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.
What is the damping used in a 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 are the benefits and drawbacks of hot wire instruments?
The following are the advantage 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.
What is the scale of hot wire instrument?
Exercise :: Measurements and Instrumentation – Section 3
| 14. | The scale of hot wire ammeter is |
|---|---|
| A. linear B. non-linear C. cramped D. absolute linear Answer: Option B Explanation: Since deflecting torque ∞ I2, scale is non-linear. Workspace Report errors Name : Email: View Answer Discuss |
What does hot wire ammeter measure?
current
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.
Can a hot wire ammeter measure DC?
Answer (c) both A.C. and D.C.
Why do we use hot wire instruments?
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 hot wire made of?
A Hot Wire Foam Cutter is a electrical tool used to cut polystyrene (EPS, XPS) foams and similar materials. The device consists of a thin, taut cutting wire, often made of NiChrome, Titanium, Stainless steel, or a thicker wire preformed into a desired shape, which is heated via electrical resistance to appr.
What is disadvantage of hot wire anemometer?
Drawbacks of a Hot-wire An inaccurate hot-wire anemometer can result in insufficient or even opposite pressurization of a room.
Which instrument is an example of an integrating instrument?
The energy meter, watt-hour meter and the energy meter are the examples of integrating instrument.
What is an analogue ammeter?
Analog ammeters, also known as current meters, are metered instruments that measure current flow in amperes. Current levels are displayed on a dial, usually with a moving pointer or needle made of a soft iron. This type of ammeter is called a shunt.
Can hot wire ammeter measures AC or DC?
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 is the purpose of a 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. The hot wire instrument is used for both the AC and DC current. The construction of the hot-wire instruments is shown in the figure below.
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.
What are the disadvantages of a hot wire instrument?
The following are the disadvantages of the hot-wire instrument. The Hot Wire instrument gives the slow response. The instability occurs in the instruments because of the stretching of the wire. The instrument consumes more power.
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.