Curt Harms
07-23-2006, 12:48 PM
Hi All
When I first got the Performax, I tripped the motor overload swich a few times, just couldn't tell how much of a load the motor was under. I believe that when one of these overloads protectors trip a number of times, they get weak and trip before the motor is really overloaded. I decided that one way to not overload the motor was to install an ammeter so I could monitor the load.
The ammeters that I found that were direct reading seemed like they might not stand up to repeated current surges from a motor/sanding drum combination starting, so how to keep the starting surge out of the Ammeter? An ammeter using a shunt setup might stand up to starting surges, but I wasn't that clear on how to use a shunt setup or where to find one for cheap. The schematic, such as it is, shows what I came up with. A motor rated toggle switch that when in one position routes current past the ammeter.
When in the other position, it routes current through the ammeter. I can't see any way for current to bypass the ammeter when the ammeter is selected. My procedure is to start with the toggle swtich in the ammeter bypass position, let the sander come up to speed, then switch the toggle to ammeter read position. I can't detect any lag or hesitancy in the sander when switching. I don't switch it while under load.
I also ran the output from the toggle switch/ammeter combination to a 20 amp. outlet mounted in the gray box. This way, I can plug any 115 volt device, i.e. router, saw or whatever and see what the amp draw is on the machine while in use. A harbor freight clamp-on meter would have been easier, but i thought that impractical for extended use.
One thing that sorta surprised me was that the Performax draws about 9-10 amps while idling, and the motor is rated to draw 13 amps. I would not have suspected a motor would draw 2/3 of it's rated amperage without doing anything useful. I did check the ammeter against a clamp-on unit and they were within 5% or less. The setup does work well. I can vary the feed speed to keep the ammeter right on 13 amps, and haven't tripped the overload since I rigged this up.
The parts involved are basic except for the ammeter. I found that on the auction site. The box, box connecters and power cord are from a borg. I had to go to an electrical supply house to find a suitable motor-rated toggle switch.
Comments and criticism are welcome. Trying to burn the house down?:eek:
Curt
When I first got the Performax, I tripped the motor overload swich a few times, just couldn't tell how much of a load the motor was under. I believe that when one of these overloads protectors trip a number of times, they get weak and trip before the motor is really overloaded. I decided that one way to not overload the motor was to install an ammeter so I could monitor the load.
The ammeters that I found that were direct reading seemed like they might not stand up to repeated current surges from a motor/sanding drum combination starting, so how to keep the starting surge out of the Ammeter? An ammeter using a shunt setup might stand up to starting surges, but I wasn't that clear on how to use a shunt setup or where to find one for cheap. The schematic, such as it is, shows what I came up with. A motor rated toggle switch that when in one position routes current past the ammeter.
When in the other position, it routes current through the ammeter. I can't see any way for current to bypass the ammeter when the ammeter is selected. My procedure is to start with the toggle swtich in the ammeter bypass position, let the sander come up to speed, then switch the toggle to ammeter read position. I can't detect any lag or hesitancy in the sander when switching. I don't switch it while under load.
I also ran the output from the toggle switch/ammeter combination to a 20 amp. outlet mounted in the gray box. This way, I can plug any 115 volt device, i.e. router, saw or whatever and see what the amp draw is on the machine while in use. A harbor freight clamp-on meter would have been easier, but i thought that impractical for extended use.
One thing that sorta surprised me was that the Performax draws about 9-10 amps while idling, and the motor is rated to draw 13 amps. I would not have suspected a motor would draw 2/3 of it's rated amperage without doing anything useful. I did check the ammeter against a clamp-on unit and they were within 5% or less. The setup does work well. I can vary the feed speed to keep the ammeter right on 13 amps, and haven't tripped the overload since I rigged this up.
The parts involved are basic except for the ammeter. I found that on the auction site. The box, box connecters and power cord are from a borg. I had to go to an electrical supply house to find a suitable motor-rated toggle switch.
Comments and criticism are welcome. Trying to burn the house down?:eek:
Curt