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?...
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?...
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