Moving-Iron Instrument

a measuring instrument whose operation is based on the interaction between a magnetic field that is proportional to the quantity to be measured and a core made of a ferromagnetic material. The main elements of a moving-iron instrument are a measuring circuit that converts the quantity to be measured into a DC or AC current and a measuring mechanism consisting of a moving-iron system (Figure 1).

An electric current in a field coil generates an electromagnetic field that pulls the core into the coil, thereby exerting, on a shaft, a torque that is proportional to the square of the current flowing through the coil. As a result of the action of a spring on the shaft, a countertorque is developed that is proportional to the angle of rotation of the shaft. When the torque and the countertorque interact, the shaft and an attached pointer are rotated through an angle that is proportional to the square of the quantity to be measured. When the torque and the countertorque are equal, the pointer comes to rest.

Figure 1. A moving-iron instrument: (1) coil, (2) core, (3) shaft, (4) pointer, (5) scale, (6) spring; (l) current

Moving-iron ammeters and voltmeters are manufactured, mainly for measurements in 50-hertz AC circuits. In a moving-iron ammeter, the field coil is connected in series to the circuit containing the current to be measured; in a moving-iron voltmeter, it is connected in parallel. Moving-iron measuring mechanisms are also used in ratio meters. The most widely used moving-iron instruments are switchboard instruments of classes 1.5 and 2.5, although instruments of class 0.5 and even of class 0.1 are manufactured. The latter instruments may be used for frequencies of up to 800 hertz.

REFERENCES

Elektricheskie izmereniia. Edited by E. G. Shramkov. Moscow, 1972.
Elektricheskie izmereniia, 14th ed. Edited by A. V. Fremke. Leningrad, 1973.

N. N. VOSTROKNUTOV

单词	moving-iron instrument
释义	Moving-Iron Instrument Moving-Iron Instrument a measuring instrument whose operation is based on the interaction between a magnetic field that is proportional to the quantity to be measured and a core made of a ferromagnetic material. The main elements of a moving-iron instrument are a measuring circuit that converts the quantity to be measured into a DC or AC current and a measuring mechanism consisting of a moving-iron system (Figure 1). An electric current in a field coil generates an electromagnetic field that pulls the core into the coil, thereby exerting, on a shaft, a torque that is proportional to the square of the current flowing through the coil. As a result of the action of a spring on the shaft, a countertorque is developed that is proportional to the angle of rotation of the shaft. When the torque and the countertorque interact, the shaft and an attached pointer are rotated through an angle that is proportional to the square of the quantity to be measured. When the torque and the countertorque are equal, the pointer comes to rest. Figure 1. A moving-iron instrument: (1) coil, (2) core, (3) shaft, (4) pointer, (5) scale, (6) spring; (l) current Moving-iron ammeters and voltmeters are manufactured, mainly for measurements in 50-hertz AC circuits. In a moving-iron ammeter, the field coil is connected in series to the circuit containing the current to be measured; in a moving-iron voltmeter, it is connected in parallel. Moving-iron measuring mechanisms are also used in ratio meters. The most widely used moving-iron instruments are switchboard instruments of classes 1.5 and 2.5, although instruments of class 0.5 and even of class 0.1 are manufactured. The latter instruments may be used for frequencies of up to 800 hertz. REFERENCES Elektricheskie izmereniia. Edited by E. G. Shramkov. Moscow, 1972. Elektricheskie izmereniia, 14th ed. Edited by A. V. Fremke. Leningrad, 1973. N. N. VOSTROKNUTOV
随便看	new york dental society new york department of corrections and community supervision new york department of environmental conservation new york department of environmental protection new york department of health new york department of labor new york department of motor vehicles new york department of transportation new york design architects, llp new york design center new york dessert cafe new york diabetes association new york diamond exchange new york diesel new york digital salon new york disaster counseling coalition new york disaster interfaith services new york district board new york district key club new york dita users group new york dock railway new york dollar new york dormitory authority new york downtown clown new york draft riot