Bill Adamsen
04-08-2015, 4:57 PM
I have a larger Italian made Bandsaw that I was running for a long time (several hours?) continuously today and it seemed like the machine seemed to "get quieter." I don't have any sort of blade velocity gauge to reference, that would have helped. It did not seem to lose any power, though the job I did was not very demanding.
I popped the cover off the 3-phase load center and legs between the breaker and the saw were reading a steady voltage and current. But this baffles me. The voltage coming in to the RPC (single phase) is 243.7 volts between the legs ... 120v & 124v for each leg (L1 & L2) to ground. Unloaded (no tool on) the 3-phase made leg (T3) to each leg are the voltages... L1-T3=262, L2-T3=271 and L1-L2=243.9. Loaded (and by any of the operating machines) those drop to approximately L1-T3=240, L2-T3=252, L1-L2=242. All within a reasonably small percentage of each other. This is well within the range specified by the manufacturer.
The current on the Bandsaw was L1=4.7a, L2=11.4a and T3=10.2a. So while the voltages are normal, the current readings are baffling variable to me. I don't have a prior current recording to refer to. Should I be concerned about this? I guess I can go out and check the current readings on other tools running.
[update] Just checked two other machines with similar kilowatt motors and the amp draw is very close on both machines and within about 25% overall ... L1=9.4, L2=12.5 and T3=12.8. The variation on the bandsaw is 40%+. It could be connections ... will check tomorrow. Interestingly, nothing got hot on the motor or bearings today during work. It seemed to be running along smoothly. Too smoothly.
I popped the cover off the 3-phase load center and legs between the breaker and the saw were reading a steady voltage and current. But this baffles me. The voltage coming in to the RPC (single phase) is 243.7 volts between the legs ... 120v & 124v for each leg (L1 & L2) to ground. Unloaded (no tool on) the 3-phase made leg (T3) to each leg are the voltages... L1-T3=262, L2-T3=271 and L1-L2=243.9. Loaded (and by any of the operating machines) those drop to approximately L1-T3=240, L2-T3=252, L1-L2=242. All within a reasonably small percentage of each other. This is well within the range specified by the manufacturer.
The current on the Bandsaw was L1=4.7a, L2=11.4a and T3=10.2a. So while the voltages are normal, the current readings are baffling variable to me. I don't have a prior current recording to refer to. Should I be concerned about this? I guess I can go out and check the current readings on other tools running.
[update] Just checked two other machines with similar kilowatt motors and the amp draw is very close on both machines and within about 25% overall ... L1=9.4, L2=12.5 and T3=12.8. The variation on the bandsaw is 40%+. It could be connections ... will check tomorrow. Interestingly, nothing got hot on the motor or bearings today during work. It seemed to be running along smoothly. Too smoothly.