Another pillar drill/VFD question. (Sorry)

[dab4318]

I've recently bought a fobco 7/8 in really good original condition. I already have a little inverter lined up for the job when I finally get it home.

Now my question is can I still use the original switch gear whilst using an inverter? I just want to keep it all original. Its got plenty of speeds so not too worried about the variable frequency.

Thanks for any help in advance.

Dan

 

[Arclikeharrypotter]

You'll be able to keep everything the same, as you'll have 3 phases from the inverter.

 

[brightspark]

You'll be able to keep everything the same, as you'll have 3 phases from the inverter.

that depends if its got a contact starter fitted using a 440v coil and the inverters 240v 3 phase

 

[dab4318]

The motor is dual voltage so I'll need to sort that but that's not a problem. I was just wondering how to wire the inverter up to the drill? Is it just a case of banging the original cable into it? And obviously make sure the links are in the correct terminals on the inverter.

 

[dab4318]

Oh and I'm guessing I might have to change the contactor for a 230v one?

 

[knighty]

post a photo of the back of the switch and someone will be able to tell you

depends if the switch turns it on/off directly, or if the switch works a contactor/relay to turn it on/off :-)


EDIT: post a photo of the motor data plate and take the cover off the motor wiring and post that too :-)

 

[daleyd]

If the contactor is 440 v then it won't work presuming your inverter is a single - 3 phase and your running it off 240v mains - really you shouldn't wire the inverter "through" a contactor anyway, it should be direct out from the inverter to the motor, so in reality you won't need a contactor anyway unless you wanted to wire it "upstream" of the inverter in some way, but you can almost certainly use the switch to start and stop the inverter - you will only be switching low voltage (normally 24 v) generated by the inverter itself which provides a run signal back into the inverter.

Put up a pic of your switch and inverter which will help.

 

[dab4318]

I haven't got the drill home yet but here's a pic of the same drill and the inverter I've got to power it. So am I just better off wiring the motor straight to the inverter? Doing away with the contactor and using the original switch as a signal?

 

[Seadog]

Definitely not.
The inverter won't like a load suddenly being applied to it. You need to have a direct connection to the motor and use the inverter's inputs to control functions. It may work for a while, but I doubt it. Semiconductors don't like sudden surges, they like a steady startup.

 

[daleyd]

Yeah - direct from inverter would be the jobbie for that.

 

[WorkshopChris]

Depending on the configuration of the original start stop switches some of the older ones are mechanical links to thermal overloads,rather than electrical contacts. This type can still be converted by the use of a couple of microswitches fitted internally to control the inverter digital controls.

 

[Maker]

^^What he said.
Wire the inverter directly to the inverter and modify/replace the original switchgear so you've got the original knob on the surface but with it connected to the inverter's control circuitry (Just had a look at the datasheet for that one and the control circuit is 24v for the switches and 5v for potentiometer).

 

[Wedg1e]

Regarding inverters and contactors... what you CAN do (I have) is take the output from the inverter to the 'input' side of multiple contactors, then arrange to energise the contactors from a switch so that you can route the inverter to several machines, obviously only running one at a time.
Each machine then has its start/stop controls wired via the other contactors so that the buttons only work when the correct switch position (hence contactor) for that machine is selected.
Of course you need contactors with auxiliary contact sets, but it's cheaper than multiple inverters.
I have a 3HP Teco feeding my Boxford and the Perrin mill; one of these days I'll refit the Bridgeport's original 3-ph motor and run that from the same inverter.
Also, if your machine has coolant, the inverter won't mind the small additional load and will happily drive that along with the main motor... but if you use the inverter's speed control function it'll slow the coolant pump as well!

 

[indy4x]

This is very timely as I am in the process of doing the very same conversion on my Fobco 78

Currently the inverter is wired directly to the motor and am using the buttons on the inverter to control the motor.

THe original contactor has been removed and have tested the original stop start buttons on the front of the Fobco and the start button is NO and the stop button NC

Am planning on wiring these to the low voltage control circuit on the inverter so they control the stop start functions

 

[dab4318]

She's arrived! Wrestled it into place. Back hinge was broken so I need to repair it and also sort the wiring situation out.

Let me know how your going to do it Indy. I'll need pics as I'm not that good with electrics.

 

[indy4x]

Nice, like it

And yes they are a hefty lump

Been using mine last few nights and loving it although I did think I'd broken it as it started making some not very nice noises. Turns out it wasn't serious but took another evening to sort out. Still only running direct off the VFD, not had chance to wire up the original switches yet but have been taking photos along the way

The variable speed control is dead useful and initially will only have stop and start buttons at some point would like to add reverse as well

 

[dab4318]

This is very timely as I am in the process of doing the very same conversion on my Fobco 78

Currently the inverter is wired directly to the motor and am using the buttons on the inverter to control the motor.

THe original contactor has been removed and have tested the original stop start buttons on the front of the Fobco and the start button is NO and the stop button NC

Am planning on wiring these to the low voltage control circuit on the inverter so they control the stop start functions

Do you have a diagram of how you are planning on wiring the original switches up to run the inverter? Or is it not as straight forward as that?

 

[daleyd]

Do you have a diagram of how you are planning on wiring the original switches up to run the inverter? Or is it not as straight forward as that?

It should be very straightforward, but it may not be the same for the inverter indy4x has as with yours - you need to get the manual for your model inverter and look in there for the wiring /installation section.

Normally there will be a "common" voltage point which will be provided by the inverter, and all the inputs will be fed from this so it should just be a case of taking the common to one side of your start switch and the start input off the other.

You also need to check how your inverter works, as some require maintained inputs and others only require momentary, while others can be configured for either. Again the manual will be needed.

 

[daleyd]

http://dl.mitsubishielectric.com/dl/fa/document/manual/inv/ib0600366eng/ib0600366engg.pdf

Manual is here^^

See the wiring section (page 14) for how it should be connected, and page 118/119 for an explanation on 2/3 wire control. If your switch is a momentary one (ie push button that releases after being pushed) then you will need 3 wire control with a stop button (Forward/Reverse/Stop). If you want to use a "selector" type switch with maintained contact (ie the switch stays in position when turned) then you use 2 wire control (Forward and Reverse only required). You need to program the inverter to tell it which type you will be using.

There are also different ways you operate the reverse feature, also explained on those pages if you so wish.

 

[Maker]

I've got the same inverter, I'll take a picture of the wiring tomorrow if it would help.