Hi guys!
We've had a myriad of other breakdowns to attend too lately. The guy from tech support finally responded to the question this week (attached) and we got some time yesterday to try a couple things.
So the first thing was i brought in a phototach i had at home, the control max speed was set to 75% so max rpm for test was 45.75hz, the measured phototach rpm was 2733 rpm and 175A 400V as read on vfd display. Vfd display also read 2725 rpm.
Nameplate rpm calculation is 60hz=3585rpm so 45.75 hz = 76.25% * 3585=2733.56.
When i saw that my head went blank because i was so sure we were underpowering the magnetics of this motor causing slippage thus the thought to raise voltage to cure problem, in fact, if no other solutions were obtainable, i had in mind to install an orfice on intake and run it at a vacuum to reduce load. When i saw this, all those ideas vaporized.
So, it appears the reason motor temp climbs too much is because we are magnetically saturated and pushing current that isnt necessary to spin the mechanical load... (screw). Correct me if im wrong but if anything, we need to reduce voltage correct??
So Pete must be right about the wye choice, we looked on net and seemed like a 30% change by switching connection to a wye. We did so and fired it up. As it spun up, the current meter on vfd seemed to be wildly hunting to 170s then down and up. Not being able to hear with tons of other noise we hit the kill switch. We envisioned a situation where the vfd freq climb did not match the acceleration of the shaft under load which could cause a bad event. As yet its still connected as wye but locked out.
I plan to switch it back to delta next and verify nothing is hurt which i dont think it is.
So are we right in thinking the delta performance is real close just maybe a bit oversaturated? After all it ran for 120hrs. with subzero F° cooling. Maybe im just wierd for thinking winding temp should stay below 100C? Shouldnt there be more slippage than that?
I feel like if tech support werent so absent all this needs is a vfd tune which is a standard procedure for all large HP vfd setup...
I get their argument about motor should be identical to original and you wont have issue, still vfd tune is always done with new motor install regardless if oem or not.
I think the wye connection would be fine also with new vfd settings. Part of me wants to call Danfoss and get original software reload for vfd and do the normal setup an this would likely be running. Then im faced with wiring my own pressure control loop which im not crazy about modifying an oem machine...liabilities.
Sorry if i sound confused, Ha! I am.
(I meant to include what i wrote to tech support but it wasnt in photo i will try to add, it said something like. We need this machine running and if you wont give us lock codes, can you send a technician on site to make corrections? That was his response.)