Wiring - What gauge for PS vs Limits vs Other

[AJ_Mac2001]

Hi folks,

I've found a few posts on wiring but hope to learn and summarize it in one... a) to aid in my upcoming wiring job, and b) so future searchers hopefully find what they're looking for in one thread. BTW... I am electronically ignorant so please "dumb down" any suggestions

Ok, so my longest run will be ~25ft (to get to my Z axis). I'm using servo motors (1100oz/in) and want to wire up to serve my Gecko 320's... so I guess that means the wire should be capable of 20Amps/80Volts peak.... but likely never see that and therefore could be a lot less (I'm cautious and have no problem with overbuilding) I'm putting limits on both sides of my X axis to square the gantry with Mach2, and of course on Y and Z. My motor/encoder cables are being supplied from Axxus, but for what its worth to make this info complete... please suggest so that others may use this as a resource. So now for my list of questions.

1) What gauge wire do I need to use for my limits/home circuits?
2) Can Cat5 cable be used for limits/homes? i think its 24 Ga.
3) What Ga wire should be used to wire from the PS to the Gecko's and other "stuff" in the control box?
4) What Ga wire should be used to wire from the Gecko's to the Servo's?
5) What's the deal with shielding? Is this just for encoders? Any cheap ways to accomplish this?
6) Inline fuses... can I get away with one coming off the Powersupply, or should I fuse each gecko individually? Anywhere else I need to consider?
7) [and finally] My estop... Mach2 has the input for an estop (on 5V I assume) Does this mean I need two Estops... one for a software Estop, and one to kill the main power??


OK, that turned out longer than I expected... sorry! I'm accumulating the electronics and hope to make a run of it in about a week when my PS arrives and other electrical goodies. So far its just 4 Gecko 320's sitting on my desk!!

Thanks as always.

[abasir]

For wire gauge details, go here http://www.powerstream.com/Wire_Size.htm

[AJ_Mac2001]

Anybody else out there used Cat5 cable??

[fyffe555]

AJ_mac2001

I used shielded cat5 for step/direction/enable and limit switches from my LPT breakout board to drivers and machine. In otherwords just the signal, non-power stuff. Note also that its not the usual cat5 or cat5 riser spec but the shielded stuff used for high density patch panels. Technically one end of the shiled should be grounded but I haven't need to. It all runs well over about 12 feet.

Cat5 should be 24awg solid. There's a number of Power over ethernet (PoE) projects that supply up to 48v and 40watts DC along side signal. However cat5 has around 3ohms per 100 feet so over any significant distance you'll get a voltage drop and the the loss is put out as heat. The same goes for all wire of course, but what I'm suggest is that cat5 is fine for runs for signal stuff and low voltage/power say up to 48v/40w but not for motor power, get the 'big' 10/12/14/16 awg for that and look to see what the drivers (Gecko's etc) have sized for thier wiring connections.

hth

[balsaman]

Use min. 16 guage for the geckos and motors, 14 or 12 guage is better.

Encoder and limit cables should be shielded. You can get shielded cable, so that's the best way to go.

Get a Estop with 2 sets of contacts, one to kill power, one to tell Mach 2. Actually your limit switches can also be in series with this contact.

Not sure about fusing. I used one fuse for everything on the DC side of the PS (mind you it's ony a 3 amp fuse...never blown it yet). NEVER fuse between the gecko and the motor unless you want to replace the drive with the fuse.

I don't like CAT5 cable for limits or encoders because it's solid wire. Stranded is more flexible and meant for this type of application. Cat 5 is meant for running thru walls and other non motion applications. That said, it has been done....and it's readily available.

Eric

[AJ_Mac2001]

Thanks Balsaman,fyffe555 and abasir

I'm dying to get this machine to life... all the fun parts are in the mail so I''m taking the time to disassemble and paint the whole shabang because I know I'll never get to that once she's moving.

Imagine there are a few unknowns between its present state and powered motion, but can't wait to start a new thread called "my first part"!


Later,
AJ

[DaSigntist]

I used from Radio Shack 24 gauge 278-757 $5.99
Rainbow wire. 4-conductor, 24-gauge solid wire. 7m (25 ').

Works perfect no heat....

Hang in there AJ won't be long keep me updated!

[ballendo]

Originally posted by balsaman I don't like CAT5 cable for limits or encoders because it's solid wire. Stranded is more flexible and meant for this type of application. Cat 5 is meant for running thru walls and other non motion applications. That said, it has been done....and it's readily available. Eric [/B]

Another thing to consider is that if your wiring breaks while the drive is energised, you're quite likely to burn up the output transistors of your drive, or worse...

The advice to use stranded wire ,and of a sufficient guage, is good advice, IMO...

Ballendo

[AJ_Mac2001]

Thanks again folks for all the advice/support.

[sol]

Just a "for what it is worth"....

A 12 ga. extension cord is an excellent value for the servo cables; a 50 ft. cord with the molded-on plug and receptacle is quite a bit cheaper than the equivalent 12-2 w/g stranded cable sans connectors (cut from spool, retail)...go figure.
When cutting off the plug leave enough wire on it so that it can be used as the power-supply's power cord.

I used 14 ga. for all high voltage internal box wiring, it is sooo much easier to use than 12 ga. and plenty big enough for those short runs. For the low voltage wires, strands from Cat5 or phone wire are fine.

Marriss the Gecko deity told me the following...and I have done as directed.
The Geckos require +5 Vdc from the computer; this can be taken directly off of the computer's power supply or the game port. Use a ½ Amp fuse in this wire, especially if coming off of the power supply; that is a relatively high current wire that would let out a lot of smoke were it shorted. Put the fuse as close as possible to the computer's power supply, not the Geckos.

Good Luck!

[AJ_Mac2001]

Thanks for the tips!