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Small tube fuse test results and test conditions has the very big relations, one of the most main has the following aspects:
1. The use of constant current power supply
In the evaluation of the fuse using constant current power supply than using stabilized voltage supply more accurate. If using a regulated power supply, load due to temperature rise will change the current flows through the fuse, the current changes the results measured fusing time is not accurate.
In the test the fuse fusing characteristics must be used in dc constant current power supply
In the test the fuse voltage drop should be used when the ac power supply, load current rating and obtain heat balance after reading
In the test the fuse nominal breaking capacity, to use ac power, and should be equipped with phase selector switch and safety protection device
In the test of the durability of the fuse, to use ac power, in the whole test process only allowed to have a break
2. The use of standard test device
Small tube fuse the fusing characteristics test must use a specific test equipment, including fuse jig, connecting wire diameter and length, the test instrument accuracy, etc.IEC and UL testing jig is different.
Laboratory environment temperature and other conditions stipulated according to the requirements of the safety standards.
3. Voltage drop and cold resistance
Generally speaking, the fuse cold resistance is basically a constant value, and voltage drop (thermal resistance) will with the rise and fall of temperature and the change, so in applications, the rated current when the voltage drop is important.
Rated current lower fuse resistance larger. In low voltage application conditions, the voltage drops will play a decisive role, and in some extreme cases, could cause not output the test (application) current.The fuse voltage drop and cold resistance can generally mutual conversion.
The fuse voltage drop applied alternating current (ac) test, the fuse of cold resistance can use dc test.
4. Breaking capacity
The fuse breaking capacity test takes a lot of power, general manufacturers, does not have the corresponding condition, force, the company built a very large test organization, have the ability to carry out all the fuse of all tests.
Ac sine wave in different phase of the current value is different, with energy and have very big difference, and fuse breaking capacity is in ac rated voltage, so and load circuit switching phase has the very big relations, IEC test requirements provisions: test circuit must be zero voltage phase after 300 c when switching.
5. Durability
IEC standard fuse of durability test to the six sample series up, on the whole test process, the only allowed once because accident caused by the interrupt, interrupt after finish the whole test continue to continuous.
6. Melting heat value and power
The fuse melting heat value and power is to choose the fuse a reference, no testing regulations.
Most of the fuse suppliers can provide the parameter, only strong, the company's products in the directory for almost every kind of fuse indicated the melting heat value parameter for users accurately choose to provide a complete set of reference data.
7. Tension and torsion
Tubular fuse requirements can withstand the 0.5 Kg tensile and no torque requirements.
Tensile resistance test method is to use the provisions of the special tools.
IEC standard regulations require will fuse into 150 c - 350 c in warm water for 2 hours last in business force test, for convenience, also can be in cold conditions.
8. Collimation degrees
The fuse end cap and tube body must be kept in the same axis, to ensure that the connection with good, test the fuse alignment of the provisions of the need to use special alignment gauge.
9. Mark
Small tube fuse the sign in general are in both ends of the copper cap with hard printed list out, its content includes:
The first end: manufacturers of trademark, such as red of REOMAX
；
All kinds of safety certification mark, such as:
The second end: fusing characteristic symbol:
F - represent fast fuse
T - representative slow fuse
M - on behalf of medium speed fuse
FF - representative express fuse
TT's representative, slow fuse
Rated current value:
More than 1 A with XX A said
1 A in the following XX mA said
Breaking capacity type:
L - represent low fault class
H - represent high marks off class
Rated voltage value:
1000 V, 500 V, 350 V, 250 V or 125 V, 63 V 32 V 12 V
There are some fuse with tube shell on the color ring sign, or tube body tag, in order to facilitate the identification of when installed in the circuit.
