Pump alternator for DIN rail mounting. It has two inputs from clean contact (pressure switch, float, etc.) and two triac outputs. One input (P1) alternates the outputs, meaning each time it is activated, it switches to the other pump from the previous time. The other input (P2) activates both outputs with a small delay (4 seconds) between them. P2 is set to activate when there is a higher demand that cannot be met by one pump alone.