What do I need to test an old AC powered brushed motor? - Page 1
Forum section: electronics / beginners

author: mc
author_rank: Regular Contributor
timestamp: June 01, 2015, 12:40:54 pm
content: Hi guys/gals,this should be easy to find out, but in all honesty, I'm not sure what I actually need to google, so am struggling to fine the required information.In short, I have an old brushed motor, think electric drill, that I need to test. All I have is the motor/housing, but the switch/control electronics are missing. All I need to do, is to power up the motor a few times to take a few torque measurements, then bin the whole lot, but I'm struggling to figure out what exactly I need to do that.Full details are, it's an old 1980's electric impact driver that was used to actuate a power drawbar on an old CNC milling machine. The impact driver was stripped of it's original switch/electronics, and wired directly to a custom power drawbar controller for the impact gun that simply accepted signals to tighten/slacken. The original machine controller was removed long ago, so I have no idea what signals/power was even supplied to the power drawbar controller. The gun has 4 wires, 2 of which power the armature, and two that power the field coils.All I want to do, is power up the impact driver to see what it's maximum torque is that it tightens bolts to, and then replace it with an air impact gun. However I can't locate wiring diagrams for the specific controller fitted (I do have one for an older version), and I'd rather avoid having to reverse engineer the controller to work out something that should be reasonably simple.All I know is the original impact gun is 230V and 800W.

author: SeanB
author_rank: Super Contributor
timestamp: June 01, 2015, 05:08:04 pm
content: Wire armature and coils in series, and then for a test connect to 12VDC. That will turn the motor at low speed, and then you can set up the torque meter for around 30x that as a max when running at 230VAC. To change direction you simply reverse the connections to either the armature or the field winding.

author: mc
author_rank: Regular Contributor
timestamp: June 02, 2015, 12:29:30 pm
content: The problem with that, is I need to test this thing at full speed/power, due to the way the impact hammer mechanism works.I'm sure this must be a fairly simple thing, given the number of power tools that use this style of motor, but as I said, I'm not even sure what to google for. I'm currently thinking finding an old drill and stripping it for the switch/electronics may be the easiest approach.

author: G7PSK
author_rank: Super Contributor
timestamp: June 02, 2015, 03:11:19 pm
content: Get one of these dimmer/speed control plugs, less than a fiver.http://www.ebay.co.uk/itm/Plug-in-Dimmer-Switch-Adjustable-Control-for-your-Light-Lamp-13A-Socket-/351193135383?pt=LH_DefaultDomain_3&hash=item51c4bdf917

author: mc
author_rank: Regular Contributor
timestamp: June 02, 2015, 11:51:42 pm
content: Cheers for the replies guys.The penny finally dropped, and realised the term I needed was universal or series wound commutator motor. What was throwing me off, was the fact the armature and field wiring are totally different sizes, so I wrongly assumed there must be more to it than simply wiring them in series, and applying some power.