Finally, depending on the precision and repeatability needed in the application,
ammeter shunt resistors may need to be traceable to standards and require an annual schedule of recalibration and recertification.
The most common source of error in any current measurement lies in the fact that the
ammeter has a non-zero input resistance.
Verify monthly by checking with a clamp on amprobe at the starter that what the
ammeter is reading is accurate.
By adding a guard conductor between the conductor having voltage V on it and the sensitive input to the
ammeter, the current V/R flows to ground through the guard conductor and the
ammeter reads only the signal current [I.sub.S].
PID control, autotuning, softstart, RS485 or RS232-C computer interface, digital
ammeter with alarm, and run and standby setpoints.
The
Ammeter - This is the most overlooked troubleshooting device on the blast machine.
A typical test system for resistivity consists of a dc voltage source to provide the stimulus voltage, a series
ammeter to measure the stimulated current and a test fixture to connect the sample under test in series with source and the
ammeter.