Duty rotation for pumps

I have to make a ladder logic for a pumping station for 4 pumps, 3 duty and 1 standby, How can I change the duty of a pump if it is running for a long time?

three pumps are interlocked to level measurement from a level transmitter, if 20% level than 1st pump starts, if 45% level then 2nd pump will start and if level of tank is 75% than 3rd pump will start and for level is 90% ,4th pump will also start...
But if for a long time level is 25-40% than only pump 1 will have to run continuously, that could increase its worn...I want to change duty in such case.

experts kindly help,
It will be a great favour from your side.
Thanks in advance

Search the forum. You'll find all you need to implement this.

As mentioned, it's been covered before. .. Again this week actually.

I see this concept of even wear coming up often, but I sometimes wonder why people want to do it. Do you really want all your pumps to be worn the same amount? So when one falls over, the other 3 are not far behind...

Personally I prefer a 75% / 25% duty ratio. Wear one machine out at a time.

But if you really want to swap duties if a pump is running for a long time, then just time / count the minutes it's been running for. When it has run for more than your time Setpoint, then do a duty change.easy.