Experimetal Study on Electrical Short-circuit
Richard Lu
High temperature induced by electrial short-circuit may ignite th
e surrondings and finally cause a fire.
1. Introduction
Purpose of experimental study on electrical short-circuit and
analysis of the remarks:
Investigation of electrical fires
Understanding the mechanism to prevent related
electrical fires
1. Introduction
• Design a test rig to simulate the electrical sh
ort-circuit and reproduce the elestrical failu
re.• Analye the ignite character and remain rem
arks of the electrical short- circuit.• Provide essential data for fire related resear
ch.
1. Introduction
• 2.1 Test rig for simulating electrical short-circuit
motor
belt
contact plate
Contact plate and conta
ct arm driven by the m
otor-belt device move r
elative to one another.
Electrical short-circuit i
s reproduced while the l
ive line fasten to the co
ntact plate contacts.
2. Experiments
contact arm
• 2.2 Experimantal material - wires
a. Copper wires b. Aluminum wires coated with copper
2. Experiments
• 2.2 Experimantal material - power supply
12V lead-acid battery
2. Experiments
3. Schematic of the experiments
Direct current breaker Failure piont
36V DC power supply
• 4.1 Set up the test rig
4. Process of experiments
• 4.2 Fix the wires
4. Process of experiments
• 4.3 Control the test rig to simulate the electrical short-circuit
4. Process of experiments
• 4.4 Collect the remarks of the failure point
4. Process of experiments
• Short-circuit between copper wires shine blinding light and release a large
amount of heat which can melt the copper wire immediately.
5. Results of the experiments
5. Results of the experiments• Short-circuit between aluminum wires coated with copper is more fierce.
• More intense light and heat are generated. A mount of melting bead is spl
ashed and strong white smoke is generated after the short-circuit.
• Melting bead splashed during short-circuit between aluminum wires coated wit
h copper can ignite more distant combustible material, which is more dangerou
s.
5. Results of the experiments
• Frequently-used copper wires and aluminum wires coated with co
pper were chosn for the experiment.
• The melting point of copper and aluminum are following:
Material Melting point/℃ Ignite point/℃
Cu 1084 —
Al 660 —
Insulating material
PVC — 255 ~ 300
Rubber — 130
Silica gel — 350
PTFE 327 —
5. Results of the experiments
• 36V DC power supply was employed since it is safe for the ope
rating personnel. The electrical short-circuit occured under 36V
DC power supply condition can melt the wire material immedite
ly.
• If the 220V AC which is frequently-used in normal building is
used , the electrical short-circuit will release much more heat an
d the surrounding materials will be ignited much more easily.
5. Results of the experiments
• Signs of Short-circuit were found after the experments for both wires.
5. Results of the experiments
a. Copper wires b. Aluminum wires coated with copper
• Signs of Short-circuit are important evidence left in electric fire
scene.
• The remarks in this study were obtained under ambient
temperature.
However, remarks left in pratical fire scene are often obtained
under fire environment.The difference between them need to be
studied.
• The procedure introduced in this study can be used as a
standard preparation method for electrical short-circuit remar
ks.
5. Results of the experiments
A standard preparation method for electrical short-circuit
remarks is presented.
Short-circuit between copper wires may directly ignite the
insulating materials and induce a fire.
Short-circuit between aluminum wires coated with copper may
ignite the insulating materials and more distant combustible ma
terial, which are more likely to induce a fire.
6. Conclusion