Capacitors

Electrical Devices
HVA228 – ADVANCED TROUBLESHOOTING

DEFINING LOADS
LOADS
• In electrical work, load is the name

given to any electrical device that
consumes electricity to do electrical
work.
• Loads can be Resistive, Inductive and

Capacitive.
• Examples include motors and solenoids.

Capacitors
Capacitors
• The capacitor consists of two aluminium

plates with an insulator between them.
• The insulator prevents electrons from

flowing from one plate to the other, but it
permits the storage of electrons.
• Capacitors are used to boost the starting

torque or running efficiency of single-
phase motors.
Capacitors
• There are two types of capacitors primarily used in

the industry:
• The electrolytic or starting capacitor
• The oil-filled or running capacitor
• A microfarad is the unit of measurement for the strength

of a capacitor
• The major difference between the two types of

capacitors is in their application.
Electrolytic Capacitors
• Starting capacitors are usually in a plastic case consisting of two

aluminium electrodes (plates) with a chemically treated paper,
impregnated with a nonconductive electrolyte, between them.
• They can be purchased in the range from 50 to 600 microfarads (𝜇F)

and from 120 to 300 Volts.
• The electrolytic capacitor is used to assist a single-phase motor in

starting.
• A starting capacitor is built in a relatively small case with a dielectric –

a nonconductor of electric current. It is used for only a short period of
time on each cycle of the motor.
• Therefore, a starting capacitor has no need to dissipate heat, although

its capacity is larger than the running capacitor.
Oil-Filled Capacitors
• The oil-filled capacitor consists of two aluminium electrodes with paper

between them and an oil-filled capacitor case.
• It is available in microfarad ranges of about 2 to 80 and voltage ranges of

240 to 550.
• The oil-filled capacitor can be used for small or moderate torque starting
but it is more commonly used to increase a motor’s running efficiency.
• The running capacitor is designed to stay in the motor circuit for the
entire cycle of operation. Therefore, it must have some means of
dissipating heat. The oil is in the capacitor case is used for this purpose.
• The oil-filled capacitor is physically larger than the starting capacitor but
smaller in capacity than the starting capacitor and usually contained
within a metal case.
CAPACITOR DIAGRAM
TROUBLESHOOTING
CAPACITORS
• Short capacitor life and malfunctions can be caused by

several different factors.
• High voltage can cause a capacitor to overheat, which

can damage the plates and short the electrodes.
• Starting capacitors can be damaged by a faulty starting

apparatus that would keep the capacitor in the line
circuit long enough to damage the capacitor.
• Excessive temperature can shorten the life of capacitors

or cause permanent damage due to poor ventilation,
starting cycles that are too long, or starting cycles that
occur too frequently.
TROUBLESHOOTING
CAPACITORS
• There are several methods of testing capacitors
• A capacitor can be checked by using an ohmmeter
• A digital ohmmeter will go to a small resistance

reading back to a larger resistance reading if the
capacitor is good
• An ohmmeter will read 0 if the capacitor has

shorted.
• If there is not reading, the capacitor is open

TROUBLESHOOTING CAPACITORS
• You can test a capacitor by briefly applying voltage to it, reading

the amperage and then substituting the valves into the formula
below.
• We can obtain the exact capacitance using this formula
2,650 𝑋 𝐴𝑀𝑃𝐸𝑅𝐸𝑆
• MICROFARADS =
𝑉𝑂𝐿𝑇𝐴𝐺𝐸
TROUBLESHOOTING CAPACITORS
• Capacitors used on single-phase motors are designed specifically to assist the motor in proper operation.
• However, in some cases it is impossible to replace a capacitor with an exact replacement.
• If this situation occurs, use the following guidelines for replacing the capacitor:
• The voltage of any capacitor used for replacement must be equal to or greater than that of the capacitor being replaced.
• The strength of the starting capacitor replacement must be at least equal to but not more than 20% greater than that of
the capacitor being replaced.
• The strength of the running capacitor replacement must may vary by plus or minus 10% of the strength of the capacitor
being replaced.
• If the capacitors are installed in parallel, the sum of the capacitors is the total capacitance.
• The total capacitance of capacitors in series is less than the individual capacitance of the capacitors.
CAPACITORS IN PARALLEL
CAPACITORS IN SERIES
EXERCISE – CAPACITANCE
• Calculate the total capacitance of the following capacitors in series
and parallel:
• 10 𝜇F and 15 𝜇F
• 20 𝜇F and 50 𝜇F
• 5 𝜇F , 25 𝜇F and 40 𝜇F
• 30 𝜇F , 60 𝜇F and 80 𝜇F
ACTIVITY
CONNECT TWO CAPACITORS IN SERIES & PARALLEL.

PERFORM THE REQUIRED CALCULATIONS FOR THEIR TOTAL CAPACITANCE.

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Electrical Devices

HVA228 – ADVANCED TROUBLESHOOTING

• In electrical work, load is the name

• Loads can be Resistive, Inductive and

• Examples include motors and solenoids.

• The capacitor consists of two aluminium

• The insulator prevents electrons from

• Capacitors are used to boost the starting

• There are two types of capacitors primarily used in

• A microfarad is the unit of measurement for the strength

• The major difference between the two types of

• Starting capacitors are usually in a plastic case consisting of two

• They can be purchased in the range from 50 to 600 microfarads (𝜇F)

• The electrolytic capacitor is used to assist a single-phase motor in

• A starting capacitor is built in a relatively small case with a dielectric –

• Therefore, a starting capacitor has no need to dissipate heat, although

• The oil-filled capacitor consists of two aluminium electrodes with paper

• It is available in microfarad ranges of about 2 to 80 and voltage ranges of

• Short capacitor life and malfunctions can be caused by

• High voltage can cause a capacitor to overheat, which

• Starting capacitors can be damaged by a faulty starting

• Excessive temperature can shorten the life of capacitors

• There are several methods of testing capacitors

• A capacitor can be checked by using an ohmmeter

• A digital ohmmeter will go to a small resistance

• An ohmmeter will read 0 if the capacitor has

• If there is not reading, the capacitor is open

• You can test a capacitor by briefly applying voltage to it, reading

• However, in some cases it is impossible to replace a capacitor with an exact replacement.

• Calculate the total capacitance of the following capacitors in series

CONNECT TWO CAPACITORS IN SERIES & PARALLEL.

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