Lesson 5: understanding and working safely with capacitors

Which job can a capacitor perform in electrical work?
a. Produce large current pulses
b. Timing circuits
c. Power factor correction
d. All of the above

All of the above

A capacitor consists of two conductors, usually referred to as plates separated by an insulator called?

dielectric

Which physical factors determines the amount of capacitance

Area of the plates

Distance between the plates

Type of dielectric

The unit of capacitance is the ___ and is symbolized by the letter__?

Farad/ F

A capacitor has the capacitance of one ? when a change of one volt across its plates results in the movement of one coulomb of electrons.

Farad

A charged capacitor has a voltage potential across it. The plate with a deficiency of electrons is the negative plate

False

When a capacitor becomes charged, a potential exists between the plates of the capacitor

True

A capacitor that has a high level of current flow through its insulating material would be considered to have a weak or leaky dielectric

True

Current does not flow through a capacitor, but when connected to an alternating voltage supply, current appears to flow through the capacitor

True

The flow of electrons through the insulating material of a capacitor is called?

leakage

__ charge is the term used to describe the stationary charge stored in a capacitor

Electrostatic

If the electrical stress across a capacitor is excessive, it will be destroyed. Therefore, the __ rating of capacitors should never be exceed

Voltage

? capacitors can be used in either AC or DC circuits.

non- polarized

? capacitors are often used in motor circuits.

Oil-filled non-polarized

Capacitors ? at an exponential rate.

charge and discharge

When a graph is used to represent the rate-of-charge of a capacitor, it is broken down into ? time constants.

5

During each time constant, the curve will see a change equal to ? of the amount of voltage left to reach the fully charged state.

63.2%

The length of one time constant is dependent on the ? of the capacitor and the resistance in series with the capacitor.

farad rating

time constant formula

t= R x C

If an oil-filled capacitor has a terminal with an identification mark, this mark indicates that the terminal is connected to the plate that is located ? the outer metal container or can.

nearer to

Electrolytic capacitors are the ? type.

polarized

Capacitors often have their farad value and ? rating printed on them.

voltage

Which is/are the proper safety rule(s) for working on circuits containing capacitance?

Be sure to discharge the circuit capacitance after the circuit is turned off.
b.Observe polarity marks when connecting capacitors to the circuit.
c.Be sure the capacitor's voltage rating is greater than the peak voltage present in the circuit.