Lynx SM 16 wiring anomoly - help

Got a Lynx SM 16 controlling a servo spindle drive, it has a contactor between the main power supply (240v) and the lynx. However the contactor seems to be wired so the live is going to the Neutral on the Lynx. I am a little worried as i do not want to apply power and blow it up. See picture:
(PS: the contactor was pre-wired - I didn't do it)

Pic below has contactor info inlaid
Attachment 28854

Please advise

thanks

While it's not technically correct it won't do any damage because it's AC. However, for the 1 min, it takes to swap it over then I would do so just to save any confusion.

Quote:

---

Originally Posted by JAZZCNC

While it's not technically correct it won't do any damage because it's AC. However, for the 1 min, it takes to swap it over then I would do so just to save any confusion.

---

Thank you - I don't suppose you know anything about contactors do you?

This one looks wired as if it is an AC coil (the 240v neutral loops back into the coil). Any idea what sort of ampage the coil will use on these? I have looked all over tinterweb and can find zero info.

I was wanting to put a 1 amp fuse on it.

thanks again

Quote:

---

Originally Posted by Nemo1966

Thank you - I don't suppose you know anything about contactors do you?

This one looks wired as if it is an AC coil (the 240v neutral loops back into the coil). Any idea what sort of ampage the coil will use on these? I have looked all over tinterweb and can find zero info.

I was wanting to put a 1 amp fuse on it.

thanks again

---

Typically on an AC contactor of this size, you'll have a Pickup rating of around 70Va with a Holding Va of about 8-10. So on 230vac, you are looking in the 0.4a range at worst on start-up and far less when holding so your well in at 1A.

Quote:

---

Originally Posted by JAZZCNC

Typically on an AC contactor of this size, you'll have a Pickup rating of around 70Va with a Holding Va of about 8-10. So on 230vac, you are looking in the 0.4a range at worst on start-up and far less when holding so your well in at 1A.

---

Absolute gent - thank you very much

Quote:

---

Originally Posted by JAZZCNC

Typically on an AC contactor of this size, you'll have a Pickup rating of around 70Va with a Holding Va of about 8-10. So on 230vac, you are looking in the 0.4a range at worst on start-up and far less when holding so your well in at 1A.

---

One last thing, if I may. The manual seems to be a bit ambiguous with regards to the 0 - 10v speed controller input.
Attachment 28857

"Set speed Term 3: Potentiometer minimum or 0 to +10V, impedence 100K ohm filtered"

So, Potentiomemrer or 0 - 10v, yep all good... impedence 100K filtered???

The diagram shows:
Attachment 28858

The reason I ask is that only 2 wires were connected originally (to 2 and 3). I'm guessing a 0 - 10v.

I do not quite understand this sign in the picture:
Attachment 28859


I am connecting to an MB3 breakout board with a 0 - 10v, page 20 on the link below for details
http://www.cncroom.com/downloads/MB3...al%20E13R1.pdf


Any help gratefully recieved

I would guess that 100K impedance means that internally the input has the equivalent of a 100K resistor (impedance is AC resistance, so not quite the same as DC resistance). This is to limit current when the potentiometer is at the 10v end.


My further guess is that the input has an internal filter.

Please somebody inform me if I am way off beam!

Rob.

Quote:

---

Originally Posted by cropwell

I would guess that 100K impedance means that internally the input has the equivalent of a 100K resistor (impedance is AC resistance, so not quite the same as DC resistance). This is to limit current when the potentiometer is at the 10v end.


My further guess is that the input has an internal filter.

Please somebody inform me if I am way off beam!

Rob.

---

Mmmmm now I assumed the 0 - 10v input was DC :culpability:

Quote:

---

Originally Posted by Nemo1966

Mmmmm now I assumed the 0 - 10v input was DC :culpability:

---

It is. but they quoted an impedance which is generally used for AC signal inputs. 100K impedance means that the current from the pot wiper is very low.

Quote:

---

Originally Posted by cropwell

It is. but they quoted an impedance which is generally used for AC signal inputs. 100K impedance means that the current from the pot wiper is very low.

---

OK - (probably got this wrong) are you saying the input impedence is basically circuit to restrict the ampage coming in???? and are you saying this circuit is already built in?

It seems so. If the input were the full 10v, it would give a current dependant on the output capability of the 10v source. The input terminal has to have some protection against too much current. It is also filtered to get rid of any induced voltage spikes to give a more stable control of the speed.

Quote:

---

Originally Posted by cropwell

It seems so. If the input were the full 10v, it would give a current dependant on the output capability of the 10v source. The input terminal has to have some protection against too much current. It is also filtered to get rid of any induced voltage spikes to give a more stable control of the speed.

---

You see that's where it is confusing... looking at the diagram
Attachment 28860

The circuits (to me) at the bottom reopresent the circuit a user has to add. This is because the switch from 5 - 7 is not on/in the board, the user adds that.

Does that make sense?

I'm in agreement with Cropwell's interpretation. There's any engineering "wet thumb" rule that you design the input impedance at least 10 times the source impedance in order to not substantially influence the input. So, 10k input pot, 100k input impedance - rule is met. (ignoring balanced input design etc).

Don't get hung up on impedance over resistance.

And Nemo - Because I'm in a good mood I'm going to agree with you too - at least re. the circuit outside of the box being that that the user has to add.

Quote:

---

Originally Posted by Doddy

I'm in agreement with Cropwell's interpretation. There's any engineering "wet thumb" rule that you design the input impedance at least 10 times the source impedance in order to not substantially influence the input. So, 10k input pot, 100k input impedance - rule is met. (ignoring balanced input design etc).

---

I'm still lost... "Set speed Term 3: Potentiometer minimum or 0 to +10V, impedence 100K ohm filtered"


Do I need the 10k pot if using 0 - 10v from a spible card?

It's written to confuse. My interpretation that I'm very comfortable with:


"Potentiometer 10k minimum" : There are other on-board controls to set the minimum speed and I guess they don't want to influence that circuitry by the installer using a silly-small potentiometer. I would expect the on-board pot to be a lowish value to provide an offset above zero when placed in series with the speed control pot. If the speed control pot was too small then the on-board pot would become more dominant as part of the potential divider, and the effective speed control would be limited to a higher minimum speed. Or, potentially disk damaging the on-board control. However, this is belts-and-braces stuff.



"Impedance 100k ohm filtered" - as Cropwell said - it characterised the input equivalent circuit, more or less. Nothing to do with the external control.



"0 to +10V" - as an alternative to using the recommended minimum 10k potentiometer, you are able to drive a speed command in the range 0-10V, wrt 0V/pin 4 (note: NOT wrt pin-2 used for the potentiometer).



So, yes, you can drive the input with 0-10V from the spindle card (your words), provided that you can share a common 0V reference from the spindle-card output to the 0V on this SM 16 / pin 4.

Quote:

---

Originally Posted by Doddy

It's written to confuse. My interpretation that I'm very comfortable with:


"Potentiometer 10k minimum" : There are other on-board controls to set the minimum speed and I guess they don't want to influence that circuitry by the installer using a silly-small potentiometer. I would expect the on-board pot to be a lowish value to provide an offset above zero when placed in series with the speed control pot. If the speed control pot was too small then the on-board pot would become more dominant as part of the potential divider, and the effective speed control would be limited to a higher minimum speed. Or, potentially disk damaging the on-board control. However, this is belts-and-braces stuff.



"Impedance 100k ohm filtered" - as Cropwell said - it characterised the input equivalent circuit, more or less. Nothing to do with the external control.

"0 to +10V" - as an alternative to using the recommended minimum 10k potentiometer, you are able to drive a speed command in the range 0-10V, wrt 0V/pin 4 (note: NOT wrt pin-2 used for the potentiometer).

So, yes, you can drive the input with 0-10V from the spindle card (your words), provided that you can share a common 0V reference from the spindle-card output to the 0V on this SM 16 / pin 4.

---

Firstly - thank you for taking time to reply to my mind-numbingly simple posts.

So 0v to pin 4 (what does wrt denote please?). Do I connect +10v to pin 1 or pin 3?

Pic below is MB3 0-10v analogue

Attachment 28864

thanks again

Connect A0 to pin 3, AG to pin 4. Leave pin unconnected.

Wrt = with respect to. A voltage is the potential difference between two points, not necessarily always to ground or 0V, you could look at the wiring for the pot and decide to measure the analogue demand between pins 2&3 for example. Pedantic perhaps but I tend to reference where a voltage is measured between, and being lazy I say what point, with respect to another point.

If you have to ask the question, then I’ve failed in providing an answer that isn’t clear.

Quote:

---

Originally Posted by Doddy

Connect A0 to pin 3, AG to pin 4. Leave pin unconnected.

Wrt = with respect to. A voltage is the potential difference between two points, not necessarily always to ground or 0V, you could look at the wiring for the pot and decide to measure the analogue demand between pins 2&3 for example. Pedantic perhaps but I tend to reference where a voltage is measured between, and being lazy I say what point, with respect to another point.

If you have to ask the question, then I’ve failed in providing an answer that isn’t clear.

---

Actually that is what I thought, I was just double checking. I really didn't want to blow it up for the sake of asking again.

News: Tried it - started first time, brilliant.

Thank you - your time and effort is most appreciated.