Why tungsten is not used as a fuse cord?
Tungsten has melting point temperature it has almost 6192 degree Fahrenheit . The fuse wire should be able to melt at a relatively low temperature. However the tungsten can be used as a fuse in certain situations where high currents are required if you want to use something that does not take up much space and the fuse cord is made of silver, or copper lined with other metals.
So that the properties of tungsten –
- High melting point (6192 degrees Fahrenheit )
- High corrosion resistance
- High temperature resistance
- Lowest thermal expansion
- Inactive to react with other gases.
However this properties disable it for use as a fuse due.
Being a fuse wire the wire must have the following property which are as below
- Must be of low melting point
- Low ohmic loss
- High conductivity (or low resistivity)
- Low cost and
- Free from detraction.
Elements such as lead, lead, silver, copper and aluminum are used as fuse cables because they will melt if current in the circuit fluctuates and runs above 5a at certain circuits and 15a.If tungsten is used, it will not melt if the current rises above 15a, and it will fail to secure appliances such as a refrigerator, etc. which will ultimately cause damage to appliances and other circuit elements.
The fuse wire needs to melt at a sufficiently low temperature that’s why the metals like lead / tin alloys are usually used.The fuse cord should have a low melting point so when the current level rises above a certain level heats up the fuse wire and the wire melts and saves our equipment.Now if the tungsten is used in the fuse cable the tungsten will not melt because a large (very large) current is needed to melt it and the high current will continue through the fuse breaking the equipment.
