Discuss Electro Spinning Electrical setup in the Electrical Forum area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

Hi there,
I need some advise pertaining Electro Spinning electrical setup?
A brief intro on that process, a positive DC high voltage low current of 10Kv or more connect to needle of syringe. The negative connected on spinning collector. When syringe in pump, polymers inside will be attracted to collector, like spiderman spinning web.

The negative are always connected to earth grounding which makes the earth grounding like a return path. Is that the right setup?
Thanking you guys in advance.
 

Lucien Nunes

-
Mentor
Esteemed
Arms
It makes sense for the collector (or its terminal of the supply) to be earthed, to maximise the electric field strength around the spinneret and the path away from it. Very little current would pass through the earth connection, as most of the charge carried by the polymer molecules will be given up to the collector and returned directly to the supply. But if there were no connection at all, minute leakage currents could cause the collector potential to drift away from earth and therefore the spinneret potential could drift towards it. This would weaken the spinning effect because although there would be the same potential from spinneret to collector, the field would be compromised by a competing field from the earthed surroundings that are not as negative.
 
It makes sense for the collector (or its terminal of the supply) to be earthed, to maximise the electric field strength around the spinneret and the path away from it. Very little current would pass through the earth connection, as most of the charge carried by the polymer molecules will be given up to the collector and returned directly to the supply. But if there were no connection at all, minute leakage currents could cause the collector potential to drift away from earth and therefore the spinneret potential could drift towards it. This would weaken the spinning effect because although there would be the same potential from spinneret to collector, the field would be compromised by a competing field from the earthed surroundings that are not as negative.

Thank you for your advise. I appreciate it very much.
On my side of the globe, we utilize TN-S earthing system, Earth and Neutral are separated. Earth are solely meant to carry fault current. By connecting the negative spinneret to ground earth, it contravened to the TN-S system. Any advise on that.
 

pc1966

Esteemed
Arms
Supporter
On my side of the globe, we utilize TN-S earthing system, Earth and Neutral are separated. Earth are solely meant to carry fault current. By connecting the negative spinneret to ground earth, it contravened to the TN-S system. Any advise on that.
It is the same basic rule here - you are not permitted to common E & N. Only the supply companies are permitted to do that for TN-C-S systems (and they separate N & E prior to your installation).

However, in the case of a HV DC supply like this it would normally be isolated from the supply L & N via a transformer, so connecting the DC -ve line to earth is not using the supply earth for a normal current, it is simply keeping the isolated DC supply reference to the Earth.

The flow of conventional current on the DC side is from the DC +ve vis the spinner probe and ultimately to the earthed enclosure and back via the DC -ve terminal, it is not circulating back via the TN-S earth.

However, if you had a HV supply directly from the L & N via something like a Cockcroft–Walton multiplier than you have a whole lot of extra problems! That would be a very bad idea and would contravene safe use of the TN-S earth.
 

Lucien Nunes

-
Mentor
Esteemed
Arms
As PC1966 says, on a TN-S system there is no prohibition on using the grounded earth as a reference for other power supplies. AC line current must not be allowed to pass through the earth connection as that would flow all the way back to the supply transformer, but leakage current from the HV power supply will return to the HV power supply and will circulate only within the electrospinning machine and its immediate environment. The connection establishes an equipotential, which is one of the intended functions of grounding.
 
It is the same basic rule here - you are not permitted to common E & N. Only the supply companies are permitted to do that for TN-C-S systems (and they separate N & E prior to your installation).

However, in the case of a HV DC supply like this it would normally be isolated from the supply L & N via a transformer, so connecting the DC -ve line to earth is not using the supply earth for a normal current, it is simply keeping the isolated DC supply reference to the Earth.

The flow of conventional current on the DC side is from the DC +ve vis the spinner probe and ultimately to the earthed enclosure and back via the DC -ve terminal, it is not circulating back via the TN-S earth.

However, if you had a HV supply directly from the L & N via something like a Cockcroft–Walton multiplier than you have a whole lot of extra problems! That would be a very bad idea and would contravene safe use of the TN-S earth.

Hi there,
Thank you again. I do take some time to digest those. Also good to know Cockcroft–Walton multiplier. I've lost that a long time ago till you mention it.

Back to the High Voltage DC power supply, on the input side which is 230Vac, I will have my Earth ground connected to metal chassis of the power supply enclosure.
On the output side, the +ve to the syringe needle and -ve to the spinneret or collector.

My doubt is, should the -ve also be connected parallel to chassis which is also earth ground. There are cases where installer to these equipment request a dedicated earth ground, which means not from equipment chassis but a direct earth ground from distribution board.
[automerge]1600612896[/automerge]
As PC1966 says, on a TN-S system there is no prohibition on using the grounded earth as a reference for other power supplies. AC line current must not be allowed to pass through the earth connection as that would flow all the way back to the supply transformer, but leakage current from the HV power supply will return to the HV power supply and will circulate only within the electrospinning machine and its immediate environment. The connection establishes an equipotential, which is one of the intended functions of grounding.

Hi there,
Thank you for that, "on a TN-S system there is no prohibition on using the grounded earth as a reference for other power supplies". I didn't really thought of that except for equipotential bonding.

Can I say, "leakage current from the HV power supply will return to the HV power supply and will circulate only within the electrospinning machine and its immediate environment" same as in Chassis Grounding like in a vehicle electrical system?
 
Last edited:

Lucien Nunes

-
Mentor
Esteemed
Arms
Sort of. You could connect the car chassis to an earth rod to ensure it was at the same potential as the ground (e.g. to prevent static shocks) but none of the car's DC load current would pass through that connection as its destination is the battery or alternator, not true earth.
 

pc1966

Esteemed
Arms
Supporter
There are cases where installer to these equipment request a dedicated earth ground, which means not from equipment chassis but a direct earth ground from distribution board.
For some instruments that is about reducing noise, but for a HV setup it would not be that.

In some other cases it is about a safe, reliable earth, as some countries do not uniformly apply a type of socket that has a earth pin.

Your info says Singapore, which I guess has the UK style of fused 13A socket? That should be reliable, more so with the "ring final circuit" style of wiring where there are essentially two parallel paths for the CPC back to the board.

But as with all things where an unusually high voltage is involved you really ought to be sure of the supply continuity earth anyway! Also your info says practising electrician, so I have no doubt you have the knowledge and equipment to check that.
 
Sort of. You could connect the car chassis to an earth rod to ensure it was at the same potential as the ground (e.g. to prevent static shocks) but none of the car's DC load current would pass through that connection as its destination is the battery or alternator, not true earth.

Thank you sir, that made me smile, connecting car chassis to earth rod. Nevertheless, I get the picture of static electricity and equipotential bonding and why some cars do have some hanging metallic chain on the bumper.
[automerge]1600626471[/automerge]
For some instruments that is about reducing noise, but for a HV setup it would not be that.

In some other cases it is about a safe, reliable earth, as some countries do not uniformly apply a type of socket that has a earth pin.

Your info says Singapore, which I guess has the UK style of fused 13A socket? That should be reliable, more so with the "ring final circuit" style of wiring where there are essentially two parallel paths for the CPC back to the board.

But as with all things where an unusually high voltage is involved you really ought to be sure of the supply continuity earth anyway! Also your info says practising electrician, so I have no doubt you have the knowledge and equipment to check that.

Thank you sir. That clear most of my doubts. Yes, we're using the 13A socket. Singapore adopt UK electrical code. There are some revision however to adapt to local condition.
 
Last edited:

marconi

-
Mentor
Esteemed
Arms
bigstrong: Generating high voltage electricity using the mains supply is fraught with safety issues. I thought about this and have a suggestion for you. Instead of a high voltage power supply why not integrate into the spinning machine a Wimshurst static electricity generator - see attached image for the basic construction of one. The spinning machine would then generate high voltage only when it was turning. Some arrangement - leakage resistors or shorting to earth (centrifugal switch?) would dissipate any electrostatic electricity when the spinner stopped and/or the access was opened. A Wimshurst machine can generate voltages in the kV range.
 

Attachments

  • wimshurst.png
    wimshurst.png
    517.1 KB · Views: 3
bigstrong: Generating high voltage electricity using the mains supply is fraught with safety issues. I thought about this and have a suggestion for you. Instead of a high voltage power supply why not integrate into the spinning machine a Wimshurst static electricity generator - see attached image for the basic construction of one. The spinning machine would then generate high voltage only when it was turning. Some arrangement - leakage resistors or shorting to earth (centrifugal switch?) would dissipate any electrostatic electricity when the spinner stopped and/or the access was opened. A Wimshurst machine can generate voltages in the kV range.

Hi there Marconi,
Thank you for the suggestion. Wimshurst static electricity generator would be good since its not tapping from the main supply. The issue of pulsating output may not be practical for the electro spinning to work, unless it is smoothen by some capacitor filter. Also, hand cranking the wheel may produce unstable output during the whole spinning process. I'm not sure of that, perhaps I'll DIY one to find out.
 

pc1966

Esteemed
Arms
Supporter
How are you planning on generating the HV supply?

Do you have a specification on:
  • voltage setting range
  • voltage regulation on load
  • current demand
If you are looking at low powers, say of the order of 10W (e.g. 1mA at 10kV) it might be practical to run it from a 12V DC supply and some sort of switching power supply & voltage multiplier as was common for CRT final anode supplies.
[automerge]1600803207[/automerge]
However, if there are trusted commercial suppliers it would be simpler to use that and just check the safety requirements in terms of earthing, RCD protection, cable & connectors used, etc.
 

Reply to Electro Spinning Electrical setup in the Electrical Forum area at ElectriciansForums.net

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
Top