What is Hot Wire Instrument? | The Definitive Guide

Hello friends, in today’s article we will see what a hot wire instrument is, why it is constructed, and what are its working methods. We are also going to talk about its advantages and disadvantages.

What is a Hot Wire Instrument?

A hot wire instrument device that uses the heat of a current to know its heat is known as a hot wire device. It works on the principle that the length of the wire increases due to the effect of current on it. Hotwire instrument is used for both AC and DC.

Construction of Hot Wire Instrument:

The construction is shown in the figure below. The current that is used for its measurement is passed through that platinum-iridium wire. This instrument uses 2 wires.


One platinum-iridium wire is tied between points A and B and the other wire is tied between the first wire and D points. And this second wire is connected to the spring at the S point with the help of silk thread from the middle.

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The function of Hot Wire Instruments:

When the current passes between points A and B it heats up and spreads. This causes it to sag. With the help of this wire spring, it returns to its original state. The contraction and expansion of this warp turn the pulley. Which causes the pointer to deflect. The spread of the warp is equal to the square of the RMS value of the current.


Advantages of Hot Wire Instruments:

The benefits of Hot Wire Instruments are as follows :

  • This instrument is used for both AC and DC power.
  • It has no magnetic field.
  • Its construction is simple and inexpensive.
  • Hot Wire Instruments shows the current RMS value.

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Disadvantages of Hot Wire Instruments:

The disadvantages of Hot Wire Instruments are as follows:

  • The platinum-iridium wire gives a slow response when heated.
  • This tool often has to adjust to zero position.
  • This instrument is found to be unbalanced due to hot and cold and the pulling of the wire.
  • Not strong enough to withstand overload and mechanical shock due to plain construction.
  • Hot Wire Instruments use more power.

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Andrew is a researcher and tech writer passionate about all things tech. He has written for many different publications and websites and has a wealth of knowledge to share.

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