The Electrodynamic ammeter is used for measuring the intensity of the electric current running into a conductor’s section. This instrument is mainly characterized by four basic parameters: accuracy rate, range, resolution and insulation voltage.
INSIGHTS
The ammeter falls into the category of electrodynamic instruments, – all equipped with two coils– that can be connected either in series or in parallel.
Nel caso di collegamento in serie, visto che nella bobina mobile la corrente viene portata dalle molle antagoniste, la portata dell’amperometro è di pochi milliampere. Con correnti maggiori, l’amperometro si distruggerebbe. Le correnti che attraversano le due bobine sono ovviamente in fase tra loro.
If higher currents have to be measured by the ammeter, the two coils must be connected in parallel.
The electrodynamic ammeters are sensitive to temperature variations: to minimize these effects, an appropriate resistor of manganin (an alloy of copper, manganese and nichel) is connected in series to each coil.
A well-built ammeter is insensitive to the electric current frequency, since the two currents flowing in the coils – even if the two circuits are in parallel – can be co- phased
Tale strumento può essere utilizzato sia per correnti continue sia per correnti alternate ed è in grado di misurare il valore efficace della corrente anche se la corrente stessa contiene armoniche che ne modificano la forma dell’onda.
