Why do we use hot wire instruments?
Advantages of the Hot Wire Instrument The instrument is used for both AC and DC measurement. It is a transfer-type instrument i.e, the calibration is same for both the AC and DC measurement. The hot wire instrument is free from the stray magnetic field. Their construction is very simple and cheap.
On which principle hot wire instruments work?
the thermal effect
The hot wire instrument is used for both the AC and DC current. Hotwire instrument works on the principle of the thermal effect, that the length of the wire increases because of the heating effect of the current flow through it.
What is a hot wire ammeter?
The hot wire ammeter is a device used to measure AC or DC current intensity based on the thermal expansion of a wire made of platinum and iridium alloy that is heated due to the flow of the electric current through it.
What are the benefits and drawbacks 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.
What is hot wire made of?
A Hot-wire Cutter is a tool which is used to cut polystyrene, Styrofoam and similar materials. The tool comprises of a thin, tight metal wire which is usually made up of nichrome or stainless steel. A thicker wire preformed into a specific shape is also used instead of the metal wire.
What is hot wire working?
Hot Wire. Hot wire is used as the initial power feed to a circuit. It carries the current from the power source to the outlet. Acting as the first instance of a circuit, they are always carrying electricity, meaning it is dangerous to touch a hot wire while there is a power source feeding it.
Which type of damping is used in hot wire?
Eddy current damping is the most efficient form of damping. It is very convenient to use in instruments where a metallic disc or a former and a permanent magnet already form part of the operating system. For these reasons this method is used in hot wire, moving coil and induction type instruments.
Why is hot wire ammeter is used?
Hint: Hot wire ammeter, as the name suggests, measures the value of current in a device based on the amount of heating it does. The heat it produces is measured with the help of a wire; more the heat, more the current.
How does a hot wire ammeter work?
Hot wire ammeter is based on the principle that when a current flows through a wire it gets heated. As a result the length of the wire increases. A platinum-iridium wire AB is fixed tightly between two fixed ends A and B. A spring is fixed at one end C and is permanently connected to a thin wire at the other end.
Which damping is used in hot wire instrument?
We usually provide eddy current damping in hot wire instrument. A very lightweight circular aluminum disc attached with the shaft of the pulley causes eddy current damping. The aluminum disc moves between the poles of a damping magnet as shown below.
What is a hot wire?
Hot wire is used as the initial power feed to a circuit. It carries the current from the power source to the outlet. Acting as the first instance of a circuit, they are always carrying electricity, meaning it is dangerous to touch a hot wire while there is a power source feeding it.
Why is it called hot wire?
The term hot wire refers to the wire with black or red insulation. This is the wire that causes current to flow between it and the neutral wire (or grounding wire if a fault occurs.
What is the definition of a hot wire instrument?
Definition: The instruments which use the heating effect of the current for knowing their magnitude such type of instrument is known as the hot wire instrument. It works on the principle that the length of the wire increases because of the heating effect of the current flow through it.
Why is the scale of a hot wire instrument not uniform?
As the angle of deflection is proportional to the square of the current, the scale of the instrument is not even or uniform. In hot wire instrument, a minimum time needs to be given to the instrument for heating up the platinum-iridium wire to the desired level. So the instrument does not give an instantaneous reading.
What causes a pulley on a hot wire instrument?
The pulley holds the pointer of the instrument. Whenever there is a current in the platinum-iridium wire, there will be an elongation of the wire due to the heating effect of the current passing through the wire. That elongation of the wire between A and B causes sag in the wire.
How is eddy current damping used in a hot wire instrument?
Damping : Generally eddy current damping is provided in hot wire instrument. A thin light aluminium disc is attached to the pulley such that it moves between the poles of permanent damping magnet ,M. 1. Such instruments can be used for both a.c and d.c. 2. There readings are independent of waveform and frequency. 3.