CTL MIDI GB 110V minimum outlet current?

[Dainius G]

What is the minimum current/wattage required on the tool plug to autostart the dust extractor?
Thanks. ;]

 

[Holmz]

1/2 of SFA... Just a transformer will start it.
Bring in a phone charger and see if that starts it... I bet it does.

 

[Dainius G]

Well I have a mitresaw with a custom built in led blade light which is powered by a phone charger.
The led is driven with 100mA @ ~3.0V so = 0.3W. And that is not enough to kick in the extractor. So the question still stands of how much current draw does the plug need to start up the extractor?  [wink]

 

[Holmz]

100v to 3V means that the transformer is ~30:1... so we know the 100mA at 3V was ~3mA a 110v.
I suppose if you were daring and careful you could noodle it out with some resisters.
V=IR so I = V/R
110v /10kOhms produces 10mA
5k-ohms is 20 mA
2k-ohms is 50 mA

Easier/safer would be a small night light pugged in say a 10W (100mA) or 3W (30mA)

Ideally they would have that in a specification.

 

[Bohdan]

A transformer without a load on it is in itself a reactive load. This means that while it is not drawing any power (watts) it is still drawing a significant current. This current is nearly 90 degrees out of phase with the voltage so there is little or no power being consumed.

Another way of putting it is to say that the power factor is close to zero. However if the CT's sensing circuitry is designed to trigger on current flow, rather than power consumed, it would see the unloaded transformer as a significant load and run the extractor.

This situation gets worse the larger the rating of the transformer so it may be possible to find a transformer that is small enough not to trigger the CT but it would not supply enough power to run the tool.

 

[Dainius G]

Ok I`ve just tried connecting one and then two(in parallel) 220V 50W spotlight bulbs, they light up dimly but they do not trigger the autostart.
Could it be that the circuit is specifically designed for inductive and not resistive loads? [huh]

 

[Bohdan]

Try a 110v bulb. That should draw sufficient current.

 

[Holmz]

On a 230v unit...

An iron works activates the vacuum.
The transformer on but not supplying power also activates the vacuum.

And a 20w globe does not activate the vacuum.

I could dig out the variac and amp meter...

 

[Bohdan]

On a 230v unit...

[member=40772]Holmz[/member]

The tread topic is "CTL MIDI GB 110V minimum outlet current?"

 

[Holmz]

I know [member=36526]Bohdan[/member] , but there are also people using these in 230v countries.
I suspect that the same circuit is used, and it begs the question of whether it is like an RCD/GFI where it latched instead of interrupts.

The transformer even with no load may have the return current enough out of phase that it sets up an imbalanced magnetic field.
A resistive load would have a net-zero magnetic field.

Maybe it is done with only one magnetic field and strength is used?

I dunno...

 

[Rick Christopherson]

A transformer without a load on it is in itself a reactive load. This means that while it is not drawing any power (watts) it is still drawing a significant current. This current is nearly 90 degrees out of phase with the voltage so there is little or no power being consumed.

Another way of putting it is to say that the power factor is close to zero. However if the CT's sensing circuitry is designed to trigger on current flow, rather than power consumed, it would see the unloaded transformer as a significant load and run the extractor.

This situation gets worse the larger the rating of the transformer so it may be possible to find a transformer that is small enough not to trigger the CT but it would not supply enough power to run the tool.

No, that is not how a transformer works. Whatever is happening on the output side of a transformer appears on the input side, and that includes an open circuit. Virtually no current will flow in a transformer with no load connected.

Of all the inventions man has created, the simple transformer is the closest to perfect. The real life transformer behaves very close to the mathematics of an ideal transformer. When people say their transformers draw significant current when not in use, it's probably because they aren't transformers at all, but electronic power converters. If you have a true transformer, it would not trigger a CT vac.

 

[Bohdan]

No, that is not how a transformer works. Whatever is happening on the output side of a transformer appears on the input side, and that includes an open circuit. Virtually no current will flow in a transformer with no load connected.

Of all the inventions man has created, the simple transformer is the closest to perfect. The real life transformer behaves very close to the mathematics of an ideal transformer. When people say their transformers draw significant current when not in use, it's probably because they aren't transformers at all, but electronic power converters. If you have a true transformer, it would not trigger a CT vac.

If that is true then why do all of the users in Britain that plug a transformer into their CT find it running with no tool connected.

 

[Rick Christopherson]

No, that is not how a transformer works. Whatever is happening on the output side of a transformer appears on the input side, and that includes an open circuit. Virtually no current will flow in a transformer with no load connected.

Of all the inventions man has created, the simple transformer is the closest to perfect. The real life transformer behaves very close to the mathematics of an ideal transformer. When people say their transformers draw significant current when not in use, it's probably because they aren't transformers at all, but electronic power converters. If you have a true transformer, it would not trigger a CT vac.

If that is true then why do all of the users in Britain that plug a transformer into their CT find it running with no tool connected.

Because what they are calling a transformer is most likely an electronic power supply.

 

[Holmz]

No, that is not how a transformer works. Whatever is happening on the output side of a transformer appears on the input side, and that includes an open circuit. Virtually no current will flow in a transformer with no load connected.

Of all the inventions man has created, the simple transformer is the closest to perfect. The real life transformer behaves very close to the mathematics of an ideal transformer. When people say their transformers draw significant current when not in use, it's probably because they aren't transformers at all, but electronic power converters. If you have a true transformer, it would not trigger a CT vac.

If that is true then why do all of the users in Britain that plug a transformer into their CT find it running with no tool connected.

Because what they are calling a transformer is most likely an electronic power supply.

I can pull my transformer apart... It must be 25-30 years only and feels like massive iron core is in it.
There is a breaker and a small lamp that lights the switch.
I am assuming it is an old-school proper transformer, and not a switching power supply.

It alights the CT-26 every time... maybe I should get the Amp meter out?

 

[Bohdan]

It alights the CT-26 every time... maybe I should get the Amp meter out?

Good idea. Some actual measurements might shed some real light on the subject.

 

[Dainius G]

Ok, so 60W 110V bulb does not start the CT, 500W 110V halogen does. So that narrows it down to 60W-500W load requirement. This probably means that the load can be reisistive and since the least power drawing festool power tool (designed to work with CT) seems to be the Eccentric sander ETS 125 that rates @ 200W narrows it to 60W to 200W.
I guess I should have explained why am I asking about this, well while the autostart function is a nice feature, I find it inefficient for my purposes. I lay wooden floors for a living, when working my CT is connected to my mitresaw to chop the boards and then finishing trim. I work fast and I find more so then not my CT only spools up when I`m already halfway through my material(=a lot of dust). So I want to add a sensor/dummyload to my mitresaw to kick in the CT few moments early as I approach the machine, perhaps even add a few button controlled pre-set modes. I know that one day these features will be incorporated in most festool machines as the IOT progresses but for now I`d be happy with getting this Idea working  [smile]
BTW my 3.3kVA 240V to 110V transformer starts (atleast what my multimeter clamp can read)(NO LOAD) with more than 15Amps and then quickly settles to about 1.3-1.4 amps which means its ~ 310-325 Watts is more than enough to start the CT.

 

[Holmz]

Ok, so 60W 110V bulb does not start the CT, 500W 110V halogen does. So that narrows it down to 60W-500W load requirement. This probably means that the load can be reisistive and since the least power drawing festool power tool (designed to work with CT) seems to be the Eccentric sander ETS 125 that rates @ 200W narrows it to 60W to 200W.
I guess I should have explained why am I asking about this, well while the autostart function is a nice feature, I find it inefficient for my purposes. I lay wooden floors for a living, when working my CT is connected to my mitresaw to chop the boards and then finishing trim. I work fast and I find more so then not my CT only spools up when I`m already halfway through my material(=a lot of dust). So I want to add a sensor/dummyload to my mitresaw to kick in the CT few moments early as I approach the machine, perhaps even add a few button controlled pre-set modes. I know that one day these features will be incorporated in most festool machines as the IOT progresses but for now I`d be happy with getting this Idea working  [smile]
BTW my 3.3kVA 240V to 110V transformer starts (atleast what my multimeter clamp can read)(NO LOAD) with more than 15Amps and then quickly settles to about 1.3-1.4 amps which means its ~ 310-325 Watts is more than enough to start the CT.

The Starmix run for ~10 seconds after the saw is off... But that will not help spool up.

If you are working that fast then leave the thing on manual-on.
Or maybe you halgogen light at the saw and turn it on when you want to run the saw.

 

[Bohdan]

[member=60310]Dainius G[/member] The CTs have a remote switch activation mode. It is one of the optional extras that can be fitted to the extra outlet hole in the front panel. It is a connector module #496143 that is designed to switch the CT on when using the boom arm but you may find that a expensive option.