Parameter for Drive Restart on Power Restored?

[plcgrasshopper]

Hello all,

I am currently trying to program a PowerFlex 525, version 7.0. We had a power outage recently and when the power was restored, the agitator drives did not restart.
However, some mixer drives did restart when power was restored.

The only parameter I can see that is connected to that is A541, but in the drives that successfully restarted, that parameter is a 0.

Any idea on what parameters are associated with this function?

Any help would be greatly appreciated!

Thank you!

 

[joseph_e2]

I'd have to dig into that one, but I'm not sure auto restart tries is what you need. That one seems to affect the drive automatically resetting faults and restarting.
Look at t064 and see if it's set to "Level Sense" instead of edge trigger or momentary.

 

[plcgrasshopper]

I'd have to dig into that one, but I'm not sure auto restart tries is what you need. That one seems to affect the drive automatically resetting faults and restarting.
Look at t064 and see if it's set to "Level Sense" instead of edge trigger or momentary.

Is a power loss not recorded as a fault since it power cycles the drive? Hence clearing all faults?

 

[glenncovington]

Be careful. NFPA 79 states Machinery/Processes should not restart automatically after a power cycle if there is a potential hazardous condition. It should require operator intervention to verify starting is safe.

 

[chelton]

Check parameter A543 - Start at powerup. If on cycling the run signal is not required.

 

[plcgrasshopper]

Be careful. NFPA 79 states Machinery/Processes should not restart automatically after a power cycle if there is a potential hazardous condition. It should require operator intervention to verify starting is safe.

Would you consider a completely enclosed agitator as a hazardous condition?

 

[Mitch.]

Would you consider a completely enclosed agitator as a hazardous condition?

Yes. Where the drive has power removed during LOTO to enter the area, for whatever reason the LOTO failed then power was restored the drive will start. That's a hazardous condition.

Instead, you can check if the enclosed agitator has been locked and closed with some kind of hatch interlock or safety switch with an acknowledgment button to deem the area clear first before sending a start signal to the drive.

 

[plcgrasshopper]

Yes. Where the drive has power removed during LOTO to enter the area, for whatever reason the LOTO failed then power was restored the drive will start. That's a hazardous condition.

Instead, you can check if the enclosed agitator has been locked and closed with some kind of hatch interlock or safety switch with an acknowledgment button to deem the area clear first before sending a start signal to the drive.

Ahh, fair point. I may see if there isn't a prox switch on the tank and add that into the interlock rung.

 

[robertmee]

Ahh, fair point. I may see if there isn't a prox switch on the tank and add that into the interlock rung.

If there is the possibility of injury, a prox to a standard input and used in logic with your agitator start, doesn't really meet any safety category. You would need a safety PLC, safety input for the prox, and safety outputs to the STO inputs of the powerflex. Alternatively, you could use a prox(s) into a safety relay and that relay hardwired into the STO of the 525. The highest safety would be achieved with a locking hatch where you proved no motion before releasing.

 

[joseph_e2]

I'm a fan of the locking door with standstill verification. Several ways to achieve that.

I also agree about prox sensors. I haven't looked in a while, but when I did Turck was the only manufacturer who made a safety-rated prox sensor with dual OSSD outputs. You would still need to make sure the sensor is protected and "unlikely" to fail or be bypassed since they can easily be disabled with a magnet. They're definitely not my preferred option but we've had a few situations where nothing else would do. In this case, a locking interlock switch with lock monitoring and standstill verification is how I would probably proceed.

 

[plcgrasshopper]

Just wanted to give you all an update. It was a latching first scan bit that would drop out the Run Command and hold it HIGH on a cycle of five seconds until the drives are up to the commanded speed or they reach the certain amount of allowed attempts.