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Im trying to set up this drive to clear faults automatically by using terminal 15, changing the parameter to clear fault. i have installed a 120 volt cube relay and a time delay relay. The operation works but as soon as the drive faults, the timer comes on asap and clears fault. and the timer stays on 24-7. is there any other way to wire up this timer to actually work the way its suppose to, time on delay and time off delay. Any ideas will be helpful. Thanks.
 

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Im trying to set up this drive to clear faults automatically by using terminal 15, changing the parameter to clear fault. i have installed a 120 volt cube relay and a time delay relay. The operation works but as soon as the drive faults, the timer comes on asap and clears fault. and the timer stays on 24-7. is there any other way to wire up this timer to actually work the way its suppose to, time on delay and time off delay. Any ideas will be helpful. Thanks.
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Don't know what you have done as the timer, but it sounds like maybe you have used an On-Off delay timer? An On-Off delay timer means that you initiate it with a command signal, and it waits before changing state as an On Delay timer, but then stays that way until you REMOVE the command signal, then it continues to STAY in that state until the Off time expires, like an Off Delay timer would. If you don't have anything removing the command signal, it never resets.

So on the SMC Flex, when you set it up for Option #2 Input to be "Clear Fault", changing from low to high on that bit initiates the fault clearing. But assuming you are using 2-wire control (meaning a maintained On-Off command, not a 3-wire Start-Stop momentary push button), if you are using the fault RELAY of the starter to initiate the timer and wanting the timer contact to clear the fault, here's the problem. When your fault happens and the fault relay is initiated, it times out the timer which changes state to Input 2, which does give the SMC the command to clear the fault. But it CANNOT clear the fault RELAY state yet if you have not REMOVED THE RUN COMMAND. So the fault relay stays in a tripped state, keeping the timer from doing it's thing on the Off-Delay side of it and nothing changes.

The SMC Flex will also clear faults* automatically by cycling the Run command. So you didn't really need to wire the timer to Option Input #2 to do this, all you need to do is put a NC contact of your On-Off Delay timer in the Run command line. When a fault happens, it initiates the timer and after the delay, the timer changes state and OPENS the Run command line. The starter will have already stopped because of the fault, but this will CLEAR the fault and allow the starter to run again after the Off Delay timer times out. And DO NOT use a plain On Delay timer for this. It will work, but it will IMMEDIATELY reset a fault, and if the condition that caused it is still there, it will repeat to destruction. use the On-Off delay timer and give it some time between resets, maybe 10-40 minutes for the motor to cool down.

By the way, for that EXACT reason, it's not a great idea to do this. What are the faults you are getting that need to be reset? Can you fix that problem?

* You cannot clear all types of faults. Shorted SCR cannot be reset, Open Gate can only be reset 3 times, and Motor Overload can only be reset after the thermal motor model has determined that the motor has regained sufficient thermal capacity to re-start successfully, which it learns over time.
 
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Discussion Starter #4
Thank you JRaef for all the information, very helpful. Well the reasoning for a timer, this is a very important sewage pump station and we had an issue over one weekend where power keep on going in and out and it faulted out the drives. LINE POWER LOSS A,B,&C phase, and the wet well almost overflowed into a major water supply. so my supervisor asked if there was anything i could do to reset the drive quickly and start back up. Other faults really havent had an issue with yet, knock on wood.
 

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So what is controlling the On-Off of these starters? Is it just float switches? If so, that explains why the Run command doesn't open when the power comes back on. If there is a PLC however, just add some code to open, then reclose the Run command, that will clear the faults.

You could also accomplish this by just putting a Phase Failure Relay on the control panel that has a time delay on the fault contacts, then wire those contacts in series with the Run command. So after a power failure, the contacts open, then when power comes back on, they stay open for a few seconds, allowing the fault on the SMC to clear. When the delay on the Phase Failure relay times out, the contacts close again and if the float switch is still demanding the pump, it starts.
 
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