strange encoder on SEW motor

rpoet

Member
Join Date
Jun 2008
Location
New York, NY
Posts
536
In 20+ years working with motors, I've never come across what showed up at the shop today. (photo attached) We ordered a set of small (1/3Hp) induction motors from SEW Eurodrive for a project, and they came with these strange "remoted" encoders. I'm working remotely so I'm not there right now; I'm trying to help my shop tech figure these things out.

We were expecting to get motors with "standard" encoders mounted to the NDE of the motor / fan shroud. Instead, we got what looks like the body of the encoder on the green lead. What gives? I'll check with SEW on Monday, but swapping the encoders probably isn't an option given SEW's current lead times.

What is this encoder topology? Is the green cable fiber optic, with the electronics "remoted?"


Thanks,

rpoet

20200515_141554sm.jpeg
 
If you can provide the SO # I can look it up and maybe find a manual. SEW usually has great resources with their PT PILOT.
 
Interesting ! Get that shroud off of there and see what's on the tailshaft.

I did a project with a dozen 1/4 HP SEW gearmotors like that last year and one of them gave me fits for months until I discovered the tailshaft mounting screw was loose and the encoder was slipping on the shaft.

Ours were what you expected; a tailshaft mounted encoder with an antirotation clip and a D-shell for the A-quad-B encoder connections.
 
I've seen a similar concept before in small DC motors where you get the encoder built into the motor, but never something on an industrial size before.


I wonder how the encoder really looks like and how it's attached.
 
As the servo controller would have to know what phase the motor is on the encoder would have to be mounted on the motor securely.

What is connected to the green cable might NOT be THE encoder for the motor, maybe it is an external feedback from the powered unit for RPM or FPM/MPM feedback after the gearbox. But with the green cable so short it doesn't look like it would reach past the gearbox it might be something else.

I would like to see more photos of the 'encoder' close up and a few angles.
 
I just searched the SEW website and for F Series (the Snuggler) motors it does show an optional externally mounted motor encoder. Not mentioned is how or where to mount it.
 
JRW: that's the DB15 / terminal connector SEW uses, and we had on all of our 1/4 HP motors. But it fit directly on the encoder, underneath the fan shroud.

So maybe that green cable is just a way to extend the encoder connection to get an even lower profile connector, or to make a quick-disconnect for which you don't have to remove the fan shroud.

On the project I used those on, we found a damaged encoder cable, and were very surprised, since they're hard to get to and our technicians has not been to site for months.

The explanation involved a privately catered party, and acrobats.
 
I have seen something like these before. The early versions used a sensor picking up embedded targets in the fan. Different fans were used to give different pulses per revolution. The later versions use a common fan and has the settings module in the remote box.
 

Thanks, Liam. I'm pretty sure that's what it is. We had to order something other than our "normal encoder" option due to lead times from SEW. I'm stopping by the shop tomorrow afternoon (when no one else is there) to make sure.

The encoder body that isn't an encoder is what threw me a bit. I guess if you're already making encoder bodies, it's cheaper to just modify what you already have on the shelf. I'll report back tomorrow after I have a look.

Thanks!


-rpoet
 
It's exactly what Liam thought it was; the thing that looks like the encoder body but isn't is designed to slot into the motor end bell sheetmetal.

What a goofy design; it still has a "normal" encoder internally, so there's not really any space savings lengthwise.

Most importantly though, the shop is no longer flummoxed, and it's up and working.


Thanks!

-rpoet
 
I see Liams pic
I still don’t get it. So what is in the silver terminal box looking thing? At the end of the cable

Sorry for the delay. I just got a picture of the installed connector body. The potato-like quality is because this site doesn't allow pictures larger than 300k in size.

The connector body slides into the slot in the fan shroud. No idea why it's made this way, but this was the option that was available from SEW in the time-frame we had.



-rpoet

IMG_0933sm.jpg
 

Similar Topics

Our CNC machine's spindle has a speed feedback encoder connected to it via a belt. The feedback rpm is displayed on the operator screen. When we...
Replies
4
Views
2,152
Hello all, I am facing an issue with my Commander SK that I cannot solve on my own, I am struggling on it since several days :confused: The...
Replies
9
Views
997
Hi. I'm doing an upgrade of an old 1400e to a new panel view plus 7 standard using ftv studio v 12,which will be communicating to a slc 5/04 via...
Replies
15
Views
2,559
Can someone explain the jumper between the elements? Does it do anything? See attached jpeg.
Replies
4
Views
667
We have an OPC server getting data from a Compactlogix PLC. The PLC also communicates with a Panelview and a couple VFDs via Ethernet/IP...
Replies
3
Views
1,148
Back
Top Bottom