DC Motor Failed to run on load
DC Motor Failed to run on load
(OP)
Hello,
Im using DC motor to run the conveyor but suddenly the armature shows high current 130 A for 30 V power and the speed cant increase anymore. The motor power stated in the name plate is 93.8 KW, Armature voltage is 453 V and Armature ampere is 225 A. The motor can run free load after disconnected from the load but fail to run on load. We have checked the field coil, armature coil and the brushes . The are no insulation damaged since it can be run free load.
What are the possible causes to the motor that fail to run on load? Is it because not strong magnetism or another mechanical failure?
Im using DC motor to run the conveyor but suddenly the armature shows high current 130 A for 30 V power and the speed cant increase anymore. The motor power stated in the name plate is 93.8 KW, Armature voltage is 453 V and Armature ampere is 225 A. The motor can run free load after disconnected from the load but fail to run on load. We have checked the field coil, armature coil and the brushes . The are no insulation damaged since it can be run free load.
What are the possible causes to the motor that fail to run on load? Is it because not strong magnetism or another mechanical failure?





RE: DC Motor Failed to run on load
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: DC Motor Failed to run on load
RE: DC Motor Failed to run on load
rasevskii
RE: DC Motor Failed to run on load
Is this an existing installation that worked before and now does not?= Then something may be jammed up in the conveyor, and the motor cannot break it away. The current limit in the drive may be correctly limiting the armature amps according to its original settings (at commissioning) but now this current limit is too low to break away the load.
Do not increase the settings beyond the original ones to resolve the problem, if it is mechanical. You may damage the motor beyond easy repair (flashover or burned commutator).
I am assuming (never assume...)that this is an existing installation, not a new one. Pls elaborate.
rasevskii
RE: DC Motor Failed to run on load
Actually this is an existing motor. The field coil is just rewound. The problem occur when we want to install back the DC motor to the machine. After all the connection are connected to the load, we did test run to the motor. We found out the armature did not rotate and the voltage only can run until 30V input voltage only instead or 453 V which is the actual armature voltage. The current of the armature increase to 130 Ampere while the voltage just only 30 V. We have swapped new motor to the same machine and the motor worked fine. Means there is no problem with the drive and the control panel setting. The motor can run with no load. What is the possible cause that can produce high amp to the armature?
RE: DC Motor Failed to run on load
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: DC Motor Failed to run on load
RE: DC Motor Failed to run on load
RE: DC Motor Failed to run on load
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: DC Motor Failed to run on load
P/S : Need advice because im new in this field.
RE: DC Motor Failed to run on load
I assume you mean 20volts/1000rpm (typical good tach) changed to 20v/7200rpm tach (typical crappy cheap tach).
If so, and you did not rescale the drive tach input, then of course this would account for your issue and explain why you only get 30v across armature.... I did not go back to look at details but if this was 230v armature with base speed of 1800rpm, the old tach scaling was near 30v at base speed of 1800rpm. Now you feed it only 10 volts at same 1800rpm so the output armature voltage will be 3x lower or down at 70-ish volts. this motor will not be happy and do stuff you said earlier like pull way too much amps trying to make up for the missing Kt!
rescale the tach input per manual.
RE: DC Motor Failed to run on load
Another thought; If this was a tach issue the motor would not run at full speed unloaded.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: DC Motor Failed to run on load
RE: DC Motor Failed to run on load
But even not knowing your new tach v/rpm rating you lucked out using it as you imperically proved it is also about 20v/krpm after all with your measurements. so ignore my suggestion of adjusting the tach input since you have now said it outputs virtually the same as the old one.
RE: DC Motor Failed to run on load