I've salvaged a behemoth ammeter from a quarry pumping motor, can any one identify what kind it is, and if it's suitable for 12v DC ?
On the face are the markings" DC-AC25/100~ " it's a 100 amp machine, and is internally shunted.
????????????
Thanks.
Hmm, I think the only way is to try it out......but if its internally shunted I see no reason why it shouldn't work.
100 amps at 12 volts is 1200 watts. In order to get a reasonable deflection you could try a number of car headlamp bulbs, a 60 watt lamp will take 5 amps.Regards
Philip T-E
Motor Yes, your meter should work fine. The voltage of the system has no influence on the behaviour of an ammeter. As for what kind of meter, it is almost certainly a moving-iron instrument. These work on either AC or DC because the magnetic system has no inherent polarity, and measures the mean absolute value (unlike the popular D'Arsonval moving-coil type which is suitable for DC only). If you find the readings are out by a factor of 1.11 on DC, then the scale is calibrated for AC RMS and not DC / AC mean, but that would depend on its previous application. (This is because we normally quote RMS values for AC measurements, but the instrument actually measures the mean, and is scaled to indicate the RMS for a sine wave) You could fix that by tweaking the shunt. Lucien
Have something to add? Share your thoughts — no account required.
Ask the community — no account required