Category: Ammeters

Measurements of very Large Currents by Thermocouples

Measurements of very Large Currents by Thermocouples: Measurements of very Large Currents by Thermocouples – Thermocouples instruments with heaters large enough to carry very large currents may have an excessive skin effect. Ordinary shunts cannot be used because the shunting ratio will be affected by the relative inductance and resistance, resulting in a frequency effect. […]

Effect of Frequency Calibration

Effect of Frequency Calibration: The Effect of Frequency Calibration arises because of various factors such as: Skin effect Non uniform distribution of current along the heater wires Spurious capacitive currents Skin Effect The skin effect causes a higher reading at higher frequencies, especially if the heater wire is small. A low current instrument with a […]

Thermocouple Definition

Thermocouple Definition: Thermocouple Definition consists of a junction of two dissimilar wires, so chosen that a voltage is generated by heating the junction. The output of a thermocouple is delivered to a sensitive dc microammeter. (Calibration is made with dc or with a low frequency, such as 50 cycles, and applies for all frequencies for […]

DC Ammeter

DC Ammeter: DC Ammeter – The PMMC galvanometer constitutes the basic movement of a dc ammeter. Since the coil winding of a basic movement is small and light, it can carry only very small currents. When large currents are to be measured, it is necessary to bypass a major part of the current through a […]