Dielectric Strength
- What is dielectric strength?
- What are the units of dielectric strength?
- Which materials show good dielectric strength?
- What are the applications of dielectric strength?
- What parameters influence the dielectric strength of plastics?
- What factors affect the dielectric strength?
- What standard tests calculate the dielectric strength?
- What methods are used to measure the dielectric strength?
- What are the dielectric strength values of several plastics?
What is dielectric strength?
Dielectric strength reflects the electric strength of insulating materials at various power frequencies. It measures the dielectric breakdown resistance under an applied voltage. It is an indicator of how good a material is as an insulator.
What are the units of dielectric strength?
Dielectric strength is expressed as volts per unit thickness. The SI unit for dielectric strength is:Dielectric strength = V/m
where,
- V is the voltage and
- m is the thickness per unit
The higher the value, the more insulating a material is.
Which materials show good dielectric strength?
- Thermoplastics with Good Dielectric Strength – View All Products
- Rubbers with Good Dielectric Strength – View All Products
- Thermosets with Good Dielectric Strength – View All Products
Note: Most plastics have a good dielectric strength in the order of 100 to 300 kV/cm.
What are the applications of dielectric strength?
Dielectric strength finds applications in the electrical industry. These include:
- Development of materials for energy storage,
- Dielectric materials for capacitors, and
- Thin films in high-speed digital circuitry.
What parameters influence the dielectric strength of plastics?
The dielectric strength of plastics depends on:
- The type of plastic and electrodes,
- The shape of the plastic and electrodes,
- The rate with which the field is increased, and
- The medium that surrounds the insulator.
What factors affect the dielectric strength?
Temperature
- An increase in temperature causes the dielectric strength of an insulation material to decrease.
- Thus, it is inversely proportional to the absolute temperature.
Weibull Characteristic Breakdown Strength vs Temperature for Polymers
Source: ResearchGate
Note: Below room temperature, dielectric strength is independent of temperature change.
Mechanical loading
- Mechanical stress can cause internal flaws that act as leakage paths.
- This causes a decrease in the dielectric strength of loaded insulators.
Details of fabrication
- Flow lines in compression molding or weld lines in an injection molding may serve as paths of least resistance of leakage currents. This reduces the dielectric strength.
- Even nearly invisible minute flaws in a plastics insulator may reduce the dielectric strength. It can be reduced to one-third of this normal value.
What standard tests calculate the dielectric strength?
The most generally used standard tests to calculate dielectric strength are:
- ASTM D149-20: It is a standard test method used to measure the dielectric breakdown voltage. It also measures the dielectric strength of insulating materials. For example, electrical cables, wires, etc.
- IEC 60243-1:2013: It is used to measure the dielectric strength of solid insulating materials. For example, plastics, rubbers, etc.
What methods are used to measure the dielectric strength?
The measurement of dielectric strength is usually carried out by the:
- Short-time method
- Slow rate-of-rise method
- Step-by-step method
Short-time method
In this method, the voltage is applied across the two electrodes. Voltage is then increased at a uniform rate (500 V/sec) until the breakdown occurs.
Slow rate-of-rise method
In this test method, the voltage is applied to the test electrodes. Starting voltage from 50% of the breakdown voltage until breakdown occurs.
Step-by-step method
The voltage is applied to the test electrodes at the preferred starting voltage in steps and duration until breakdown occurs.
Note: The recommended specimen type is a 4-inch plaque or larger. Any specimen thickness can be used.
What are the dielectric strength values of several plastics?
Click to find polymer you are looking for:
A-C | E-M | PA-PC | PE-PL | PM-PP | PS-X
| Polymer Name | Min Value (kV/mm) | Max Value (kV/mm) |
| ABS – Acrylonitrile Butadiene Styrene | 15.70 | 34.00 |
| ABS Flame Retardant | 24.00 | 35.40 |
| ABS High Heat | 12.00 | 20.00 |
| ABS High Impact | 12.00 | 20.00 |
| ABS/PC Blend – Acrylonitrile Butadiene Styrene/Polycarbonate Blend | 15.00 | 70.00 |
| ABS/PC Blend 20% Glass Fiber | 29.90 | 30.00 |
| Amorphous TPI Blend, Ultra-high heat, Chemical Resistant (Standard Flow) | 54.00 | 54.00 |
| Amorphous TPI, Moderate Heat, Transparent | 17.00 | 17.00 |
| Amorphous TPI, Moderate Heat, Transparent (Food Contact Approved) | 17.00 | 17.00 |
| Amorphous TPI, Moderate Heat, Transparent (Mold Release grade) | 14.00 | 14.00 |
| Amorphous TPI, Moderate Heat, Transparent (Powder form) | 17.00 | 17.00 |
| ASA – Acrylonitrile Styrene Acrylate | 40.00 | 105.00 |
| ASA/PC Blend – Acrylonitrile Styrene Acrylate/Polycarbonate Blend | 80.00 | 95.00 |
| ASA/PC Flame Retardant | 90.00 | 90.00 |
| CA – Cellulose Acetate | 8.00 | 15.00 |
| CAB – Cellulose Acetate Butyrate | 10.00 | 16.00 |
| CP – Cellulose Proprionate | 12.00 | 18.00 |
| CPVC – Chlorinated Polyvinyl Chloride | 50.00 | 60.00 |
| ECTFE – Ethylene ChloroTriFluoroEthylene | 14.00 | 14.00 |
| ETFE – Ethylene Tetrafluoroethylene | 7.870 | 7.870 |
| EVA – Ethylene Vinyl Acetate | 27.00 | 28.00 |
| FEP – Fluorinated Ethylene Propylene | 22.00 | 79.00 |
| HDPE – High Density Polyethylene | 17.00 | 24.00 |
| HIPS – High Impact Polystyrene | 12.00 | 24.00 |
| HIPS Flame Retardant V0 | 33.00 | 35.00 |
| Ionomer (Ethylene-Methyl Acrylate Copolymer) | 40.00 | 40.00 |
| LCP – Liquid Crystal Polymer | 32.00 | 39.00 |
| LCP Glass Fiber-reinforced | 22.00 | 30.00 |
| LCP Mineral-filled | 26.00 | 35.00 |
| LDPE – Low Density Polyethylene | 16.00 | 28.00 |
| MABS – Transparent Acrylonitrile Butadiene Styrene | 34.00 | 37.00 |
| PA 11 – (Polyamide 11) 30% Glass fiber reinforced | 40.00 | 40.00 |
| PA 11, Conductive | 24.00 | 55.00 |
| PA 11, Flexible | 24.00 | 55.00 |
| PA 11, Rigid | 24.00 | 55.00 |
| PA 12 (Polyamide 12), Conductive | 24.00 | 55.00 |
| PA 12, Fiber-reinforced | 24.00 | 55.00 |
| PA 12, Flexible | 24.00 | 55.00 |
| PA 12, Glass Filled | 24.00 | 55.00 |
| PA 12, Rigid | 24.00 | 55.00 |
| PA 46 – Polyamide 46 | 15.00 | 25.00 |
| PA 46, 30% Glass Fiber | 25.00 | 35.00 |
| PA 6 – Polyamide 6 | 10.00 | 20.00 |
| PA 6-10 – Polyamide 6-10 | 16.00 | 26.00 |
| PA 66 – Polyamide 6-6 | 20.00 | 30.00 |
| PA 66, 30% Glass Fiber | 25.00 | 25.00 |
| PA 66, 30% Mineral filled | 25.00 | 30.00 |
| PA 66, Impact Modified, 15-30% Glass Fiber | 11.80 | 21.00 |
| PA 66, Impact Modified | 18.00 | 90.00 |
| PA 66, Carbon Fiber, Long, 30% Filler by Weight | 1.300 | 1.300 |
| PAI – Polyamide-Imide | 23.60 | 24.00 |
| PAI, 30% Glass Fiber | 27.60 | 34.00 |
| PAR – Polyarylate | 17.00 | 17.00 |
| PARA (Polyarylamide), 30-60% glass fiber | 23.70 | 30.00 |
| PBT – Polybutylene Terephthalate | 15.00 | 30.00 |
| PBT, 30% Glass Fiber | 50.00 | 50.00 |
| PC (Polycarbonate) 20-40% Glass Fiber | 20.00 | 20.00 |
| PC (Polycarbonate) 20-40% Glass Fiber Flame Retardant | 17.00 | 38.00 |
| PC – Polycarbonate, high heat | 16.00 | 35.00 |
| PCTFE – Polymonochlorotrifluoroethylene | 21.00 | 24.00 |
| PE – Polyethylene 30% Glass Fiber | 19.70 | 19.70 |
| PEEK – Polyetheretherketone | 20.00 | 20.00 |
| PEEK 30% Carbon Fiber-reinforced | 18.50 | 19.00 |
| PEEK 30% Glass Fiber-reinforced | 15.00 | 24.00 |
| PEI – Polyetherimide | 28.00 | 33.00 |
| PEI, 30% Glass Fiber-reinforced | 25.00 | 30.00 |
| PEI, Mineral Filled | 20.00 | 25.00 |
| PEKK (Polyetherketoneketone), Low Cristallinity Grade | 23.60 | 23.60 |
| PESU – Polyethersulfone | 16.00 | 80.00 |
| PESU 10-30% glass fiber | 14.60 | 40.00 |
| PET – Polyethylene Terephthalate | 60.00 | 60.00 |
| PET, 30% Glass Fiber-reinforced | 16.80 | 22.50 |
| PETG – Polyethylene Terephthalate Glycol | 45.00 | 45.00 |
| PFA – Perfluoroalkoxy | 2.100 | 2.200 |
| PGA – Polyglycolides | 34.00 | 80.00 |
| PI – Polyimide | 22.00 | 27.60 |
| PMMA – Polymethylmethacrylate/Acrylic | 15.00 | 22.00 |
| PMMA (Acrylic) High Heat | 18.70 | 20.00 |
| PMMA (Acrylic) Impact Modified | 15.00 | 60.00 |
| PMP – Polymethylpentene | 28.00 | 30.00 |
| PMP 30% Glass Fiber-reinforced | 23.60 | 23.60 |
| PMP Mineral Filled | 23.60 | 23.60 |
| POM – Polyoxymethylene (Acetal) | 13.80 | 20.00 |
| POM (Acetal) Impact Modified | 19.00 | 19.00 |
| POM (Acetal) Low Friction | 16.00 | 16.00 |
| PP – Polypropylene 10-20% Glass Fiber | 30.00 | 45.00 |
| PP, 10-40% Mineral Filled | 30.00 | 70.00 |
| PP, 10-40% Talc Filled | 30.00 | 70.00 |
| PP, 30-40% Glass Fiber-reinforced | 30.00 | 45.00 |
| PP (Polypropylene) Copolymer | 20.00 | 28.00 |
| PP (Polypropylene) Homopolymer | 20.00 | 28.00 |
| PP, Impact Modified | 20.00 | 28.00 |
| PPA – Polyphthalamide | 20.80 | 20.90 |
| PPA, 30% Mineral-filled | 20.00 | 22.00 |
| PPA, 33% Glass Fiber-reinforced | 20.00 | 22.00 |
| PPA, 33% Glass Fiber-reinforced – High Flow | 18.00 | 20.00 |
| PPA, 45% Glass Fiber-reinforced | 22.00 | 24.00 |
| PPE – Polyphenylene Ether | 20.00 | 22.00 |
| PPE, 30% Glass Fiber-reinforced | 22.00 | 22.00 |
| PPE, Flame Retardant | 16.00 | 25.00 |
| PPE, Impact Modified | 1.000 | 1.100 |
| PPS – Polyphenylene Sulfide | 11.00 | 24.00 |
| PPS, 20-30% Glass Fiber-reinforced | 13.80 | 17.00 |
| PPS, 40% Glass Fiber-reinforced | 17.00 | 17.00 |
| PPS, Glass fiber & Mineral-filled | 13.00 | 13.00 |
| PPSU – Polyphenylene Sulfone | 14.20 | 20.00 |
| PS (Polystyrene) 30% glass fiber | 15.00 | 19.70 |
| PS (Polystyrene) Crystal | 16.00 | 28.00 |
| PSU – Polysulfone | 15.00 | 10.00 |
| PSU, 30% Glass finer-reinforced | 16.90 | 40.00 |
| PTFE – Polytetrafluoroethylene | 17.00 | 24.00 |
| PTFE, 25% Glass Fiber-reinforced | 20.00 | 20.00 |
| PVC, Plasticized | 10.00 | 30.00 |
| PVC, Plasticized Filled | 10.00 | 30.00 |
| PVC Rigid | 10.00 | 40.00 |
| PVDF – Polyvinylidene Fluoride | 10.00 | 27.00 |
| SAN – Styrene Acrylonitrile | 12.00 | 24.00 |
| SAN, 20% Glass Fiber-reinforced | 19.70 | 20.00 |
| SMA – Styrene Maleic Anhydride | 16.00 | 16.00 |
| SMA, 20% Glass Fiber-reinforced | 21.00 | 21.00 |
| SMMA – Styrene Methyl Methacrylate | 19.70 | 19.70 |
| UHMWPE – Ultra High Molecular Weight Polyethylene | 28.00 | 28.00 |