What is the working principle of PMMC?
Definition: The instruments which use the permanent magnet for creating the stationary magnetic field between which the coil moves is known as the permanent magnet moving coil or PMMC instrument. It operates on the principle that the torque is exerted on the moving coil placed in the field of the permanent magnet.
Which principle is used in PMMC instrument?
The PMMC instrument working principle is based on the principle of the motor. When the current-carrying coil is positioned in the magnetic field produced by a permanent magnet, then a force is experienced by the coil and moves. This is called the D’Arsonval principle.
Which of the following is the main principle of PMMC ammeter?
The PMMC instrument working principle is when the torque is applied to the moving coil that is placed within the permanent magnet field, and then it gives a precise result for DC measurement.
What is the principle of operation of the moving coil meter?
Construction of Moving Coil Meter The moving coil instrument works on the principle of the DC motor (electrodynamic effect). It operates by the interaction of the magnetic field produced by a movable coil due to the flow of current with the field of a permanent magnet. It uses a coil for measuring voltage and current.
How do PMMC and moving instruments work?
The PMMC instrument working is similar to the motor working. The current through the coil when the instrument is connected to the circuit. When the current-carrying coil is placed in the magnetic field produced by a permanent magnet, then a mechanical torque acts on the coil and starts moving.
What is PMMC explain construction of PMMC?
The PMMC stands for permanent magnet moving coil and it is also called as D’Arsonval instruments. The PMMC works on the electromagnetic effect. A permanent magnet is used to produce magnetic flux and a coil that carries the current to be measured moves in this field.
What is PMMC and its application?
PMMC instruments are one of the simple and widely used onboard instruments, which can assist the electrical equipment with regular maintenance and measure the required quantities of the circuit. It is also known as Galvanometer or D’Alvanometer.
Why the PMMC instrument can be used for DC measurement only?
These types of instruments are only used for measuring the DC quantities as if we apply AC current to these type of instruments the direction of current will be reversed during negative half cycle and hence the direction of torque will also be reversed which gives average value of torque zero.
Which torque is used in PMMC meter movement?
The controlling torque is provided by two phosphorous bronze flat coiled helical springs. These springs serve as a flexible connection to the coil conductors. Damping is caused by the eddy current set up in the aluminium coil, which prevents the oscillation of the coil.
Why PMMC are widely used?
Advantages of PMMC Instruments The power consumption of the devices is very less. The PMMC instruments have high accuracy because of the high torque weight ratio. The single device measures the different range of voltage and current. This can be done by the use of multipliers and shunts.
How PMMC instrument can be used as ammeter and voltmeter?
A galvanometer may be used either as an ammeter (with the help of a low resistance) or as a voltmeter (with the help of a high series resistance). 2. By eliminating the control springs, the instrument can be used for measuring the quantity of electricity passing through the coil. This method is used for fluxmeter.
What are the features of PMMC meter?
It has a uniformly divided scale and can cover an arc of 270 degrees. The PMMC has a high torque to weight ratio. It can be modified as an ammeter or voltmeter with suitable resistance. It has efficient damping characteristics and is not affected by a stray magnetic field.
When PMMC instruments to be used as an voltmeter it is connected as?
A resistor of the same alloy is also placed in series with the coil to reduce errors due to temperature variation. 2) Voltmeter: When PMMC is used as a voltmeter, the coil is connected in series with high resistance. The rest of the function is the same as above.
How a PMMC meter can be used as voltmeter and ammeter?
When PMMC is used as a voltmeter, the coil is connected in series with high resistance. The rest of the function is the same as above. The same moving coil can be used as an ammeter or voltmeter to interchange the above arrangement.
What is the working principle of PMMC instrument?
The other moving coil instrument is a dynamometer type which can measure AC and DC work. The action of the permanent magnet moving coil (PMMC) instrument is based on the motoring principle.
What is a permanent magnet moving coil (PMMC) meter?
What is a Permanent Magnet Moving Coil (PMMC) Meter? What is a Permanent Magnet Moving Coil (PMMC)? A Permanent Magnet Moving Coil ( PMMC) meter – also known as a D’Arsonval meter or galvanometer – is an instrument that allows you to measure the current through a coil by observing the coil’s angular deflection in a uniform magnetic field.
What is the construction of a PMMC?
Figure 1 shows the basic construction of a PMMC instrument. A moving-coil instrument contains principally of a permanent magnet to offer a magnetic field and a small lightweight coil pivoted within the field.
What is the working principle of the electric meter?
This meter movement works on the motor principle and is a current-responding device. The deflection of the pointer is directly proportional to the amount of current passing through the coil. When direct current flows through the coil, the magnetic field so produced reacts with the field of the permanent magnet.