jguidotti
Member
Hello everyone, 1st time user (from Oz). I am currently writing logic to control 3 potable water distribution pumps with 1 pressure transducer(0-1000kPa)in the line. Having the pumps turn on/off at certain pressures is the easy bit. But I am having issues trying to set up Duty/Standby situation, eg if the pump requested to run fails how do I get the next pump to start(as at the moment it wont start until the pressure drops). To try and make this easier below I have listed what the On/Off set points are and what I wont to achieve.
<700 pump 1 latches
>750 pump 1 unlatches
<650 pump 2 latches
>700 pump 2 unlatches
<600 pump 3 latches
>650 pump 3 unlatches
1. Pumps can start in manual if motor starter ok (no problems)
2. 1 pump to run, demand changes, pumps 2 and 3 start and stop to keep line pressure stable - approx 700kPa. (no problems)
3. If 1 pump is running due to demand and fails (or is being asked for a start and fails) the next pump starts and so on.
If anyone has any thoughts or ladder examples that would be much appreciated.
Cheers
Ozzie Lad
<700 pump 1 latches
>750 pump 1 unlatches
<650 pump 2 latches
>700 pump 2 unlatches
<600 pump 3 latches
>650 pump 3 unlatches
1. Pumps can start in manual if motor starter ok (no problems)
2. 1 pump to run, demand changes, pumps 2 and 3 start and stop to keep line pressure stable - approx 700kPa. (no problems)
3. If 1 pump is running due to demand and fails (or is being asked for a start and fails) the next pump starts and so on.
If anyone has any thoughts or ladder examples that would be much appreciated.
Cheers
Ozzie Lad