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Altivar 28 Inverter

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ChrisH17/05/2011 12:45:02
1023 forum posts
30 photos
I had an Altivar 8 inverter 'converting' 240V single phase into 240V three phase. It drove the 3 ph motor on my lathe via the lathe's forward-off-reverse switch and then the lathe's low speed-off-high speed switch. It was old and not really man enough for the job, but it worked. Until just over a week ago when it announced it had had enough, and died. The inverter was powered up to 50Hz by closing a switch on a logic input.
 
I replaced it with an Altivar 28 inverter, which is man enough for the job but with far more control options, which I don't need. All I need is for it to give me 3 ph 240V at 50Hz. End of! It seems fine, giving the option again of a 2 wire logic input across which I have the same switch as before.
 
The 28 has 50Hz and 2 wire control as factory default settings, and I have set it to 'auto-reset' (I think!) after a stop.
 
But it won't go. It only goes to a 'ready' state but will not power up to 50Hz.
 
Can anyone help in pointing me in the right direction here? There seems masses for configuration options which I surely don't need, but there must be one somewhere which I do need. Help!
 
Chris
LADmachining17/05/2011 14:31:37
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126 forum posts
11 photos
Inverters (especially modern ones) should have their outputs connected directly to the motor with no switchgear in-between.
 
I expect that you are getting no output because the inverter is detecting the open circuit on its outputs due to the switches being open.
 
Direction and speed control should all be controlled via the logic and analogue inputs to the inverter.
 

Edited By LADmachining on 17/05/2011 14:32:46

Steve Garnett17/05/2011 21:03:43
837 forum posts
27 photos
There are several points to make about this:
 
Firstly, since this is an electronic device, and the old one had been working, presumably fine, why did it choose now to stop? Electronic devices of this type don't tend to stop working unless there's a good reason, so this may be more important than you might think.
 
Secondly, the chances of the old controlling system working directly with a new inverter, even from the same manufacturer, are not good. Chances are that the wiring will have to be modified to take account of the differences.
 
Thirdly, I'm a little concerned about the high/low speed switching arrangements. Is this a dual-winding motor? If it is, I have to say that they can be a complete nightmare when it comes to inverters. I'm aware of one installation where to get this to work at all without blowing up triacs on switching, zero-speed sensing and some extra logic had to be employed. The back emf generated in the winding not being used (especially when switching from high to low speed) can produce enough oomph to destroy even massively oversized and over-rated triacs.
 
I had a quick look at the manual for the new inverter, and it looks as though it follows a fairly typical layout, so the chances are that if it won't start at all, you need first to be looking at the basic run diagram and where the links are. Then you need to look at the settings. And LADmachining is quite correct - just make sure initially that you have one winding (if there are two) connected permanently to the inverter output, or nothing will happen.
 
So initially, can you confirm exactly what sort of motor this is that you are using?
confused.eng17/05/2011 21:25:58
19 forum posts
2 photos
Any chance of posting a drawings of the electrical wiring.
Modern inverters usually have lots of options and some of the newer ones have an Emergency Stop feature built in that must be wired/configured correctly.
 
Not played with Altivar for quite a while, some drives have config macros that allow the basic settings to be configured relatively easily. Usually things like voltage, current, power factor, rated speed, etc.
 
Big question is, why did the old unit go bang?
Inverters are one of those items that you must read the manual, not just the 4 page flyer usually labelled 'not quite' Getting Started. Altivar's use to come with a CD that has additional manuals on them, unless Group Schneider have decided to reduce costs further. The manuals can be downloaded from the Group Schneider website but can take a bit of finding.
 
 
Steve Garnett17/05/2011 21:52:03
837 forum posts
27 photos
You can download the Altivar 28 manual very easily from here. Yes, this is the 88 page version.
ChrisH18/05/2011 16:43:09
1023 forum posts
30 photos
Hello, and thanks to all that have responded.
 
I have now managed to get this going, after obtaining some advice from Direct Industrial who also do reconditioned inverters at a good price and with a 'comprehensive 12 months warranty'. Needless to say, I have no other attachment to this company other than the advice they gave me!
 
Anyway, firstly, I had to reset the low speed setting on the inverter to 50Hz from the factory default of 0Hz - I in my naivety had assumed that because the machine had been set to being a 50Hz machine then that would be that. Then I found that it still would not start up if either of the 2 switches between it and the motor were in the 'off' position. Instead it would sense an 'open phase fault' situation on the motor and stop. However, this protection is offered with the option to be switched off in the programming if precisely this condition (of a switch between inverter and motor) exists, so, once that option had been taken it worked!
 
For those who inquired about the motor, the lathe is a German Weiler 280 from the mid-60's, with a two speed reversing motor fitted as standard. There are 2 sets of windings; the low-off-high speed switch switches between these two windings. It has run in the past OK as said before; it was designed to do this!  I think in this instance when the inverter went phut I had an earth fault which caused the damage; in fact, I am certain I had because I subsequently found one found. All wiring has been now been throughly checked through again and is fine (he says with quite some hope!!) so hopefully that will be that. The lathe is a good one but has obviously had some use over the years; there is some wear in the bed but it is not so bad as to warrant a regrind. You just have to take account of it, but I have not had a problem so far with it. It has a range of speeds in high and low mode via a set of stepless adjustable pulley wheels and a 2 belt drive between motor and headstock, powered cross feed and longitudinal feed and screwcutting feed, and gear wheels to cut just about all metric and imperial threads and interestingly, for a German machine, has the cross feed and top slide graduations marked in 'thous'.
 
Chris

Edited By ChrisH on 18/05/2011 16:44:41

Steve Garnett18/05/2011 17:47:33
837 forum posts
27 photos
Posted by ChrisH on 18/05/2011 16:43:09:
For those who inquired about the motor, the lathe is a German Weiler 280 from the mid-60's, with a two speed reversing motor fitted as standard. There are 2 sets of windings; the low-off-high speed switch switches between these two windings. It has run in the past OK as said before; it was designed to do this! I think in this instance when the inverter went phut I had an earth fault which caused the damage; in fact, I am certain I had because I subsequently found one found. All wiring has been now been throughly checked through again and is fine (he says with quite some hope!!) so hopefully that will be that.
 
Hmm... those switching 3-phase motors are designed to be switched when running from a hefty great 3-phase supply from a transformer, not from an inverter!
 
I think that once I'd found even a single earth fault, I'd be inclined to rewire everything from scratch. Mainly because when it comes to things like this, hope is the last thing you should be relying on, quite frankly. And out of interest, where was the fault?

Edited By Steve Garnett on 18/05/2011 17:49:04

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