Eddy Current Drive Issues

Question

Eddy Current Drive Issues

AllisonTT (Civil/Environmental)

(OP)

14 Feb 22 20:34

Good day, I work at a Wastewater Treatment Plant (WWTP) where we have 3-25HP Induction motors equipped with eddy current drives on vertical centrifugal solids handling pumps. See motor specs below this post. One motor is starting but there is no output.. pump shaft is not turning until motor is switched off, then it turns slowly and comes to a stop. The second motor is starting but there is no variation in pump speed/output even when the clutch coil is disconnected. Can anyone shed some light on why this may be happening and what troubleshooting measures we can use to find and resolve the problem?

Hoping to hear from you soon.

Variable Speed Drive:
Model AT-320258-0190
Min. RPM 50
H.P 25
Volts D.C 90
Ohms @ 20oC 20.8
Amps Hot 3.46
Max. RPM 805
H.P Diss. 45

INDUCTION MOTOR:
Model 040-092600-0252
Design B
Frame 324TDZ
Hertz 60
Insulation Class B
R.P.M 870
H.P 25
Volts 460
Ohms 20.8
Amps 41
Service Factor 1.15
Code G
Type TEFC
Frame 3
C Max Ambient 40

EdStainless (Materials) · Answer 1 · 2022-02-14 21:00:11

Sounds like the controls for your EC drives are bad.
You should be able to take some basic measurements and see if they are energizing and changing with input variations.
Reach out to someone who supplies and services these.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

FacEngrPE (Mechanical) · Answer 2 · 2022-02-14 23:12:41

I concur with Ed. about basic troubleshooting, your problem could be as simple as servicing the brushes for the rotating field. Your O&M manual will provide some guidance.
If you do not have one, this Dynamatic manual has the basic information https://www.dynamatic.com/wp-content/uploads/2018/...

AllisonTT (Civil/Environmental) · Answer 3 · 2022-02-15 15:07:39

Thanks guys. Found the AT Series Manual at Dynamatic.com. We are troubleshooting the control system first. Will let you know how things turn out.

dArsonval (Electrical) · Answer 4 · 2022-02-16 11:54:52

The OP states, "...vertical centrifugal solids handling pumps..."
It's unclear to the reader if the Eddy Current units are also mounted vertically.
Assuming they are, page 24 in the AT line PDF in the Final Mounting paragraph reads; "...make sure unit is level..."

PDF Reference: https://www.dynamatic.com/wp-content/uploads/2019/...

Not saying the units cannot be mounted vertically, "but" having worked on quite a few of these beasts before most of them disappeared,
I never came across one mounted in a vertical arrangement.

Most of these units have cylindrical roller bearings in them which restricts their mounting to a traditional horizontal arrangement.

Larger Electric Machinery eddy current drives... rated in many hundreds of horsepower are constructed specifically for vertical mounting... so there are vertical units out there.

John

salmanshu322 (Electrical) · Answer 5 · 2022-02-16 16:19:11

problem is with EC drivers or it is mounted vertically, it should be rated in hundred od horse power

AllisonTT (Civil/Environmental) · Answer 6 · 2022-02-21 04:42:59

The eddy current drives are vertically mounted but they were specially modified for this application. Got onto Dynamatic. They were helpful but we haven't resolved the problem yet.

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Eddy Current Drive Issues