[hutchison]

hello folks, i'm just piecing together a cabinet for an nc spindle control. Since i'm not a professional cabinet builder and there has to be a first right!, i have some things i need to ask ..

I'll be using a 240-110VAC transformer supply at 2Kw for power in.
The drive it will be powering is a dc servo @ 1.6kw for a spindle.

I will also be using a 110AC/5DC tranny @ 4.4A max to run limit switch signals and the various interface cards i need to hook the drive up to a PC, with opto-isolation etc.

firstly the power runs in through a 110 16A plug into the cabinet , then through a 32A 4 pole isolator (its all i had).

i was considering using the following,

20A 2 stage high attenuation emc filter, to filter everything.
16A MCB (type K) for the main drive live.
seperate 1A type K MCB's for the supplies to the interface cards, and perhaps a 4A or 6A mcb for the 5dvc supply.

where is best to place the filter? before the breakers or after? and what about rcd's?




sorry, i just noticed i should have put tiis question in the general electronics section, but am unable to move/delete it..

[Al_The_Man]

If you put a filter on the supply entry into the cabinet, all you will achieve is to keep all the electrical noise in the cabinet, which is not really what you want.
You can put a suitable/larger one, as close as possible to the drive in the AC supply, I would place another lighter version on the 120v supply to the PC if, this what you are using.
If this is a DC SCR controller, you may need the reactor choke style, they come mainly in 3 phase configuration, so you may have to make something up if you go that route, or just use two of the phase inputs.
Al.

[hutchison]

hello al, i will be using an external pc. the card I'm using will be a parrallel interface card with step down resistors & opto-iso on return to pc, it will interface the pwm signal from the software convert it analogue volts and then use that to drive the speed +/- 10v reference input on the servo drive, with tach. If the interface card is opto isolated and the pc an external desktop is it still going to need a smaller filter? perhaps a torroidal between the servo reference input and the parrallel interface card ?

i'll put the 2 stage emc as close to the drive as possible in the ac supply. you say larger.. is 20amps good enough you think? the drive apparently draws max 13.3A on the input side..

[Al_The_Man]

Without knowing exactly what your setup is it is hard to make and informed suggestions.
But I have used ferrite toroids in the past on various points including close to the motor, make sure you twist the motor armature wires tightly together, do not twist the ground with them however.
Al.