yet another motor question
- Thread starter andy
- Start date
Sponsored Links
This can be done with (DC) Direct current injection on the motor windings,
Which will act as a braking effect on the motor,
The level of DC injection depends on the size of motor (Kw) and the amount of decceleration,
But you could also use a "Soft Stop"
Which will act as a braking effect on the motor,
The level of DC injection depends on the size of motor (Kw) and the amount of decceleration,
But you could also use a "Soft Stop"
B
Big_Spark
Andrew, the only realistic way to safely slow a 3 phase motor is with an inverter, these alter the frequency of the supply thus effecting the rotational speed of the rotor.
All other options are pie in the sky and likely to end in tears with expernsive consequencies.
All other options are pie in the sky and likely to end in tears with expernsive consequencies.
Good to see you FWL.
Being the motor expert you are, how would a motor stand if you 'reversed' a star-delta starter? IE, running in delta config, and then switch to star?? Would this slow it, or wreck it
Being the motor expert you are, how would a motor stand if you 'reversed' a star-delta starter? IE, running in delta config, and then switch to star?? Would this slow it, or wreck it
Sponsored Links
B
Big_Spark
Andrew, a basic description of soft stop is a freqency change to slow the motor from full speed to full stop in a controlled manner. This system is often used in process control environments, but there are many applications. The point is that you still need to have an inverter for this system to work effectively, so you might as well install one for standard speed control. The system is also called "Dynamic Braking"
For inverters try this link.
http://www.cse-distributors.co.uk/abbdrives/index.htm
For inverters try this link.
http://www.cse-distributors.co.uk/abbdrives/index.htm
Andrew -
An invertor can be used to change the motor speed, but it is totally OTT if all you want is a soft stop. Kavozzy has suggested the correct way to do it, which is much cheaper than an invertor. Here's a link to look at:
http://www.engineeringtalk.com/news/abc/abc105.html
An invertor can be used to change the motor speed, but it is totally OTT if all you want is a soft stop. Kavozzy has suggested the correct way to do it, which is much cheaper than an invertor. Here's a link to look at:
http://www.engineeringtalk.com/news/abc/abc105.html
B
Big_Spark
Stoday, good link, never came across this system before, but then I have not delat with this type of machinery, however, without knowing the type of use this motor Andrew needs information, this system may not be what he is after
If he wants a "soft braking" system to operate at all times, then an inverter, whilst expensive, is the only way to achieve this, further as his original quation regarded the speed reduction of the motor, the installation of an inverter will achieve both his aims with one piece of kit, thus reducing capiatol outlay of multiple equipment and installation costs, plus the ongoing servicing and maintenance costs associated with two seperate bits of kit.
If he wants a "soft braking" system to operate at all times, then an inverter, whilst expensive, is the only way to achieve this, further as his original quation regarded the speed reduction of the motor, the installation of an inverter will achieve both his aims with one piece of kit, thus reducing capiatol outlay of multiple equipment and installation costs, plus the ongoing servicing and maintenance costs associated with two seperate bits of kit.
Does the braking system above utilise feedback?As the motor is on load as it slows and having no idea what the effect of this load is on the motor at different speeds, it may pay to go down the road of invertor as suggested by FWL as a suitable one will utilise the dynamic braking system as described before, this is the most safe and smooth way to slow the motor up as it continuosly monitors speed in conjunction with braking as the term dynamic suggests.
this is of course if the driven load needs this level of sophistication, what's the application?
this is of course if the driven load needs this level of sophistication, what's the application?
I remember we had them fitted to all our woodworking machines and it does stop the motor dead straight away. The one we has (might be out of date now) was a like telescopic car aerial acting as a switch hanging down from above and pull it down to what height you want it.
FWL This is just for you
DC injection and soft starts are another method,
Just because you have never heard of it does not mean it does not exist,
Looks like 2.5mm2 cpc in 6mm2 T&E cable is more commonly used than a 4mm2 cpc
I have got a BS88 service fuse in my home, And have seen them many times in other domestic and commercial premises,
Looks like you don't get out of your little corner of the world that much
But in other parts of the country we have wonderful things like
BS88 fuses in domestic and commercial premises ,
2.5mm2 cpc in our 6mm2 T&E cable,
DC injection and soft starts for our motors,
These might be pie in the sky to you but they do exist in this country
So don't knock what other qualified and experienced sparks are saying just because you have not heard of these things,
You just make us all (including yourself) look like fools,
FWL_Engineer said:
DC injection and soft starts are another method,
FWL_Engineer said:
Just because you have never heard of it does not mean it does not exist,
FWL_Engineer said:
Looks like 2.5mm2 cpc in 6mm2 T&E cable is more commonly used than a 4mm2 cpc
FWL_Engineer said:
I have got a BS88 service fuse in my home, And have seen them many times in other domestic and commercial premises,
Looks like you don't get out of your little corner of the world that much
But in other parts of the country we have wonderful things like
BS88 fuses in domestic and commercial premises ,
2.5mm2 cpc in our 6mm2 T&E cable,
DC injection and soft starts for our motors,
These might be pie in the sky to you but they do exist in this country
So don't knock what other qualified and experienced sparks are saying just because you have not heard of these things,
You just make us all (including yourself) look like fools,
B
Big_Spark
Paul, please read the ENTIRE thread before posting.
I have stated much of what you have said, as you have so eloquently posted. I have not come across the DC injection system as a brake before, I did not say it did not exist, and made no comment on it UNITIL AFTER I had read Stoday's link which I then simply said that this may not be what Andrew is looking for. At no point did I slag off the system, my original post and that mentioning the system crossed so to speak and there was no implication intended. By Pie in the sky I meant other mechanical systems some companies peddle that do often end in tears.
Regarding the BS88 Paul, BS88's are used in Commercial and Industrial premises, but in modern cut-outs that have been installed in the last 35 years, in domestics they are BS1362 fuses, the same as you have in a plug..Only a darn sight bigger!! I know that many people think the Cut-out fuses are BS88's, due to similarity to some BS88 patterns, but they are in fact BS1361's. This is not to say one cannot find it's way into a cut-out, but it is not standard Install.
Regarding the T&E, we cleared that up in a wholly different thread so please don't bring it up in this one which has no bearing on this discussion, you simply confuse the issue and make yourself look pedantic which I know from past experience you are usually not.
Regarding looking like fools, your post comes across as making you sound a fool as you have not bothered to read all the threads you quote from properly and even this one you have failed to read the entire thread. Further you are introducing comments to this thread which have no bearing on it. Paul, I know you know what your talking about, I know you are not a fool, so please try not to post like one.
Edit
Changed the Fuse BS number from 1361 to the correct 1362 as I mistyped and didn't notice. Thanks to Stoday for the heads up.
I have stated much of what you have said, as you have so eloquently posted. I have not come across the DC injection system as a brake before, I did not say it did not exist, and made no comment on it UNITIL AFTER I had read Stoday's link which I then simply said that this may not be what Andrew is looking for. At no point did I slag off the system, my original post and that mentioning the system crossed so to speak and there was no implication intended. By Pie in the sky I meant other mechanical systems some companies peddle that do often end in tears.
Regarding the BS88 Paul, BS88's are used in Commercial and Industrial premises, but in modern cut-outs that have been installed in the last 35 years, in domestics they are BS1362 fuses, the same as you have in a plug..Only a darn sight bigger!! I know that many people think the Cut-out fuses are BS88's, due to similarity to some BS88 patterns, but they are in fact BS1361's. This is not to say one cannot find it's way into a cut-out, but it is not standard Install.
Regarding the T&E, we cleared that up in a wholly different thread so please don't bring it up in this one which has no bearing on this discussion, you simply confuse the issue and make yourself look pedantic which I know from past experience you are usually not.
Regarding looking like fools, your post comes across as making you sound a fool as you have not bothered to read all the threads you quote from properly and even this one you have failed to read the entire thread. Further you are introducing comments to this thread which have no bearing on it. Paul, I know you know what your talking about, I know you are not a fool, so please try not to post like one.
Edit
Changed the Fuse BS number from 1361 to the correct 1362 as I mistyped and didn't notice. Thanks to Stoday for the heads up.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
