| ??? 08/01/05 13:11 Modified: 08/01/05 13:12 Read: times |
#98583 - Volt range Responding to: ???'s previous message |
Sun said:
6. The voltdrops across each bar I hace been told is in the region of millivolts. Hence the cct has to be have a very, very high accuracy. Im thinking accuracy and resolution should be in the odrer of tens or microvolts. This confuses me: You earlier told, that resistance of armature is 0.0148Ohm. Then applying 100A would give you a voltage drop of 100A x 0.0148Ohm = 1.48V. That isn't in the millivolt range! Also, if you apply a shunt resistor in series to winding of about 0.01Ohm, to measure the current that's actually flowing, you again get 1.0V. So, you have two voltage drops in the volt range, the one which provides you the actual flowing current and the other the winding resistance. Also, 100A into 0.0148Ohm gives about 150W power dissipation. That should not be much too high for a large DC motor. By the way, to what voltage does the welding supply collapse if you short circuit it by the winding of motor?? Kai |
