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What is this odd Siemens 125v 3ph motor for?
- Thread starter tomjelly
- Start date
- Replies 18
- Views 2,412
Monarchist
Diamond
- Joined
- Oct 2, 2012
- Location
- Sol, Terra
If that is what you "ended up with", I'm afraid to ask what you started with..
Circulating pump or condensate pump, maybe? Dunno. But I have a VFD that could suit them. 120 V not 240 V.
TheHeavyMetal
Plastic
- Joined
- Aug 9, 2017
Possible blower motors
Monarchist
Diamond
- Joined
- Oct 2, 2012
- Location
- Sol, Terra
Could was - the RPM suits.
With the V/hz data on them, and a frequency range, they are clearly intended for use with a VFD. But the numbers that look like a date (1-25-1964) would indicate, if they ARE a date, a very old application, and the 150W power level is tiny for most machinery or even blower applications. Possibly a tape drive motor, feed motor, could be a pump, blower, etc, Anything requiring only a low power, but variable speed. The shaft type may be a clue.
Unless someone recognizes the motor, probably no way to know for sure.
Unless someone recognizes the motor, probably no way to know for sure.
That looks like laser engraved plate to me and in that case it is not from 1964
IEC80 standard is also most probably later invention (looks to be IEC80 B5 flange mount)
Normal 380v VFD is just about right for these @9000rpm, maybe that is a clue about normal operating rpm.
Oh, I'm surely not claiming anything about the date, because, yes, it DOES look laser, with the discoloration around all the letters..... And you forgot to mention that the "date-like number" is NOT in standard European format, but that is a German motor..
But that does not change the low power, and speed range info. The max current also.... makes it look "AC servo", but the power seems very weak for that. Interesting.
In that case, it may be for a take-up spool. Little power needed, but variable speed would be required to "follow the dancer" and maintain takeup of fiber or spun thread. There are other similar applications in plastic extruding operations for fiber or sheet.
Jraef
Titanium
- Joined
- Aug 10, 2004
- Location
- San Francisco Bay Area
In a typical EU based system, that rating allows you to run that motor up to 150Hz at 380V without losing torque. At 230V you could run it up to 92Hz and at 460V you could run that up to 184Hz, all without losing its rated torque. Think spindles.
So the max voltage is called out by the frequency range and 2,5v/hz notation on the tag? My technical vfd knowledge is limited but I thought they varied frequency only, or do they all increase v w/hz (or is the v increase a result of the increasing hz)?
Yes, and yes.
Jraef
Titanium
- Joined
- Aug 10, 2004
- Location
- San Francisco Bay Area
A VFD will vary the voltage and frequency together, in fact it MUST, because that's what determines the motor torque. The caveat however is that it can only DECREASE the voltage given to it. So if, in your machine design, you need a direct drive AC spindle motor with a speed higher than 3600RPM (the speed of a 2 pole motor), the only way to get that is to use a higher frequency than 60Hz. So for the VFD to be able to vary the frequency and voltage together at the correct ratio for the motor, you have to design the motor to accept a V/Hz ratio that fits your available power source. So in this case they obviously needed to run that (in 50Hz world) faster than 3000 RPM, so they designed the motor windings as a lower voltage, then allow the VFD to give it a higher voltage so that it can run it faster.
Well.. not the "only" way.. you can run it also with "reduced" voltage but your torque will suffer.
Monarchist
Diamond
- Joined
- Oct 2, 2012
- Location
- Sol, Terra
"Torque".... has been suffering.. ever since AC was invented..
T Rex - Dinosaur Current, bares bloody teeth, thunders ponderously off, stage left, shaking an AC motor like a mastiff on a rat..
Jraef
Titanium
- Joined
- Aug 10, 2004
- Location
- San Francisco Bay Area
Right...
You can START it with reduced voltage, but running it that way continuously will cause the torque to drop by the SQUARE of the voltage change; i.e. at 1/2 voltage, the motor produces 1/4 of it's rated peak torque. So unless the load torque is reduced by that amount or more, it causes the motor to have higher slip and pull more current, generally leading to it burning up. Other than that, no problem...myself said:
Is that not an indirect effect?
In the motor, the voltage and frequency affect the motor current. But it is CURRENT that affects torque, since CURRENT affects the magnetic fields that produce the torque.
It might be better to say that the voltage affects POWER available, since the effect of keeping the V/Hz the same (with VFD) is to keep the motor current the same, and hence the torque. (constant torque region)
You can look at it as A: same torque, lower speed >> lower power out , or B: Same current, lower voltage >> lower power input and so lower power out
Obviously at some point the resistances limit current below the amount that the torque would require.
And at high frequencies (speeds) the V/Hz drops, causing the current (and torque) to reduce as well (constant HP region)
In the motor, the voltage and frequency affect the motor current. But it is CURRENT that affects torque, since CURRENT affects the magnetic fields that produce the torque.
It might be better to say that the voltage affects POWER available, since the effect of keeping the V/Hz the same (with VFD) is to keep the motor current the same, and hence the torque. (constant torque region)
You can look at it as A: same torque, lower speed >> lower power out , or B: Same current, lower voltage >> lower power input and so lower power out
Obviously at some point the resistances limit current below the amount that the torque would require.
And at high frequencies (speeds) the V/Hz drops, causing the current (and torque) to reduce as well (constant HP region)
