Transcript AVOP-ELEKTRO-SKA-012

Tutorial: Mechanic - electrician
Topic:
Basics of electrical engineering
the 2nd. year
Three-phase current
Fuse
Prepared by: Škarka Miloš
Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002
je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.
Is an electric device protecting an electro technical
mechanism or circuit against damage by an excessive
current and it is a component for protection by automatic
disconnection from the source.
Schematic symbol of the fuse
Fuse insertion
The principle of the securing means that fuse is
the weakest link of the electric circuit. In case of
warm up with higher than allowed current the
conductor inside the fuse is blown and electric
circuit is disconnected. Fuse (also fuse shell or
fuse insertion) is disposable, has to be replaced
after the disconnection, mustn't be repaired.
Fuses for housing and similar installations
In practice we use series marked DII (6 A, 10 A, 13 A, 16 A, 20 A,
25 A) and DIII (35 A, 50 A, 63 A).
Ordinarily we can encounter fuses with thread E27 (Edison) up to
25 A and E33 (Goliáš) from 35 A. Normalized colors are: 2 A pink, 4 A
brown, 6 A green, 10 A red, 13 A black, 16 A grey, 20 A blue, 25 A
yellow, 35 A black, 50 A white, 60 a 63 A brown(copper), 80 A silver,
100 A red, 125 A yellow.
Delimiting contact 10A
Fuse head E27
Fuse - fuse shell 6A E27
Cylindrical fuses
Cylindrical ceramic element has pressed metal caps on
edges as contacts. Both edges are the same. Current
ranges are distinguishable only by printing, color or shape
distinguishing aren‘t used. There are three dimensional
series: 10×38 mm for currents 0,5–25 A, 14×51 mm for
currents 2–50 A and 22×58 mm for currents 4–125 A.
Fuses are set into fuse switches.
Cylindrical
fuse
switches
10x38
Cylindrical fuse 100A
Power knife fuse
For securing performance-higher circuits (for example with
three-phase motors, whole houses) we use knife fuses.
Knife fuses are most often marked PN... Or NH... They are
manufactured in several dimensional series, which overlap
with their current range. Standard sizes are marked
PN000, PN00, PN1, PN2, PN3, PN4a.
Knife fuse 160A
Fuse bottom parts
Knife fuse 35A
Other fuses
Glass tube fuses are used for securing consumer
electronics devices. Their values range from
several tenths to several amperes.
Tube fuse
In cars and other vehicles there are usually plastic
fuses with knife contacts.
Vehicle knife fuses
Fuses are also divided into:
•fast - marked F
•Slow - marked T
Knife and cylindrical fuses are manufactured for different
operations
L/gG secure in whole current range against overload and
short-circuit.
aM fuses secure against the short-circuit, not secure against
overload. They are used for motor securing.
gR for semiconductor securing and gTr for securing
transformer are specialties rarely seen in common
environment.
gF1 for cable securing
What is a fuse?
How does the fuse work?
What kinds of fuses according to design do
you know?
What is the fuse color marking?
Pic no.1
Pic no.2
Pic no.3
Pic no.4
Pic no.5
Pic no. 6
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