Outside the box

A client needs to heat a wire to cut some plastic film.

Its resistance is 3.6 Ohm.

We presently use a KBIC-120 (very cheap DC drive card ).

With the external adjustment pot. we can set the color of the heating wire to the disired level. Floating common isolates the circuitry.

We install this on a control panel. To make it work we need to install a 460/120/1500VA close type x-former.

The total cost is 110$ for the drive and $135 for the x-former. (total $235CAN)

When this option is not on his system he only needs a 500VA open x-former IN the panel.

He suggested that we use a step down x-formet and a light dimmer instead... to reduce the cost (darn those mechanical eng.)

We refuse to do it and now he is not a happy camper.

Has anybody got a trick to do this. We need 10DC Amps accross the wire?

This is a shot in the dark. Who knows

This guy is nuts! The engineering alone for alternates is going to be more than $250! Tell him he can pick the components, and sign off in writing that he assumes full responsibility and your costs for troublshooting at $100 per hour. Maybe he will see the light.

Pierre,
Why are you using DC? Most wire cutters just use a step-down transformer - 15 to 24 vac secondary - to heat the wire.Put a SCR voltage control on the primary side, and a good contactor too and the cutting wire in series w/ a slow blow fuse and you should be good to go!!

David

Y'all know I worked ALOT on sealers with hot wires. The systems I worked with had a multi-tap xformer with a large (wattage) selector switch. In my app I stayed with the mulit-tap xformer because it was what we had but there are other ways...I dont think I would use a light dimmer tho.

I needed to pulse the wire so I used a solid state relay to actually pulse the xformer. This allowed me to drive it with an ordinary DC output.

The system I did this on actually went from an avg of 4-6 pieces a minute to the capability of 30 pieces a minute. The system could run at 20 pieces a minute but once this sealer was running correctly, without the wire burning out 3 or 4 times per shift, they found they ran good at 12 pieces per minute. They ran so much better they eliminated a shift from production.

I didnt use DC either except the plc output, the wire was heated with AC direct from the xformer.

Pierre

You can use Solid State Relay with pot so you can change the voltage
on your wire.Its not regular SSR it work like light dimmer but more hevy duty.(If you will like it let me know I will look for the manufacture name).It cost here about $40US.
you can switch transformer with this SSR and limit the output to
50-100% of voltage.So if you need 12-24V on the wire take 120V/24V transformer like in my pic.
I hope I helped in somthing.

I guess he already has solution which WORKS and it is
inexpensive. Problem is customer who has own "solution"
(at least he thinks so).

Transformer idea and control on the primary circuit is very
popular and elegant solution. However most light dimmers are
not good for inductive load such as transformer. Using
controls like for drill gun would be better but who cares.
That is not the topic... Someone is counting pennies!!!

I guess just don't like overly demading types. Usually they
get you in trouble with all demands or "solutions".

For example:
Most of my time is usually spend on finding all noname or
vanila brands of every ittle devices, because customer wants to
"standardize and keep it in stock".

And after you spend all time and later on something does break,
they run like headless chicken because they don't have it
(great standard banghead ).

Some of the specs are HUUUGE (one of the customer has spec that
is over 2600 pages long - over 9mb compressed).

They don't understand what it takes to come up with concept and
then design, find who sells their brands then order parts,
machine, paint, assemble, setup, program, write documentation etc.
and all of that in couple of weeks. Then you get somebody to
show up with his idea... Give me a break...

I agree that using a standard dimmer switch is undesirable, but it is quite common for wire sealers to use dimmers which are specifically designed for transformers such as commonly used in lighting. However, I can't say I've seen one that is up to controlling a 1500VA transformer.
Another popular (and more reliable) method is to use a variac (variable transformer) for the primary input voltage of the main transformer. I also don't see why you need DC, I have never seen that on a hot wire application.

Anthony

I have convinced him that this $100 000 machine does not deserves the cheap stuff.

But am still curious about ArikBY's SSR. So if you can post the brand I will perhaps get me one to play with.

The use of this DC drive serves also for safety.

Tanck all for the inputs.

panic mode wrote:
They don't understand what it takes to come up with concept and
then design, find who sells their brands then order parts,
machine, paint, assemble, setup, program, write documentation etc.
and all of that in couple of weeks. Then you get somebody to
show up with his idea... Give me a break...

Click to expand...

The argument was over in 10 seconds but I still had to listen

David_Emmerich wrote:
Why are you using DC? Most wire cutters just use a step-down transformer - 15 to 24 vac secondary - to heat the wire...

Click to expand...

The wire is 6 feet long and will need about 40 volts with 10Amps. With this KBIC we can limit the current output...

Tom Jenkins wrote:
This guy is nuts! ...

Click to expand...

Pierre

You can get it here:

http://62.110.11.151/pdf/UK/RE-E.pdf

I am Glad the problem finished in good way.

Thats similar to the one I used, I didnt worry about limiting because the xformer was multi-tapped...ie it used a 6 position selector switch that ended up always at position 1 which would probably have been around 24vac. I also had to use DC in the system, the plc had 24vdc I/O, the motors used clutches that were 90vdc. The clutches I cheated on and just used a bridge rectifier to convert to DC. I had a 5amp 24v Sola DC power supply for the plc and I/O.

I failed to mention that it was an L-Sealer which actually had 2 wires and the xformer had dual outputs. The listing on the old prints showed it at 65vac for the long wire and 35vac for the short one...I assumed that was at maximum output.

I didnt have to buy any parts when I did this though, we had changed the pulsing over to the solid state relays prior to my upgrades using a plc. I just ripped out the spaghetti wire and old style power relays and used a plc with octal based relays that I had previously pulled from a machine.

Ron

This SSR save you the need of multi tapped transformer.
It work like light dimmer on the primary of the transformer,and reduce the voltage.You cannot go too low otherwise the transformer wouldnt function.So you need to limit the Pot.
Dc control voltage is not require here.
I think what you mean is SSR who work with pulses from the PLC.
Its better system, but need more component.

Arik