So, I scavenged this interesting looking motor from the local dump yard. The motor weighs around 4 oz. Measures 60mm in length, 42mm in diameter. The shaft is 5mm thick.

The motor comes with 3 wires. That is what is confusing me. It doesn't have any markings at all.

What motor would this be?

 

So, I scavenged this interesting looking motor from the local dump yard. The motor weighs around 4 oz. Measures 60mm in length, 42mm in diameter. The shaft is 5mm thick.

The motor comes with 3 wires. That is what is confusing me. It doesn't have any markings at all.

What motor would this be?

Based upon the 'impeller' (right-hand image) - the unit (as a whole) would seem to comprise some manner of fluid pump/fan -- The lead functions are likely Common, Power supply and a 'tachometry' (i.e. angular velocity) signal - Said assignments being ascertainable via careful experimentation/testing (barring data)...

Best regards and good luck!
HP

 

Based upon the 'impeller' (right-hand image) - the unit (as a whole) would seem to comprise some manner of fluid pump/fan -- The lead functions are likely Common, Power supply and a 'tachometry' (i.e. angular velocity) signal - Said assignments being ascertainable via careful experimentation/testing (barring data)...

Best regards and good luck!
HP

Thank you for your reply HP

"motor with 3 wires" on Google Images was leading me nowhere.

Never knew the technical term "impeller" . Was good enough to set me off on a scent. At least I now know that this impeller is of a design of almost the exact type as that used in car turbochargers.

But, the impeller's plastic is a little flimsy. So, I am guessing it would be for air rather than some fluid.

The motor's antecedents still eludes me.

Would have pried off the rear cap of the motor ( shall do if nothing comes up), but don't have narrow plier right now.

 

That appears to be a centrifugal pump. The fluid enters the impeller at the smaller end, and is accelerated as it flows out the larger diameter end.
... Difficult to say what the duty cycle is.
However, it is certainly for a liquid rather than a gas. A gas compressor would be much different, with greater flow surfaces.
... In order to use it as a pump, you would have to locate the casing for the impeller.

 

So, I am guessing it would be for air rather than some fluid.

Yebut - Gases are fluids - elasticity notwithstanding

...of almost the exact type as that used in car turbochargers.

IMO, based upon the description and images, it seems a bit 'light' for said service...

Would have pried off the rear cap of the motor ( shall do if nothing comes up), but don't have narrow plier right now.

Again, I assert that one of the leads is a 'tach' line -- Please be advised that determination of pin-out does not require 'butchering' of the motor

Best regards and again, good luck!
HP

 

However, it is certainly for a liquid rather than a gas. A gas compressor would be much different, with greater flow surfaces.

Not necessarily -- shrouded/ducted gas flow turbines often affect form-factors visually quite similar to liquid flow impellers... (A workaday example of which may be appreciated in the construction of many common household 'vacuum cleaners')

Best regards
HP

 

Just probed all the three leads of the motor for resistance and all pairs read at around 360 ohm. A 3-phase motor?

 

If the reading is the same across all three then it is most likely a 3 phase induction motor, but if you short the windings and try and spin it, it is a BLDC motor with P.M. field.
If you read the same for two winding's and double across the other two then it is a PSC 1ph induction motor and requires a cap to run.
Max.

 

If the reading is the same across all three then it is most likely a 3 phase induction motor, but if you short the windings and try and spin it, it is a BLDC motor with P.M. field.
If you read the same for two winding's and double across the other two then it is a PSC 1ph induction motor and requires a cap to run.
Max.

It indeed shows 360 ohms across all pairs. So, most likely it is a 3 phase motor.

Now, can't figure out what value should the start and run caps be?

 

It indeed shows 360 ohms across all pairs. So, most likely it is a 3 phase motor.

Now, can't figure out what value should the start and run caps be?

FWIW: A 'straight' (i.e. 'delta' or 'wye' connected) 3Φ motor requires no capacitor{s} when excited by a 3Φ supply...

That said, 360Ω seems a lot of resistance for even so small a motor -- I've got to wonder if, instead of a motor, said device is, rather, some manner of 'dynamo' as for measurement of fluid flow rate, etc...

Best regards
HP

 

FWIW: A 'straight' (i.e. 'delta' or 'wye' connected) 3Φ motor requires no capacitor when excited by a 3Φ supply...

I meant caps if I were to run it on a single 1Φ supply.

That said, 360Ω seems a lot of resistance for even so small a motor -- I've got to wonder if, instead of a motor, said device is, rather, some manner of 'dynamo' as for measurement of fluid flow rate, etc...

No clue as to what the coil resistances values are in motors.

I say this keeps getting more interesting.

 

No clue as to what the coil resistances values are in motors

Typically A fraction of an Ohm to a few Ohms -- I am, of course, referring to resistance (as opposed to inductive reactance)...

Best regards
HP

 

Typically A fraction of an Ohm to a few Ohms -- I am, of course, referring to resistance (as opposed to inductive reactance)...

Wow!! that's huge.

Umm, this is embarrassing. But, the DMM showed .364 in the 2K setting. Wouldn't that make it 364?

 

Wow!! that's huge.

Umm, the DMM showed .364 in the 2K setting. Wouldn't that make it 364?

Such is indeed typical of operation of 'manual-ranging' DMMs

Best regards
HP

 

Such is indeed typical of operation of 'manual-ranging' DMMs

So, HM, that's a wrong reading according to you?

 

So, HM, that's a wrong reading according to you?

Not necessarily 'wrong' -- merely very high for a 'rotating machine' designed as a motor...
The fact that all windings read the same argues against defect...

Best regards
HP

 

@kelaboy
Re: posts #13 and #14: To be clear - IMO you are correctly interpreting the DMM readings...

Best regards
HP

 

Not necessarily 'wrong' -- merely very high for a 'rotating machine' designed as a motor...
The fact that all windings read the same argues against defect...

A slight off-topic here. But, I can totally empathize with Watson ( of Sherlock Holmes fame ) right now.

 

I say pick two wires and give the thing a spin. If you get a voltage then it may be a generator of some sort. It COULD be some sort of ADG (Air Driven Generator) like similar things I've seen on aircraft. I've also seen ducted fans (3 phase) used to cool avionics. You might have something along that line as well. Keep in mind that in avionics (at least commercial and high end aircraft) they operate on 400 cycle, not 60 cycle.

 

I say pick two wires and give the thing a spin. If you get a voltage then it may be a generator of some sort. It COULD be some sort of ADG (Air Driven Generator) like similar things I've seen on aircraft. I've also seen ducted fans (3 phase) used to cool avionics. You might have something along that line as well. Keep in mind that in avionics (at least commercial and high end aircraft) they operate on 400 cycle, not 60 cycle.

Well we do think alike. A wild thought did occur to me that it might come from an aircraft's auxiliary turbine generator. But, that is almost unlikely considering where I am located right now. ( unless of course an ADG got shorn off a passing aircraft and landed in the dump yard.)

Did give the shaft a spin earlier with my fingers; the max and min voltages are around 4-14v