Pump Automation/Squencing
Pump Automation/Squencing
(OP)
So I am working on a project but am not sure about one aspect. I am working on a system that has 2 pumps, 1 main, and 1 stand-by. Each time the pump is to turn on it will alternate which pump turns on, not a issue becasue I can just use an alternating relay. The trouble I am having is that if say Pump 1 is to turn on but does not it then needs to turn pump 2 on and alarm that pump 1 has failed. I was thinking I would install a flow switch on each pump discharge between the pump and check valve. I figured that i could use some delay relay of sorts and so when the pump turns on the flow switch has X amount of time to sense the flow and if it doesn't, then it would alarm and turn on the other pump. My question is, is this the best way to do this or is there a better way then using the flow switch and so forth? Thanks for your input and help in advance.





RE: Pump Automation/Squencing
IMO, a pressure switch will be better option as it does not get into the flow path.
Pump or motor failed to start alarm can also be incorporated into the motor switchboard.
RE: Pump Automation/Squencing
As far as the flow switch I was figuring of using something similar to this: http://www.flowline.com/thermoflo_xt10.php
I thought about a pressure switch but if the pressure in the line remains relatively constant then I figured the pressure switch wouldn't work. I also guess I should explain the system a little more.
The pumps are pumping reclaimed condensate back into the system. The pumps only turn on once there is a given level in the tank.
I feel as though a pressure switch has a big contraint, it needs a drop in pressure from the intial/system pressure to be effective. This is why I figured a flow switch would be best. Maybe I am wrong, I am human and do screw up at times.
All the logic is controlled by a PLC/Smart Relay.
RE: Pump Automation/Squencing
After all, the level in the sump is what matters, the pump(s) should lower the level, failure to lower, or rising level indicates a fault.
At times I have used a separate high level detector that will alarm even if the primary level sensors fail.
Steve
RE: Pump Automation/Squencing
What is your system pressure with and without pump running?
Not sure what type of condensate (steam?) you are pumping.The flow switch you proposed did has a note that said{b]The flow sensor is best applied in applications with relatively constant temperature[/b].
Pressure sensing or flow sensing both required additional instruments and wiring between pumps and MCC.
If there is continuous of condensate inflow to sump, then level control / detection is a sure way of pump failed to start or failure
detection.
Another method is by sensing the motor current. If the motor did not start, there is no current detected. This method can be carried out within the MCC without external wiring.
Suggest you talk to your I & E department to work out the most suitable method.
RE: Pump Automation/Squencing
I had cpmletely forgot about pump failure by measuring current. This seems to be the easiest way and best way.
Thanks to everyones input.
RE: Pump Automation/Squencing
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: Pump Automation/Squencing
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If we learn from our mistakes I'm getting a great education!
RE: Pump Automation/Squencing
I Thought you have been in the pump line long enough to understand that when ever a pump failed to turn or push out water, it is the pump problem.Never mind if the motor is not there or the the wires were not connected.
ScottyUK,
Would appreciate if you could elaborate your above statement.
Thanks.
RE: Pump Automation/Squencing
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus