Slip Ring

Hello world,

I have a 5A slip ring, can I pass enough current through it for four 2A steppers running at 60%? (4*(2*.6)=4.8A?)

How do you establish the 60% figure

ON for 60% the OFF for 40% each time period (whatever that might be) from a fixed current source

or

60% of a 2A analogue supply, ie 1.2A continuous

It's my understanding that servos are "digital" devices in that they are fed a stream of current pulses

If that's the case then your 'rings' will be carrying 8A per phase

You can "overload" systems provided you are willing to accept reduced (sometimes greatly) life-span

jackrae:
How do you establish the 60% figure

ON for 60% the OFF for 40% each time period (whatever that might be) from a fixed current source

or

60% of a 2A analogue supply, ie 1.2A continuous

It's my understanding that servos are "digital" devices in that they are fed a stream of current pulses

If that's the case then your 'rings' will be carrying 8A per phase

You can "overload" systems provided you are willing to accept reduced (sometimes greatly) life-span

I'm sorry, I wasn't speaking PWM, I meant like your second example at continuous run I'm estimating (well my partner is estimating) they'll run about 60% current draw.

And just to clarify, I did say stepper not servo.

This is for the power supply isn't it? You would be well advised not to use any non-solid connection
between a motor driver and a motor, due to the inductance.

The question you ask isn't very meaningful without the supply voltage quoted, since the supply current
depends on the supply voltage (and the maximum speed / load on the motors too).

Do you have the right kind of driver? Explain more about your setup please, ie confirm if this is power only.

55thSwiss:
And just to clarify, I did say stepper not servo.

Point made (there s a difference) but I was referring to your stepper motor question.

Probably. If it gets hot and starts smoking then you need a bigger/better one. Is this something that has to work for a long time in the hands of idiots or is it just a science fair project?

MorganS:
Probably. If it gets hot and starts smoking then you need a bigger/better one. Is this something that has to work for a long time in the hands of idiots or is it just a science fair project?

BA senior class project, doesn’t need to function forever.

MarkT:
This is for the power supply isn’t it? You would be well advised not to use any non-solid connection
between a motor driver and a motor, due to the inductance.

The question you ask isn’t very meaningful without the supply voltage quoted, since the supply current
depends on the supply voltage (and the maximum speed / load on the motors too).

Do you have the right kind of driver? Explain more about your setup please, ie confirm if this is power only.

Sorry for the lack of info, I understand it’s tough without all the information.

I’m going to grab a parts list soon to better describe the scenario.

If you're doing a BA in some form of engineering, why are you asking a "hobby" site for technical advice. You should be teaching us :slight_smile:

Perhaps not - loads of posters here have many higher degrees and lots of experience....

As to the question - yes ok - but the slipring is not a perfect connection, and may introduce significant
noise and some voltage drop , and if it momentarily interrupts a current flowing into inductive loads, significant voltage transients.

To help further a detailed circuit diagram would be helpful...

Allan

MarkT:
This is for the power supply isn't it? You would be well advised not to use any non-solid connection
between a motor driver and a motor, due to the inductance.

The question you ask isn't very meaningful without the supply voltage quoted, since the supply current
depends on the supply voltage (and the maximum speed / load on the motors too).

Do you have the right kind of driver? Explain more about your setup please, ie confirm if this is power only.

Here's the actual parts list we were planning on using:

4xStepper Motors McMaster-Carr

4x Driver McMaster-Carr

Slip Ring http://www.slipring.com/series-through-hole-slip-rings-1800-p-410-l-en.html

Power Supply https://www.amazon.com/BMOUO-Universal-Regulated-Switching-Computer/dp/B01EWG6YT8/ref=sr_1_16?ie=UTF8&qid=1489787746&sr=8-16&keywords=switching+power+supplies

Hi,
The link to the slip rings is to a 18channel at 5A each, so a motor per pair of channels will be okay.
Unless you only have 2 available for motor supply.

BUT:

The channels are rated as signal, this is because the slip ring material is silver plated to keep noise down, using them to supply an inductive load like motors may be destructive to the coating and arc up from the brushes.
I have serviced slip rings and arcing brushes spread conductive dust over ALL the slip ring tracks.

You may be batter off looking up a slip ring with a combination of power and signal, if some have to be signal rated.

Tom.. :slight_smile:

TomGeorge:
Hi,
The link to the slip rings is to a 18channel at 5A each, so a motor per pair of channels will be okay.
Unless you only have 2 available for motor supply.

BUT:

The channels are rated as signal, this is because the slip ring material is silver plated to keep noise down, using them to supply an inductive load like motors may be destructive to the coating and arc up from the brushes.
I have serviced slip rings and arcing brushes spread conductive dust over ALL the slip ring tracks.

You may be batter off looking up a slip ring with a combination of power and signal, if some have to be signal rated.

Tom.. :slight_smile:

Thanks for the info Tom, I was unaware of exactly how the channels work and how to divide it up.