PURPOSE: To perform stepping to a normal machine automatically so as to supply water without complete failure of a system when any of control base boards causes a failure by providing the control base board for each inverter which controls each pump head.
CONSTITUTION: Control base boards 16, 17 on which microcomputers 13, 14 are mounted respectively are provided independently for each of inverters 19, 20 which control speed of motors 21, 22. A display base board 18 on which a microcomputer 15 is mounted is also independent from the control base boards 16, 17. The control base boards 16, 17 output corresponding frequency commands 16 (a), 17 (a) to the inverters 19, 20 after operating and processing pressure signals 10 (a), 10 (b) from a pressure sensor 10. After that, the inverters 19, 20 send back reach signals 19 (a), 20 (a) which inform that frequencies have reached the frequency commands 16 (a), 17 (a) outputted from the base boards 16, 17 to the base boards 16, 17.
TANABE MASATOSHI
ITOU KOUICHI
KAWAMATA MITSUHISA
