Farkwar da ake kira aiki daga ammetar mai yin magana da ammetar mai yin magana da kyau na musamman
Takaitaccen Matar Moving Coil da Permanent Magnet Moving Coil (PMMC) Meters
Matar Moving Coil da Permanent Magnet Moving Coil (PMMC) meters suna cikin abubuwan electromechanical da ake amfani da su wajen bincike abubuwa masu karamin kwarewa, amma akwai farko a kan yadda ake gina su, yadda suke yi aiki, da kuma tushen ake amfani da su. Tana da haka bayanin mai karatu na biyu:
1. Kananan Gini
Moving Coil Meter
Magnetic Field Source: A cikin matar moving coil na gadi, an gina magnetic field ta a kan juyin current-carrying coils (field coils) da ke sauran moving coil. Waɗannan field coils suna haifar da current da ke faru a kan moving coil.
Moving Coil: An fuskantar moving coil a kan bayan field coils kuma ya faru current da za a bincika. Yana iya zama a kan pivot ko jewel bearing.
Damping: Damping ana ba shi da air friction ko eddy currents, wanda ke taimaka a kawo pointer zuwa yanayi a matsayin lokaci ba a nan deflection.
Permanent Magnet Moving Coil (PMMC) Meter
Magnetic Field Source: A cikin PMMC meter, an gina magnetic field ta a kan permanent magnet, wanda ke gina strong and stable magnetic field. Wannan ya tsarki a kwabta field coils na gargajiya.
Moving Coil: An fuskantar moving coil a kan gap na permanent magnet. Idan current ya faru a kan moving coil, ya jawabi da magnetic field, wanda ke taimaka a kawo coil zuwa rotation.
Damping: PMMC meters suna amfani da eddy current damping, inda small aluminum disk ko vane da ake fuskantar a kan moving coil ya yi rotation a kan magnetic field, wanda ke gina eddy currents wanda ke taimaka a damping.
2. Siffar Aiki
Moving Coil Meter
Operation: Matar moving coil ya yi aiki a kan siffar electromagnetic induction. Idan current ya faru a kan moving coil, ya gina magnetic field wanda ya jawabi da field produced by the field coils. Wannan jawabi ya gina torque wanda ya taimaka a kawo moving coil zuwa rotation. Deflection ta pointer ya kasance proportional to the current passing through the moving coil.
Torque Equation: Torque (T) da ake gina a cikin matar moving coil ya kasance:
idani B shine magnetic flux density, I shine current, L shine length of the coil, and d shine width of the coil.
Permanent Magnet Moving Coil (PMMC) Meter
Operation: Matar PMMC ya yi aiki a kan siffar motor effect. Idan current ya faru a kan moving coil, ya jawabi da strong and uniform magnetic field provided by the permanent magnet. Wannan jawabi ya gina torque wanda ya taimaka a kawo moving coil zuwa rotation. Deflection ta pointer ya kasance directly proportional to the current passing through the moving coil.
Torque Equation: Torque (T) da ake gina a cikin PMMC meter ya kasance:
idani B shine magnetic flux density, I shine current, N shine number of turns in the coil, and A shine area of the coil.
3. Abubuwan Adalci da Makafata
Moving Coil Meter
Abubuwan Adalci:
Za a iya bincike AC da DC currents, saboda magnetic field ya faru a kan current itself. Ba a buƙata permanent magnet, wanda zai iya rage cost and complexity.
Abubuwan Makafata:
Less accurate than PMMC meters saboda variations in the magnetic field strength.
Field coils suna consume power, wanda zai iya rage errors in low-power circuits.
Magnetic field ba ce uniform like in PMMC meters, wanda ke rage linear deflection.
Permanent Magnet Moving Coil (PMMC) Meter
Abubuwan Adalci:
Highly accurate and sensitive, especially for measuring DC currents.
Uniform magnetic field provided by the permanent magnet ensures linear deflection and high precision.
Low power consumption, as no external field coils are required.
Long life and reliability due to the absence of field coils.
Abubuwan Makafata:
Can only measure DC currents, as the direction of the magnetic field is fixed by the permanent magnet.
More expensive than moving coil meters due to the use of permanent magnets.
Sensitive to temperature changes, which can affect the magnetic properties of the permanent magnet.
4. Tushen Amfani
Moving Coil Meter
Tushen Amfani:
Used in general-purpose ammeters and voltmeters that need to measure both AC and DC currents.
Suitable for applications where cost and simplicity are important, and moderate accuracy is sufficient.
Often used in older or simpler instruments.
Permanent Magnet Moving Coil (PMMC) Meter
Tushen Amfani:
Widely used in precision DC measurements, such as in laboratory-grade instruments, multimeters, and panel meters.
Commonly found in digital multimeters (DMMs) for measuring DC voltage and current.
Used in industrial control systems, automotive instruments, and other applications requiring high accuracy and reliability.
5. Scale and Deflection
Moving Coil Meter
Scale: The scale of a moving coil meter is usually nonlinear, especially at higher deflections, due to the non-uniform magnetic field produced by the field coils.
Deflection: The deflection is proportional to the current, but the relationship may not be perfectly linear, especially at higher current levels.
Permanent Magnet Moving Coil (PMMC) Meter
Scale: The scale of a PMMC meter is linear, as the magnetic field is uniform and does not change with the position of the moving coil.
Deflection: The deflection is directly proportional to the current, making it easier to read and interpret.
6. Temperature Sensitivity
Moving Coil Meter
Temperature Sensitivity: Matar moving coil ba ce sensitive to temperature changes saboda magnetic field ya faru a kan current itself, rather than a permanent magnet.
Permanent Magnet Moving Coil (PMMC) Meter
Temperature Sensitivity: PMMC meters suna da sensitivity to temperature changes, saboda magnetic properties of the permanent magnet can vary with temperature. Amma, modern PMMC meters suna da temperature compensation to mitigate this effect.
Summary
Moving Coil Meter: Uses current-carrying field coils to generate the magnetic field, can measure both AC and DC currents, but is less accurate and has a nonlinear scale. It is suitable for general-purpose applications where moderate accuracy is acceptable.
Permanent Magnet Moving Coil (PMMC) Meter: Uses a permanent magnet to provide a strong and uniform magnetic field, can only measure DC currents, but offers high accuracy, linearity, and sensitivity. It is widely used in precision measurement applications.
