Aiki da Turanci na Koyarwa ko PMMC Instrument

Takaitaccen

Abubuwa da take amfani da magneti mai zurfi don kawo shirya mai zurfi da ke tsakanin da yake zama kofin mai zurfi (PMMC) suna nufin. Sun yi aiki a harkokin da kofin mai zurfi ke tsakanin da shirya mai zurfi na magneti. PMMC sun bayar da natijoyin da suka daidai wajen bincike waɗannan karamin mafi yawa (DC).

Kudin PMMC Instrument

Kofin mai zurfi da magneti mai zurfi suna cikin abubuwan da suka da muhimmanci a cikin PMMC. Wannan shine bayanin tushen da ke cikin PMMC instrument.

Kofin Mai Zurfi

Kofin shine babban mutum da ke ciki da karamin mai zurfi wanda ya fi kofin yana gida a cikin shirya mai zurfi. Idan karamin mai zurfi ya fara kan kofin, yana haifar da kofin, wanda ya ba ta haka da tushen da ke ciki da karamin mai zurfi ko karamin mafi yawa. Kofin ana kafa a cikin babbar da ke ciki da aluminium. Wannan babbar yana haifar da shirya mai zurfi da ke ciki da karamin mai zurfi a cikin gasar da ke ciki da kutukan shirya. Kofin ana kasa da karamin mai zurfi da ke ciki da silk - covered copper wire a cikin kutukan shirya.

Magnet System

A cikin PMMC, magneti mai zurfi an amfani da ita don kawo shirya mai zurfi. Alcomax da Alnico suke amfani don kawo magneti mai zurfi saboda har da coercive force (coercive force yana haifar da magana na magneti). Duk da haka, wasu magneti suna da shirya mai zurfi da dama.

Control

A cikin PMMC, controlling torque an samun min fannonin springs. Wasu springs suna da phosphorous bronze da ke ciki da karamin mai zurfi. Springs suna da muhimmanci don kawo karamin mai zurfi a cikin kofin mai zurfi. Controlling torque suna da muhimmanci saboda ribbon suspension.

Damping

Damping torque an amfani don kawo kofin a cikin gasar da ke ciki. Wannan damping torque an samun min movement of the aluminium core as it moves between the poles of the permanent magnet.

Pointer & Scale

Pointer an kafa a cikin kofin mai zurfi. Yana nuna tushen da kofin ke ciki, da kuma tushen da ke ciki a cikin scale. Pointer an kafa a cikin karamin mai zurfi, wanda ya ba ta haka da tushen da ke ciki da karamin mai zurfi. A lokacin da parallax error yana faru, za a iya kawo karfin da take faru a cikin pointer blade.

Torque Equation for PMMC Instrument

Deflecting torque an samun min movement of the coil. Ana bayyana wannan equation.

• N – Number of turns of coil

• B – flux density in the air gap

• L, d – the vertical and horizontal length of the side

• I – current through the coil

Spring an samun restoring torque to the moving coil which is expressed as 

Where K = Spring constant.

For final deflection, 

By substituting the value of equation (1) and (3) we get,

Wannan equation yana nuna cewa deflecting torque yana da muhimmanci da karamin mai zurfi.

Errors in PMMC Instruments

A cikin PMMC, errors sun faru saboda ageing da temperature. Abubuwan da suka da muhimmanci a cikin instrument suna cikin magnet, spring, da kofin mai zurfi. Wannan shine bayanin types of errors:

1. Magnet

Heat da vibration sun kawo zuwa zuwa da takamantar magneti mai zurfi, da kuma kawo zuwa zuwa da magnetism. Magnet mai zurfi mai yawa yana kawo zuwa zuwa da tushen da kofin ke ciki.

2. Springs

Spring mai yawa yana haifar da tushen da kofin ke ciki. Saboda haka, idan karamin mai zurfi yana da ma'ana mai yawa, kofin yana haifar da tushen da ke ciki. Spring yana yawa saboda temperature; one - degree rise in temperature reduces the spring's lifespan by 0.004 percent.

3. Moving Coil

Idan range of the coil yana yawa saboda shunt, errors sun faru. Wannan shine saboda change in the coil resistance relative to the shunt resistance. Saboda kofin an kasa da karamin mai zurfi da ke ciki da Manganin, mismatch yana haifar da errors.

Don kawo karfin da take faru, ake kafa swamping resistance a cikin series with the moving coil. Swamping resistance shine resistor da low - temperature coefficient, wanda yana haifar da impact of temperature on the moving coil.

Advantages of PMMC Instruments

Wannan shine advantages of PMMC instruments:

• Scale of PMMC instruments yana da accuracy.

• Power consumption of these devices yana da ma'ana mai yawa.

• PMMC instruments suna da accuracy saboda high torque - to - weight ratio.

• A single device can measure different ranges of voltage and current by using multipliers and shunts.

• PMMC instruments use shelf - shielding magnets, which are beneficial for aerospace applications.

Disadvantages of PMMC Instruments

Wannan shine disadvantages of PMMC instruments:

• PMMC instruments suna da muhimmanci saboda direct current. Alternating current varies with time, and the rapid variation of current changes the torque of the coil. However, the pointer cannot follow the fast reversals and deflections of the torque, so it cannot be used for AC.

• Cost of PMMC instruments yana da ma'ana mai yawa saboda other moving - coil instruments.

• Moving coil itself provides electromagnetic damping. This electromagnetic damping opposes the motion of the coil as a result of the interaction between eddy currents and the magnetic field.