the resistance increases as the busbar heats, which increases the heat, which increases the temperature further. It is a positive feedback loop, and it is exactly why you cannot model copper with a constant resistivity and expect an accurate answer.
Second, the heat sinks. Heat leaves the busbar three ways: conduction through the copper and into the insulation, natural convection to the surrounding air (with a heat-transfer coefficient typically in the 5–10 W/m²·K range for a naturally cooled busbar), and radiation to the surroundings (governed by the surface emissivity). In many busbar analyses, natural convection and radiation dominate the cooling, not conduction.
Third, the contact resistance. The bolted joints where a busbar connects to a device or another bar are where the hottest spots live. Contact resistance there depends on pressure, surface finish, and plating — and it is genuinely hard to model. Most simplified analyses assume perfect contact, and that assumption is the single largest source of error in busbar thermal simulation. For how bolted joints actually behave, see our guide on bolted copper busbar connections.

3. Choosing the Right ANSYS Tool

ANSYS is not one tool but a family, and picking the right one depends on what you are trying to resolve.
For the busbar itself — a solid conductor with heat generated by current and lost to conduction, convection, and radiation — Ansys Mechanical with a coupled thermal-electric analysis is the natural fit. It solves the electric field to get the current distribution, converts that to Joule heating, and solves the temperature field, all in one coupled model.
For a busbar inside an enclosure with airflow — a power module, a drive cabinet, a data-center rack — Ansys Icepak is the right choice. Icepak is a CFD tool built for electronics cooling, and it handles the natural or forced convection of air around the busbar, which Mechanical does not resolve in detail.
Ansys Fluent is the more general CFD solver, used when the airflow is complex enough that Icepak's electronics-specific simplifications are not enough. And before any of that, Ansys Q3D or Maxwell is often used to extract the parasitic inductance and loss distribution that feed the thermal model — the same low-inductance design work we cover in our deep dive on parasitic inductance in laminated busbars.
The practical rule: busbar-level thermal-electric coupling lives in Mechanical; enclosure-level cooling lives in Icepak; inductance and loss extraction lives in Q3D.

4. Building the Model — Geometry, Materials, and Mesh

A good thermal model starts with what you leave out. Busbar CAD is full of small features — fillets, tiny holes, fasteners — that add mesh complexity without changing the temperature field. De-feature the geometry aggressively, keeping only the features that sit on a real thermal path.
Materials are where accuracy is won or lost. Copper's thermal conductivity and electrical resistivity must be entered as functions of temperature, not single values, because of the feedback loop described earlier. The insulation film's thermal conductivity matters too — it is low, which is good electrically but means it impedes heat flow. Getting these temperature-dependent properties right matters more than getting the mesh extremely fine.
The mesh should be refined where gradients are steep: at bolted joints, in the thin insulation layers, and around the edges where current crowds. A coarse mesh elsewhere is fine. This concentrates the computational effort where the answer is actually being decided.

5. Boundary Conditions and Solving

The boundary conditions are where the simulation connects to reality, and they are worth stating explicitly.
The heat source is the current. In a thermal-electric analysis you apply the current (or voltage) and let the solver compute the I²R loss distribution; alternatively, if you already have a loss number from a separate electromagnetic analysis, you apply that as a volumetric heat generation.
The heat sinks are the environment. You set the ambient temperature, the convection coefficient on the exposed surfaces (5–10 W/m²·K for natural convection, higher for forced air), and the surface emissivity for radiation. These three numbers — ambient, convection, emissivity — are the ones engineers most often get wrong, and they move the answer more than almost anything else in the model.
Then you choose steady-state or transient. Steady-state is right for rated operating conditions — you want the temperature the busbar settles at. Transient is right for overload, inrush, or thermal-cycling duty, where the temperature is still climbing and the time history matters. A busbar sized only for steady-state can still fail a transient overload that the steady-state run never showed.
The output to watch is not the average temperature but the maximum temperature and where it is. The hottest spot — almost always a bolted joint or an edge — is what you compare against the insulation's temperature class and the allowable temperature rise.

6. Summary: Making Simulation Trustworthy

Simulation is only as trustworthy as its inputs. The three things that decide whether a busbar thermal model is right are: temperature-dependent material properties, honest contact-resistance modeling, and correct convection and radiation boundary conditions. Get those right and the simulation predicts temperature well enough to drive design decisions; get them wrong and it produces a confident-looking number that means nothing.
The last step is validation. Simulate, then build, then instrument and measure — and calibrate the model against the test before trusting it on the next design. A simulation that has been validated once is a tool; a simulation that has never been checked against hardware is a guess.
Setting Up Thermal Simulation for Your Busbar?
Send us your current, duty cycle, and cooling method — our engineers will review the thermal approach and come back with design recommendations.
Talk to an Engineer

References & Standards

  1. IEC 60664-1 — Insulation coordination for equipment within low-voltage supply systems. International Electrotechnical Commission. webstore.iec.ch
  2. IEC 60216 — Electrical insulating materials – Thermal endurance properties. International Electrotechnical Commission. webstore.iec.ch
  3. IEC 61439-1 — Low-voltage switchgear and controlgear assemblies. International Electrotechnical Commission. webstore.iec.ch

Prev: Laminated Busbar Manufacturing Process – From Material to Finished Product

Next: Future Trends in Laminated Busbar Technology – SiC, GaN, and Beyond

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