Stupid question Alert For SMC Flex Soft Starter.

I’m not a regular user of soft starts but the SMC Flex list the aux contacts can be set to “Normal”, what does normal mean? The manual doesn't say from what I could find.

Okay and another, you can set it for fault or alarm…isn’t a fault an alarm? What's the difference?

Thanks,
Bob O.

You will find the explanation in Appendix B of the user manual for the Aux parameter. Per that table Normal = SMC in Run, so it is saying it has a valid run command applied and it is not otherwise faulted. I tend to use up to speed as that is the information I really need.

In the world of VFDs and Soft Starters (at least Allen Bradley, but most seem to be the same) a fault is a problem that will not allow the device to run and/or shuts it down. An alarm is more like a warning, to alert you to a problem that doesn't need shut the device down but to tell you a problem exists that may cause issues.

Think of these like a traffic light. Normal = Green (go to go, run), Alarm = Yellow (caution), Fault = Red (Stop)

Stupid question? OR Ab"normal" descriptor choice?...

*EDIT - Written before Mark replied. So apologies for any repetition...

Hi Bob,

Bob O said:

...the SMC Flex list the aux contacts can be set to “Normal”, what does normal mean?...

Click to expand...

28948 - SMC-Flex (150-F) - Normally Open N O
Access Level: Everyone

"Normal" just means the drive is running. The aux contact will be normally open (NO) when the drive is stopped and the aux contact will close when the drive is running, indicating the drive is enabled and the motor is rotating under the control of the drive.

Bob O said:

...you can set it for fault or alarm…isn’t a fault an alarm? What's the difference?...

Click to expand...

Another confusing one, or two?...

44168 - SMC Flex Softstarter: Providing Alarm or Fault Indication
Access Level: Everyone

They still don't explain any differences between the two there either, do they?

Maybe this will help...

Setting any of the aux contacts to "Fault" N/O or N/C means that the contact will switch for any of the fault conditions listed in the SMC-Flex User Manual (Diagnostics: Fault Codes Page 8-3).

Fault conditions will usually always stop the drive.

Setting any of the aux contacts to "Alarm" N/O or N/C, means that the contact will switch for any of the alarm conditions listed in the SMC-Flex User Manual (Appendix A: Specifications - Alarm Contacts).

Alarm conditions will usually not stop the drive.

Alarm conditions are more pre-warnings that a fault is imminent. Certain pre-fault conditions can be detected by programming an alarm indication level for some of the fault conditions. The alarm indication level is set lower than the fault indication level. This is useful for early warning detection and can be used for automatic and preemptive shutdown before the fault is triggered. Some of the fault conditions include both an Alarm Level and Alarm Delay setting. Once an Alarm Level is reached the Alarm Delay must expire before the Alarm aux contact will switch.

For more information on the Alarm conditions and their configuration, see these references which are also in the same User Manual...

Product Overview: Protection and Diagnostics Page 1-11

Programming: Motor Protection Page 4-15

Appendix B - Parameter Information: Page B6 -
(Note: A = Alarm; Lvl = Level; Dly = Delay)

P50: Overload - Overload A Lvl

P53: Underload - Underload A Lvl
P54: Underload - Underload A Dly

P57: Undervoltage - Undervolt A Lvl
P58: Undervoltage - Undervolt A Dly

P61: Overvoltage - Overvolt A Lvl
P62: Overvoltage - Overvolt A Dly

P65: Unbalance - Unbalance A Lvl
P66: Unbalance Unbalance A Dly

P69: Jam - Jam A Lvl
P70: Jam - Jam A Dly

P76: Ground Fault - Gnd Flt A Enable
P77: Ground Fault - Gnd Flt A Lvl
P78: Ground Fault - Gnd Flt A Dly

Also, as a by-the-way, take note in this PDF link of the difference in the default settings for aux contacts between firmware revisions 3.xxx. & 4.xxx...

800662 - MV SMC-Flex Aux Contacts in Firmware 3.xxx and 4.xxx

The choice of "Normal", as a status descriptor, is always one that creates fierce ambiguity, in my opinion. It is just too vague and open to interpretation. For a drive, or the like, a status of "Running" or "Running" and "At Reference" is the clearest way to describe the expected status of the drive when at a minimum it has been asserted both a start enable command and a valid speed reference.

Alarmingly Faulty terminology...

"Fault" and "Alarm", when used interchangeably, are another two that can cause untold confusion. At their most simplest level, the clearest description I would use for these two is...

For the same Fault condition:

The Fault condition is signification of the Fault itself being currently present.
The Fault condition, by itself, does not constitute an Alarm condition.
The Alarm condition is optional.

The Alarm condition is the signification, or annunciation, of the presence of the Fault condition, or that the fault condition is imminent.

The Fault condition is the status you want to be informed of.
The Alarm condition is the method used to inform you of said status, or potential for said status.

They should not be used, or confused, as being interchangeable.

Regards,
George

"Normal" is used because it does NOT in fact ONLY mean that the motor is actually running, it means that the soft starter is functioning properly, AND connected properly AND has been commanded to run. I capitalized the ANDs because they must all be true for the "Normal" indication. Unlike an electro-mechanical device, the SMC will not allow you to attempt to start if the line conditions are not correct, or if one of the load conductors is disconnected, or if there is a shorted SCR (think welded contact). Those are conditions that would also give you a fault indication, but because you CAN change some of them to be Alarm and not Fault or even disabled them (i.e. Under Voltage), that creates a possibility of attempting to start and it doesn't, but you will not know it. So using "Normal" means "the SMC is energized, properly connected, in good working order and successfully operating the motor", but that doesn't fit on a nameplate very well.

In addition, "Running" is not actually indicative of the motor being fully capable of being used, because in a lot of cases it must be done ramping. I have used soft starters that utilized "Running" as the aux contact definition and have seen it misused and cause problems. For example a large compressor mfr made that mistake and used the "Run" aux in a scheme to detect no-flow by initiating a timer that jumped around a flow switch contact. But occasionally they would get nuisance no-flow trips, because the ramp time was variable based on conditions, so sometimes the motor was not at full output when the timer expired. I simply changed the feedback to initiate the timer to be "At-Speed".

"Normal"ly I would not mind...

Yes, as I said, it certainly is open to interpretation my friend. I cannot disagree with you and I suppose here in lies the problem. We can make "Normal" mean whatever we want it to. Or more, they, the manufacturers can. If I did not already know what it meant for this particular device, until you explained it to me so eloquently, then I would have struggled to derive its intended meaning just on the face of reading the word "Normal". At a glance, I could interpret it as meaning the drive is stop asserted, no general fault or system fault, ready to enable. It would not, at a glance, suggest to me that anything is active or running.

But, if "Normal" can mean those conditions have been met, then why cannot "Running" mean the same? "Running" as in "Running Healthy". "Running" as in "I cannot get to this status unless "...they must all be true for the "Running" indication...". We are, after all, only talking about terms here at days end.

As I said, I am not disagreeing with you on what it does mean here. We are just discussing the choice of descriptor used. I'm forever interpreting what is meant by certain terms or phrases within this industry and I usually, like you are doing here, read it as is, and relay it to others as is; trying to explain its meaning as best I can, even if somewhat ambiguous.

But in this case, it does not quite sit right with me. I still believe, in the industrial controls industry, "Normal" is too ambiguous a descriptor for an "At Run" or "Running" or "Running at Reference" status. I can live with it. It just would not be my preference for such a status, that's all.

Speaking of status'...

The "Running" or "Running at Reference" status that I was talking about being preferential was more related to fixed speed reference drive applications. The drive is start asserted and a fixed speed reference is commanded. The speed reference does not tend to change or is not dynamically changing according to a process. When the drive detects that it is synchronized with the motor, and that the speed reference has been achieved, then these conditions can be used to indicate a "Running" and or "Running at Reference" status.

If we introduce ramping or modulation into a drive application, then we introduce a higher level of condition monitoring. We now need to constantly check that the commanded speed, or rate of change of speed (Accel, Decel) is being achieved. But we are now more into loop control. A higher order of control and feedback is usually present and we are now gone away from the simpler requirements of is it simply "Running" and or is it "Running at Reference", or "Normal", for that matter.

But let's not muddle soft starters with VFDs, too much.

We actually have some SMC-Flex soft starters "Normal" here for years. Very reliable little work horses.

Regards,
George

Rockwell's KB articles muddy it themselves by referring to the SMCs as "drives" in more than one instance. I wish they wouldn't do that...

Sorry for the delayed reply.


Started the very simple system early Friday morning using the “Up To Speed” and “Faulted” selections for the aux contacts and now I have more reading to do on this based on the KB links provided.
I thought I searched the KB but couldn't find what I was looking for must have been my choice of works.


Thanks group,
Bob O.

Fault conditions will usually always stop the drive.

Click to expand...

Speaking of ambiguities...

I would define "usually" as the majority of the time and "always' as every time, but is "usually always" "always except for when it doesn't" or "never except for when it does"?

Often, I am usually always never wrong...

Steve Bailey said:

...is "usually always" "always except for when it doesn't" or "never except for when it does"?

Click to expand...

Well that is an age old one Steve, but touche. A grammatical faux pas on my behalf, but I am human, despite the rumours!

What I simply meant to "say" there was that Fault conditions will usually, or most always be designed to stop their related device. This was in part explaining the difference between a Fault and an Alarm, while explaining the functions of the aux contact options.

But I know that you know what I meant and you're just yankin' my chain.

I think that we tend to subconsciously use such contradictory phrases when we're attempting to convey a more general meaning where something is typically one way, but not definitively. The "always" was completely unecessary here, of course, and no intended meaning is lost by removing it...

"Fault conditions will usually stop the drive."

However...

It could also be that I didn't read through all the possible Faults for this device and so I couldn't be sure if all Fault conditions do stop the device, so I subconsciously covered my tracks by trying to cover all eventualities. But, I'd never openly admit that, now would I?...

The above could have drawn the question from some astute reader, such as yourself...

"Ok, so when won't a Fault condition stop the drive?"

Then I would have to go read through all the Faults and would then have to reply..."Never". Why? Because I've just read through all the Faults and they do all stop the drive. See what you've made me have to do?...

So...

Fault conditions will always stop the drive (soft starter).

Having to be careful not to make unqualified statements is a hazard of the "job" here on the Forum. Ask Ken. He often says "In general...". He started using that disclaimer some time back. He won't admit it, but I know he uses it in fear of the ever watchful "G-Police"...

Ken Roach said:

Blanket statements and categorical recommendations are fine.... until George shows up !

Click to expand...

Making grammatical faux pas and hoping to get away with them are fine... until Steve shows up !

Regards,
George.

G.