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What are the electrical insulation materials with low dielectric loss?

by adam•

Hey everyone, let’s talk about electrical insulation materials—specifically the ones that tick a huge box: low dielectric loss. If you’re in the power electronics, transformer, or high-voltage equipment game, you know how annoying dielectric loss can be. It’s that little energy drain that turns into heat, over time wearing down your gear, cranking up energy bills, and messing with performance. I’m a supplier of these materials, and I get it—customers don’t just want any insulation; they want stuff that’s efficient, durable, and won’t leave them stuck troubleshooting later. Electrical Insulation Material

First off, let’s keep it real: dielectric loss (we often call it tan delta, yeah that’s the common shorthand) is the ratio of energy lost as heat to the total energy passing through the insulation. Lower tan delta means way less wasted energy, so your equipment runs cooler, lasts longer. No wonder everyone’s hunting for low loss options these days, especially with the push for renewable energy (solar inverters, wind turbine parts, all that) where efficiency is non-negotiable.

Let’s dive into the top materials we supply, break down why they’re great for low loss, and what makes them stand out.

  1. Cross-Linked Polyethylene (XLPE)
    This one’s a workhorse for medium and high-voltage cables. When we first started working with XLPE decades ago, it blew up because its dielectric loss is super low—like 0.0005 to 0.002 at 50/60 Hz, way lower than older materials like PVC. Why so low? It’s a non-polar polymer, meaning its molecules don’t have that uneven charge distribution that causes energy to leak. Wait, but not all XLPE is equal. We specialize in the upgraded grade—cross-linked properly, no residual byproducts from manufacturing. Those byproducts can raise loss, so we make sure our XLPE’s processed right. It’s also flexible enough for cable installation, resists moisture (another big loss culprit), and works in temps from -40°C to 90°C. Perfect for underground power lines, renewable energy cable runs, even aerospace wiring where weight and efficiency matter.

  2. Fluoropolymers (Specifically PTFE and FEP)
    If you need high temps, fluoropolymers are your go-to. PTFE (Teflon, though we call it by its industry name more often) has a dielectric loss around 0.0002 to 0.0005 at 1 MHz—crazy low. FEP (fluorinated ethylene propylene) is similar, a tiny bit higher but still way under most alternatives. These are super non-polar too, so almost no energy gets wasted. They handle extreme heat: PTFE up to 260°C, FEP up to 200°C, and they’re chemically resistant to oils, acids, whatever. That makes them ideal for motor windings in industrial equipment, high-frequency electronics (like 5G components—wait, 5G runs at high frequencies, so low loss is make-or-break for signal integrity), and aerospace wiring where heat and chemicals are a problem. The only catch? They’re a bit pricier than XLPE, but the energy savings and long lifespan more than make up for it. We’ve got both solid films and extruded wires, so customers can pick what fits their project.

  3. Polypropylene (PP)
    Don’t sleep on polypropylene—its dielectric loss is like 0.0002 to 0.0003 at 1 kHz, super low for a thermoplastic. It’s cheap, lightweight, easy to mold, and non-polar. That’s why it’s the star of capacitor films—film capacitors use polypropylene all the time because low loss means no heat buildup inside the capacitor, so they last way longer than ones with higher loss insulation. We supply both biaxially oriented polypropylene (BOPP) film, which is stretched for better strength and uniformity, and specialty grades for high-voltage capacitors. It’s also used in low-voltage wiring, power distribution boxes, and even solar panel encapsulation. One thing to note: PP isn’t great above 105°C, so it’s for lower temp applications, but for that sweet spot, it’s unbeatable on cost and loss.

  4. Silicone Rubber (VMQ)
    Silicone’s not just for seals—its dielectric loss is around 0.001 to 0.003 at 50 Hz, which is lower than most organic rubbers. It’s polar, but the molecular structure is so flexible that charge movement is limited, so loss stays low. It’s super flexible, resists ozone and UV, works from -60°C to 200°C. That makes it perfect for gaskets in switchgear, cable terminations, and soft insulation for sensors. We also supply filler-modified silicone grades that tweak loss even lower for high-frequency sensor applications. The main downside? It’s more expensive than natural rubber, but for outdoor equipment that deals with weather extremes, the low loss and durability make it worth it.

  5. Polyimide (PI) Films and Composites
    Polyimide is the high-performance guy, with dielectric loss around 0.001 to 0.002 at 1 MHz. It’s polar, but tightly cross-linked molecules restrict dipole movement, so loss stays manageable. It handles up to 250°C, is mechanically strong, and chemically inert. We use PI for high-temperature motor and transformer windings, aerospace wiring, and printed circuit boards (PCBs) for industrial electronics where heat is an issue. It’s thinner than many other high-temp insulators, so you get more compact designs without losing insulation performance. A lot of customers come to us when their old insulation melts down in industrial furnaces or aerospace systems—PI solves that without cranking up energy loss.

Wait, let’s talk about what makes low dielectric loss materials different from regular insulation. A lot of generic insulators are cheap, but their tan delta is higher—so over time, that heat builds up, leading to thermal runaway, shorter equipment life, and higher operating costs. For example, a transformer using an insulation with tan delta 0.01 loses way more energy than one with 0.001, and that adds up over thousands of hours of operation. For a wind farm with 100 transformers, that’s a ton of wasted electricity every year. That’s why we don’t just sell “insulation”—we sell materials that boost your bottom line by reducing energy waste.

Now, what should you look for when choosing a low dielectric loss material? It’s not just tan delta alone. Temperature matters—tan delta changes with heat. At high temps, some materials’ loss spikes, so if you’re running equipment hot, you need a material whose low loss stays consistent at that temp. Frequency is another big one: high-frequency apps (5G, radar, high-speed inverters) have way higher energy loss at high frequencies, so a material that’s great at 50 Hz might not cut it at 1 MHz. Moisture is also a killer—water has high dielectric loss, so any insulation that absorbs moisture will see its loss jump. That’s why we make sure our XLPE and silicone are moisture-resistant, and our fluoropolymers are completely non-absorbent. Also, mechanical strength: if your insulation tears during installation, it’s useless, so we test all our materials for tensile strength and flexibility too.

I’ve had a lot of customers come to me frustrated because they tried a “low cost” insulation, only to have equipment fail after 2 years. One example: a solar inverter manufacturer was using a PVC insulation for their internal wiring. At high operating temps, PVC’s tan delta jumped to 0.01, so the inverter ran 10°C hotter, cutting its lifespan by 5 years. They switched to our XLPE wires, and now their inverters run 5°C cooler, with 30% less energy loss in the wiring. That’s the kind of win we love to see.

Another example: a wind turbine operator had issues with transformer insulation overheating. Their old paper-oil insulation had tan delta of 0.008, so the transformers were losing 2% of their output as heat. We supplied a low-loss ester oil (wait, ester oils have lower loss than mineral oil, right?) combined with our cross-linked polyethylene barriers. Now their tan delta is 0.002, so they’re saving thousands of dollars a year in energy.

We also work on custom blends—some customers have weird specs, so we can mix polymers to get low loss plus specific mechanical or thermal properties. For example, a customer making high-frequency sensors needed a material with tan delta under 0.0005 at 10 GHz, and flexibility to wrap around small wires. We blended PTFE with a small amount of fluorinated rubber, hit exactly their specs, and kept the loss super low.

Now, if you’re tired of dealing with overheating equipment, high energy bills, and frequent insulation failures, we’ve got you. We don’t just stock standard materials—we test every batch to make sure the dielectric loss meets your needs, and we can help you pick the right material for your specific application, whether it’s a 5G PCB, a transformer for a power plant, or a wind turbine cable. No guesswork, no jargon we can’t explain, just materials that work.

If you’re ready to chat about your project, send us a message to connect and discuss your requirements. We can share sample materials, test data, and even help you calculate the energy savings you’ll get with low dielectric loss insulation. Don’t let wasted energy and broken equipment hold your projects back—let’s find the right insulation for you.

Phenolic Resin References:

  1. Nelson, J.K. (2014). Dielectric Polymer Materials for High-Voltage Applications. Elsevier.
  2. CRC Handbook of Electrical Insulation Materials. (2021). CRC Press.
  3. "Dielectric Loss in Polymers: Fundamentals and Applications." IEEE Transactions on Dielectrics and Electrical Insulation, vol. 22, no. 3, 2015, pp. 1567-1580.
  4. Kutz, M. (Ed.). (2011). Electrical Insulation Materials Handbook. McGraw-Hill.
  5. "Fluoropolymers for High-Frequency Electrical Applications." Journal of Applied Polymer Science, vol. 132, no. 12, 2015, pp. 41234.

Zhejiang Nansu Synthetic Materials Co., Ltd.
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