Mentor II DC drive, e-stop deceleration
Mentor II DC drive, e-stop deceleration
(OP)
It was brought to my attention that one of our machines decels significantly faster with the regular stop button than with the E-Stop. I want it the other way around, but I can't seem to control the EStop. There are two Decel parameters but they control the Run Stop and Inch Stop.
From the wiring diagram, I see that the Regular stop button opens the Run Fwd signal only, whereas the EStop opens both Run Fwd AND Start signals. Is there any way to control the EStop Decel when wired this way?
Thank you in advance for any help. This is my first post here, but I'm going to be tweaking and updating several motor control systems in the near future. If I find this site to be helpful I will become a regular user.
From the wiring diagram, I see that the Regular stop button opens the Run Fwd signal only, whereas the EStop opens both Run Fwd AND Start signals. Is there any way to control the EStop Decel when wired this way?
Thank you in advance for any help. This is my first post here, but I'm going to be tweaking and updating several motor control systems in the near future. If I find this site to be helpful I will become a regular user.





RE: Mentor II DC drive, e-stop deceleration
There has been some confusion about E-stop and safe stop and how they are defined for many years. I do not have access to the manual. How is E-stop defined for the drive?
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Mentor II DC drive, e-stop deceleration
What I don't get though, is that there are similar machines with the same drive, and this is the only machine that has this issue. At this point, I'm guessing that the other machines are just facing more resistance and doesn't coast as much. But I am going to dig deeper and would appreciate any more help.
RE: Mentor II DC drive, e-stop deceleration
Why are you bothering with both? Most machines I work on only have one. The big red mushroom. They use the mushroom to stop the machine normally. This has the advantage of testing the stop dozens of times a day. VFD run devices often use the VFD in the e-stop function because it's always the fastest way to stop the motion.
Consider rewiring your e-stop to use the same stopping method as your 'normal' button uses. If there are other machine functions involved in the e-stop not normally operated with the normal stop, then add another contact block to the e-stop to additionally signal those other functions.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Mentor II DC drive, e-stop deceleration
When my boss gets back from vacation I'm going to tell him that I can make the EStop Decel at the same rate as the normal stop, and then disable the drive when it comes to zero speed using a timer (or maybe a zero speed aux contact if i have one). Or we can buy a new drive that has the functions he's requesting. Those are my only options as I see it.
RE: Mentor II DC drive, e-stop deceleration
available solution.BTW I would never include any kind of timer in an e-stop function. It can fail or take too long or....
Keith Cress
kcress - http://www.flaminsystems.com
RE: Mentor II DC drive, e-stop deceleration
You are asking it to be in control, with power removed. Think about that...
You have two options:
- Come up with a way of living with the drive's braked stop capability as the fast "E-stop" and forgo the "drop the power" requirement
- Add a mechanical safety brake to the motor shaft that is immediately released when power is applied, so that if you kill the power with the E-stop, the mechanical brake engages.
What old drives like that one usually offered was an E-Stop option that immediately ignored all Accel / Decel commands and immediately cut power to the motor, often by shorting out the power control device logic circuits (i.e. "base block" on transistors). They would have a set of input terminals that were supposed to be closed, but when opened, as in an E-Stop button, the command line in the logic goes low and the power components are immediately shot with tranquilizer darts powerful enough to stop an elephant.Under "normal" stopping conditions, the drive REQUIRES power, AND it must continue applying power to the motor in order to create the braking effect, in whatever way it does that (there are several).Your timer idea most likely would not stand the scrutiny of any reasonable safety assessment, too much risk of failure. You would be better off just going with option 1 above.
"Will work for (the memory of) salami"
RE: Mentor II DC drive, e-stop deceleration
Mark Empson
Advanced Motor Control Ltd
RE: Mentor II DC drive, e-stop deceleration
But your option 1 and my timer idea would stop the machine in the exact same way. In the event of a failed timer there would be no difference at all. Using an off delay timer would just allow me to disable the drive after a few seconds. It wouldn't bring anymore risk only more protection.
RE: Mentor II DC drive, e-stop deceleration
RE: Mentor II DC drive, e-stop deceleration
Welcome to eng-tips.
Relating to the particular description of 'the machine'. When you say this, do you mean just the mentor dc drive or the whole machine it is connected to? The reason I ask; an emergency stop connected to a machine should relate to the overall integrity of the machine stopping in a common manner, and not being able to restart again individually.
There is a very different definition of stopping and braking when looking at an emergency function. It depends on what the intention is when you hit the estop. If braking is itself a safety requirement,i.e.if the braking does not operate then there is an unacceptable risk of injury,then a fail-safe brake must be provided,such as a mechanical brake with electrical hold off.
Stopping, when it comes to an estop, is generally looking at the inability to restart again.
Introducing timers into a safety system would generally require defined safety relays from my experience.
There are various standards relating to safety and, depending on where you are in the world, should always be checked beforehand.
Finally, when it comes to safety (especially), please understand that the information provided here are tips only from various parts of the world. You have the benefit of being in front of the machine..
Having said that, you have available in this forum, some of the best motor control experts you will find, some have already contributed.
RE: Mentor II DC drive, e-stop deceleration
http://www.kollmorgen.com/en-us/products/drives/se...
I am old fashion and would not want to rely on a timer or software for stopping an E-stop situation, but seems I am old fashion and it is allowed today....
Just had yet another customer decide it met code to NOT disable the drive but instead send software "quick stop" command to drive so it decelled to stop fast, ThEN turn off... For safety. Guess we gotta get with the 90's.... I at least talked them into pulling the 3ph input power at same time as sending the software stop command so once it decelled it had no juice left to malfunction.
RE: Mentor II DC drive, e-stop deceleration
The standard IEC 61800-5-2 defines several categories of "safe stopping functions". Category 0 is immediate removal of power, either bus power, or increasingly, gate drive power (known as "safe torque off"). Without mechanical braking, the motor will coast. (Leads of servo motors can also be shorted together, but this does not help with induction motors.)
A Category 1 stop is a controlled deceleration to a stop, followed by power removal after a fixed time interval. This is the method that the poster wants to use.
A Category 2 stop is a controlled deceleration to a stop, with control maintained at stop, not permitting commands to start up again.
If the reason that the E-stop needs to be invoked is that the drive has lost control, then attempting a controlled stop will not help. That said, I believe I see a trend now that drives can usually tell if they have lost control and shut themselves down, so people increasingly want the quick controlled stop, with a timer relay dropping out power (especially now that most new drives allow you to drop out gate-drive power) after a couple of seconds, which acts (among other things) as a backup in case the drive has truly lost power.