What value does a PMMC instrument read?
PMMC instruments (i.e. D’Arsonval meters) are only used for measuring the Direct Current (DC) current. If we were to use Alternating Current (AC) current, the direction of current will be reversed during the negative half cycle, and hence the direction of torque will also be reversed.
What will happen to a PMMC instrument if AC supply is given to it?
PMMC instrumentsinstruments uses two stationary permanent magnets to produce the deflecting toque. If was apply ac, the direction of current is reversed every half cycle and hence the net torque will be zero, so the pointer of the PMMC will not move.
How a PMMC meter movement can be used to measure resistance?
The ohmmeter is used to measure the resistance of the electric circuit by applying a voltage to resistance with the help of a battery. A galvanometer is used to determine the flow of current through the resistance.
When PMMC instrument is to be used as a voltmeter an external high resistance is called as?
PMMC Instrument MCQ Question 8 Detailed Solution The range of this instrument, when used as a voltmeter, can be extended or multiplied by using a high non-inductive resistance R connected in series with it, as shown in the given figure. This series resistance is known as a multiplier when used in dc circuits.
What do you mean by PMMC explain in brief?
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.
Why does PMMC measure DC?
The moving iron instrument is used for measuring both the direct and alternating current whereas the moving coil is used for the DC measurement. Because they PMMC are polarity sensitive. Meant to be used for DC only.
Why is PMMC not used in AC?
The reason you can’t use a PMMC with AC is because a PMMC, since it’s a moving mass, cant measure the instantaneous current, but rather measures the average current. The average current of an AC waveform is, of course, 0, so your meter will just read 0 the whole time.
What is PMMC type instrument?
What does PMMC stand for?
PMMC
| Acronym | Definition |
|---|---|
| PMMC | Profesinio Mokymo Metodikos Centras (Lithuanian: Methodological Center for Vocational Training) |
| PMMC | Providence Medford Medical Center (est. 1911; Medford, OR) |
| PMMC | Provena Mercy Medical Center (Aurora, IL) |
| PMMC | Permanent Magnet Moving Coil |
What is PMMC instrument principle?
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 principle is used by PMMC instrument?
What is the use of PMMC?
PMMC instruments are only used for measuring the DC quantities and it gives the average of value of the quantity being measured. If we apply AC current to these types of instruments, the direction of current will be reversed during negative half cycle.
How to increase the range of a PMMC instrument?
Multiplying power, The range of PMMC instrument, when used as a voltmeter, can be increased by using a high resistance in series with it. For measuring higher voltages, a high resistance is connected in series with the instrument to limit the current in the coil to a safe value.
How is the weight of a DC PMMC instrument counterbalanced?
The weight of the instrument is normally counterbalanced by the weights situated diametrically opposite and rigidly connected to it. The scale markings of the basic DC PMMC instruments are usually linearly spaced as the deflecting torque and hence the pointer deflection is directly proportional to the current passing through the coil.
What are the scale markings of a PMMC instrument?
The scale markings of the basic DC PMMC instruments are usually linearly spaced as the deflecting torque and hence the pointer deflection is directly proportional to the current passing through the coil. In a practical PMMC instrument, a Y shaped member is attached to the fixed end of the front control spring.
How does PMMC work with AC current?
PMMC instrumentsinstruments uses two stationary permanent magnets to produce the deflecting toque. If was apply ac, the direction of current is reversed every half cycle and hence the net torque will be zero, so the pointer of the PMMC will not move.