The Ammeter is a device used to determine the strength of alternating and direct current in an electrical circuit. Accordingly, the readings on the ammeter depend on the value of the current passing through it. The resistance of the ammeter must be less than the resistance of the load. Depending on the design features ammeters are: electromagnetic, electrodynamic, rectifier, magnetoelectric, ferrodynamic, thermoelectric.
- Electromagnetic . These ammeters are used to measure the current flowing in circuits. Respectively, constant or variable. Most of all it is used when it is necessary to measure the strength of an alternating current at 50 Hz. This is the industrial frequency. Consists of: measuring mechanism, scale.
- Magnetoelectric . They, as a rule, measure the strength of a direct current of small magnitude. Consists of: measuring magnetoelectric mechanism and scale.
- Electrodynamic . Measures AC and DC currents up to 200 Hz. This is an increased frequency. This device is very sensitive to external magnetic fields and overloads. They are used as control devices. Consists of: measuring electrodynamic mechanism, scale, coil. It can be connected in series or in parallel. Depends on how much current we want to measure.
- Thermoelectric . Measures high frequency alternating current. Consists of a magnetoelectric measuring mechanism with a transducer and a thermocouple welded to it. Passing through the heater, the current causes heating. It is detected by a thermocouple.
- Ferrodynamic . Very durable, reliable. Almost insensitive to magnetic fields. Consist of a ferrodynamic measuring mechanism. It is most used as an ammeter-recorder.
- Rectifiers . Measure the strength of alternating current with a frequency of up to 10 Hz. They consist of a magnetoelectric mechanism that is connected to a rectifier circuit.
