Power supply/Disconnect vs Leave Connected

[atomarc]

I have a build going in the Benchtop forum. We are into the electrical/electronics phase of this build. The switching power supply is a 48v, 12.5a unit driving a MX3660 combo stepper driver/BOB. This machine also has a 1hp Hitachi drive for the spindle. I would like to leave both of these components powered at all times, unless of course the main disconnect on the cabinet is thrown.

I currently have 3 frequency drives in my shop that remain powered all the time..have been that way for many years.

My question is..can I do the same with the power supply and driver board, leave them powered up all the time? Any horrid downside to this scheme?

Thanks,
Stuart

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[Al_The_Man]

What is the reason for leaving powered permanently?, What not just use the simple E-stop circuit, it can always be re-started with a P.B. when needed.
Al.

[atomarc]

Al,

Maybe I didn't make myself clear. I would like to keep the power supply energized most of the time. This device, being wired to the MX3660 means that it too is powered. It's not running, but it does have power. This whole dilemma is a inrush thing with the drive and the stepper power supply. I would like to keep them both on their own circuit which would always be ON unless the master disconnect on the panel were switched. I know that drives can remain powered for years and years and function perfectly...I'm wondering if the stepper power supply and 'not-running' but connected driver can hang out in a powered state with no ill effects.

Stuart

[Al_The_Man]

Should be no reason why not.
Al.

[ger21]

I'm wondering if the stepper power supply and 'not-running' but connected driver can hang out in a powered state with no ill effects.

If the power supply is powered, and it's connected to the drive, than the drive IS running.

[atomarc]

I may be flogging a dead horse here but I have always felt that a device could have power..be powered, but not be ON..not be running. I have three drives in my shop that are always powered, but they are only running when I hit the GO button. The stove in the kitchen is always plugged in and powered but it's not ON until mama turns the element ON.

I will assume that the stepper driver, being solid state, will just sit there in a powered condition, biding its time until MACH-4 tells it to do something, and really won't know the difference.

Stuart

[ger21]

When a stepper drive is powered on, it is providing power to the motors, holding them in position.
If you're drives can use an enable signal, you can use that to disable them when your control software is not running.
But if they are not disabled, they are indeed powering the motors, even with the control software not running.

[Al_The_Man]

I agree, if not using an e-stop then use the disable, the down side with steppers is they can be turned by accident or some means, so that the position is lost when none powered.
System that use servo's and the encoder is taken back to the central motion controller such as a in-slot control card, you can move the axis where ever you wish manually or if back driven etc when off, and they retain/record the position throughout.
Al.

[atomarc]

So...this thread is showing exactly how much I have yet to learn about this stuff. Here is what I think I'm seeing. The power supply is powered up and connected to the driver board. The driver has not been 'enabled' by Mach-4 so it is not powering the motors, they are free to move. Is that correct? The stepper driver has power to it but it's not 'enabled'..it's not doing anything, just sitting there waiting for a command to do something. It's turned OFF, so to speak. Is this right? As an aside...this site is excruciatingly slow to access and load, at least for me. Takes probably a minute to load and make a post. It used to be super fast, wonder what's going on? Stuart

[steve323]

As soon as power is applied to a stepper motor controller, it will provide power to the motors. They will be locked to their current positions and won't be able to move until you power up the PC and start Mach4. Some controllers revert to a slightly lower power state after a period of inactivity. The motors will still be consuming some fraction of their active power.

Steve

[Al_The_Man]

If the drives are powered and enabled then they are active, two methods to disable is remove drive power OR use the enable input logic to disable, either way, they are then able to be turned by whatever external means.
In Mach system, there is no feedback to the control that the drives have been moved in this condition.
Al.