Dissipation Factor

1. What is dissipation factor (DF)?
2. What is the formula to calculate dissipation factor of an insulator?
3. How power factor is related to dissipation factor?
4. What factors influence dissipation factor?
5. What are the applications of dissipation factor?
6. What are the test methods to calculate dissipation factor?
7. What are the dissipation factor values of several plastics?

What is dissipation factor (DF)?

Dissipation factor (DF) is defined as the reciprocal of the ratio between the insulating materials’ capacitive reactance to its resistance (Equivalent Series Resistance or ESR) at a specified frequency. In other words, it is defined as a ratio between the permittivity and the conductivity of an electrically insulating material.

DF is the electrical property of plastics and other electrically insulating materials. It measures the electrical energy absorbed and lost (power dissipation) when an electrical current is applied to an insulating material. Most of the absorbed energy is dissipated as heat. It is a dimensionless measure and hence no units. The property is also referred to as the:

• tangent of the loss angle,
• loss tangent,
• tan delta (tan δ), and
• approximate power factor.

The dissipation factor indicates the inefficiency of material to hold energy or behave as an insulating material. The lower the dissipation factor, the more efficient the insulator system. Most plastics have a relatively lower dissipation factor at room temperature.

What is the formula to calculate dissipation factor of an insulator?

The dissipation factor is the tangent of the loss angle of the insulating material. The formula to calculate the dissipation factor of an insulator is as follows:

Where:

• DF is the dissipation factor or loss tangent
• δ is the phase angle between the voltage and current waveforms in the insulator
• I_R is the resistive current
• I_C is the capacitive current
• V is the applied voltage
• R is the voltage-dependent resistance
• ω is the angular frequency of the AC voltage applied to the insulator
• C is the capacitance of the insulator

The tan δ measured at a frequency ω and voltage V, is the ratio of the resistive (I_R) and the capacitive (I_C) currents as shown in the above formula. In an ideal capacitor without any dielectric losses, the insulation current is exactly 90° leading. This is according to the applied voltage. Dielectric becomes less than 100% efficient when the current wave begins to lag the voltage in direct proportion.

The dielectric phase angle, θ, is the angular difference in phase between the sinusoidal alternating potential difference applied to a dielectric and the component of the resulting current having the same period as the potential difference.

This means that when an alternating current is applied across an insulating material, the resulting alternating current passing through it (no matter how small) will be at a different phase than the voltage. The amount of current wave that deviates from being 90° out of phase with voltage is defined as the dielectric loss angle (90°- θ). The tangent of this angle δ is known as the loss tangent or dissipation factor.

How power factor is related to dissipation factor?

The power factor (PF) of an insulator is defined as the ratio of power dissipated in watts to total charging volt-amperes. It is also the cosine of the angle between the voltage applied and the resulting current. This is the dielectric phase angle θ. The formula to calculate PF is as follows:

Where:

• PF is the power factor
• tan δ is the dissipation factor

If the dissipation factor (tan δ) is very small, i.e., less than 10%, then the dissipation factor and the power factor differ in a negligible amount and can be assumed to have the same value.

Dielectric loss factor or loss factor of a material is another frequently used term. It is the product of the dielectric constant and the dissipation factor. It is related to the total loss of power occurring in plastics or any other insulating materials. It indicates how easily the material will heat up in a high-frequency field.

What factors influence dissipation factor?

• Frequency — The changes in dielectric constant and loss index with frequency are produced by the dielectric polarization. This exists in the material.


• Temperature — The dissipation factor increases with an increase in temperature or humidity. This increase is often dramatic. It can even be destructive at the glass transition temperature of plastics.


• Humidity — An increase in humidity increases the extent of interfacial polarization of the material. This increases conductance. The effects of humidity are caused by the absorption of water. It can also be caused by the formation of an ionized water film on the surface.


• Weather conditions — Rain, severe winds, impurities in the atmosphere, UV light, heat, etc., may change the surface of an insulating material. The changes can be either physical (roughening, cracking, etc.,) or chemical. This leads to water penetration into the material volume.

What are the applications of dissipation factor?

• The low dissipation factor indicates high-performance electrical or electronic systems. Low values mean better dielectric materials with less dielectric heating.
• It is important for plastic insulators in high-frequency applications. For e.g., radar equipment or microwave parts.
• The high dissipation factors are important for polymers that are to be heated in a radio frequency or microwave oven. Such polymers are used for welding, drying, etc.
• The material used for high capacitance requires a high dielectric constant and low dissipation factor.
• DF can be used to assess the quality of insulating material in several applications. These include cable, terminations, joints, etc., for moisture content, deterioration, etc. Here the initial values of the DF of the tested material are important.

What are the test methods to calculate dissipation factor?

• ASTM D2520 — It determines the complex permittivity (dielectric constant and dissipation factor). This is for solid electrical insulating materials. It is measured at microwave frequencies and temperatures of 1650 °C.


• ASTM D150 — It determines the AC loss characteristics and permittivity (dielectric constant). This is for solid electrical insulation.


• IEC 62631-2-1 — It determines the dielectric and resistive properties. The measurement is for solid insulating materials. It also determines the relative permittivity and dissipation factor. It is measured at technical frequencies of 0,1 Hz - 10 MHz. This is done by AC methods.

Test procedure

• A sample is placed between two metallic plates and capacitance is measured. The sample must be flat and larger than the 50mm (2 in) circular electrodes used for the measurement.
• A second run is measured without the specimen between the two electrodes.
• The ratio of the power dissipated in the test material to the power applied is the dissipation factor.
• The test can be conducted at different frequencies, often between the 10Hz and 2MHz range.

What are the dissipation factor values of several plastics?

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Polymer Name	Min Value (x 10-4)	Max Value (x 10-4)
ABS - Acrylonitrile Butadiene Styrene	50.0	190.0
ABS Flame Retardant	70.0	90.0
ABS High Heat	20.0	350.0
ABS High Impact	20.0	350.0
ABS/PC Blend - Acrylonitrile Butadiene Styrene/Polycarbonate Blend	70.0	200.0
ABS/PC Blend 20% Glass Fiber	20.0	90.0
ABS/PC Flame Retardant	40.0	70.0
Amorphous TPI Blend, Ultra-high heat, Chemical Resistant (Standard Flow)	0.001	0.001
ASA - Acrylonitrile Styrene Acrylate	90.0	340.0
ASA/PC Blend - Acrylonitrile Styrene Acrylate/Polycarbonate Blend	20.0	190.0
ASA/PC Flame Retardant	110.0	170.0
CA - Cellulose Acetate	100.0	1000.0
CAB - Cellulose Acetate Butyrate	100.0	400.0
CP - Cellulose Proprionate	60.0	300.0
CPVC - Chlorinated Polyvinyl Chloride	100.0	200.0
ECTFE - Ethylene Chlorotrifluoroethylene	130.0	170.0
ETFE - Ethylene Tetrafluoroethylene	6.0	100.0
EVA - Ethylene Vinyl Acetate	130.0	1000.0
EVOH - Ethylene Vinyl Alcohol	1800.0	2200.0
FEP - Fluorinated Ethylene Propylene	7.0	7.0
HDPE - High Density Polyethylene	3.0	20.0
HIPS - High Impact Polystyrene	4.0	20.0
HIPS Flame Retardant V0	5.0	50.0
Ionomer (Ethylene-Methyl Acrylate Copolymer)	20.0	20.0
LCP - Liquid Crystal Polymer	40.0	40.0
LCP Glass Fiber-reinforced	60.0	300.0
LCP Mineral-filled	70.0	280.0
LDPE - Low Density Polyethylene	3.0	4.0
MABS - Transparent Acrylonitrile Butadiene Styrene	2.8	3.0
PA 11 - (Polyamide 11) 30% Glass fiber reinforced	0.03	0.03
PA 11, Conductive	0.05	0.25
PA 11, Flexible	0.05	0.25
PA 11, Rigid	0.05	0.25
PA 12 (Polyamide 12), Conductive	0.05	0.25
PA 12, Fiber-reinforced	0.05	0.25
PA 12, Flexible	0.05	0.25
PA 12, Glass Filled	0.05	0.25
PA 12, Rigid	0.05	0.25
PA 46 - Polyamide 46	190.0	600.0
PA 46, 30% Glass Fiber	23.0	90.0
PA 6 - Polyamide 6	100.0	600.0
PA 6-10 - Polyamide 6-10	400.0	400.0
PA 66 - Polyamide 6-6	100.0	400.0
PA 66, 30% Glass Fiber	100.0	1500.0
PA 66, 30% Mineral filled	200.0	1500.0
PA 66, Impact Modified, 15-30% Glass Fiber	130.0	200.0
PA 66, Impact Modified	100.0	2000.0
Polyamide semi-aromatic	3.0	3.1
PAI - Polyamide-Imide	60.0	710.0
PAI, 30% Glass Fiber	220.0	500.0
PAR - Polyarylate	20.0	200.0
PBT - Polybutylene Terephthalate	10.0	200.0
PBT, 30% Glass Fiber	20.0	120.0
PC (Polycarbonate) 20-40% Glass Fiber	9.0	75.0
PC (Polycarbonate) 20-40% Glass Fiber Flame Retardant	9.0	100.0
PC - Polycarbonate, high heat	69.0	100.0
PC/PBT blend, Glass Filled	100.0	200.0
PCTFE - Polymonochlorotrifluoroethylene	10.0	250.0
PE - Polyethylene 30% Glass Fiber	20.0	80.0
PEEK - Polyetheretherketone	30.0	30.0
PEEK 30% Carbon Fiber-reinforced	29.0	32.0
PEEK 30% Glass Fiber-reinforced	20.0	20.0
PEI - Polyetherimide	13.0	25.0
PEI, 30% Glass Fiber-reinforced	15.0	53.0
PEI, Mineral Filled	10.0	15.0
PEKK (Polyetherketoneketone), Low Cristallinity Grade	0.004	0.004
PESU - Polyethersulfone	10.0	140.0
PESU 10-30% glass fiber	70.0	100.0
PET - Polyethylene Terephthalate	20.0	200.0
PET, 30% Glass Fiber-reinforced	120.0	1680.0
PET, 30/35% Glass Fiber-reinforced, Impact Modified	1.500	1.500
PETG - Polyethylene Terephthalate Glycol	20.0	300.0
PE-UHMW - Polyethylene -Ultra High Molecular Weight	2.0	2.0
PFA - Perfluoroalkoxy	2.0	2.0
PI - Polyimide	18.0	50.0
PMMA - Polymethylmethacrylate/Acrylic	200.0	200.0
PMMA (Acrylic) High Heat	400.0	600.0
PMMA (Acrylic) Impact Modified	300.0	400.0
PMP - Polymethylpentene	0.7	30.0
POM - Polyoxymethylene (Acetal)	50.0	110.0
POM (Acetal) Impact Modified	50.0	250.0
POM (Acetal) Low Friction	20.0	90.0
POM (Acetal) Mineral Filled	1.500	1.600
PP - Polypropylene 10-20% Glass Fiber	10.0	20.0
PP, 10-40% Mineral Filled	7.0	11.0
PP, 10-40% Talc Filled	7.0	11.0
PP, 30-40% Glass Fiber-reinforced	10.0	20.0
PP (Polypropylene) Copolymer	3.0	5.0
PP (Polypropylene) Homopolymer	3.0	5.0
PP, Impact Modified	3.0	5.0
PPA - Polyphthalamide	270.0	270.0
PPA, 33% Glass Fiber-reinforced – High Flow	0.014	0.016
PPA, 45% Glass Fiber-reinforced	0.9	0.2
PPE - Polyphenylene Ether	4.0	9.0
PPE, 30% Glass Fiber-reinforced	10.0	15.0
PPE, Flame Retardant	7.0	31.0
PPS - Polyphenylene Sulfide	4.0	30.0
PPS, 20-30% Glass Fiber-reinforced	10.0	32.0
PPS, 40% Glass Fiber-reinforced	13.0	20.0
PPS, Glass fiber & Mineral-filled	70.0	580.0
PPSU - Polyphenylene Sulfone	17.0	50.0
PS (Polystyrene) 30% glass fiber	5.0	28.0
PS (Polystyrene) Crystal	1.0	28.0
PS, High Heat	1.0	28.0
PSU - Polysulfone	8.0	64.0
PSU, 30% Glass finer-reinforced	40.0	60.0
PTFE - Polytetrafluoroethylene	2.0	2.0
PTFE, 25% Glass Fiber-reinforced	5.0	5.0
PVC, Plasticized	400.0	1600.0
PVC, Plasticized Filled	400.0	1600.0
PVC Rigid	60.0	200.0
PVDF - Polyvinylidene Fluoride	200.0	1700.0
SAN - Styrene Acrylonitrile	70.0	100.0
SAN, 20% Glass Fiber-reinforced	10.0	100.0
SMA - Styrene Maleic Anhydride	40.0	40.0
SMMA - Styrene Methyl Methacrylate	400.0	400.0