Properties of Inductors and Capacitors 030201b Flashcards
What is an inductor?
An electrical component that stores energy in its electromagnetic field.
What is the construction of an inductor?
An insulated conductor wound around a core.
What types of material is the core of a coil composed of?
Magnetic (iron)
Non-magnetic (air, ceramic, plastic)
What is an inductor normally known as?
Coil, Solenoid or Reactor.
What are some examples of electrical equipment that utilize coils?
Motors
Transformers
Solenoids that actuate valves or strikers
Relay coils
Magnetic starter coils
Electromagnetic lighting ballasts
Line reactors for variable frequency drives. (VFD)
What is induction?
The process where voltage is produced by the relative motion between a conductor and a magnetic field.
What is inductance?
The property of a circuit that opposes change in current.
What does Faraday’s Law of Induction state?
The amount of induced EMF is directly proportional to the rate of change of flux.
What three factors impact the rate of change of flux in an alternator?
Rotational frequency
Flux density
Angle of cut.
What are two types of induction?
Mutual induction
Self-induction
What is mutual induction?
The generation of an EMF in one conductor or circuit by a change of flux around a separate conductor or circuit.
What is self-induction?
The generation of an EMF in a conductor or circuit by a change of flux density around that conductor or circuit.
What is Lenz’s Law?
That an induced electric current flows in a direction such that the current opposes the change that induced it
What does CEMF stand for?
Counter Electromotive Force
What is the formula for CEMF?
CEMF = (Change in current / Change in Time) X Inductance
What is the symbol for Inductance and what is inductance measured in?
The symbol for Inductance is L. Inductance is measured in Henry’s represented by (h)
What factors affect inductance of a coil?
Number of turns of a conductor in a coil. (N)
Permeability of the core material. (μ)
Cross sectional area of the core. (A)
Length of the core (ℓ)
What is the formula for inductance?
L = (NxN) x μ x A / ℓ
What is a basic capacitor?
A circuit component made up of two plates of conducting material separated by a narrow gap or space. Between the plates is an insulating material known as a dielectric.
What are the two main types of capacitors?
Polarized and non-polarized.
What are all the types of non-polarized capacitors?
Air
Oil-filled
Paper
Plastic film
Mica
Ceramic
Aluminum Electrolytic
Tantalum Electrolytic
What are four applications of capacitors?
Timers
Rectifier Smoothing and Filtering
Power Factor Correction
Motor Starting
What is capacitance?
A capacitor’s ability to store an electric charge. Symbol for capacitance is C (italicized)
What is capacitance measured in?
Measured in Farad (F)
How do you convert a Farad to a microfarad?
Microfarad (μF) 10^-6
What three factors affect capacitance?
The dielectric constant (K) of the material that separates the plates.
The area of the plates (A)
The distance between the plates (d)
What is the formula for capacitance?
C = K x A / d
What is a dielectric constant?
Is a rating of a dielectric insulating material’s ability to polarize and store charge compared to air.
What is dielectric strength measured in?
Kilovolts per millimetre (kV/mm)
What does WVDC stand for?
Working volts direct current.
What can the working volts direct current value be considered as on a sine wave?
The peak voltage or max voltage value.
